The study, conducted at a single center between May 2008 and February 2020, followed 48 consecutive patients who were treated for a total of 53 biopsy-confirmed papillary renal cell carcinoma tumors. These were not healthy surgical candidates: the patients had been deemed unfit for partial nephrectomy, the current gold-standard operation for localized kidney cancer, because of advanced age, impaired kidney function, or poor overall condition, while some had simply declined surgery. Every case was reviewed by a multidisciplinary tumor board that included urologists, oncologists, radiologists, pathologists, and radiation oncologists before cryoablation was chosen. The cohort was predominantly male, with 39 men and 9 women, and the median age was 69.5 years, with patients ranging from 36 to 88 years old.

Papillary renal cell carcinoma is a distinct entity within the family of kidney cancers. While clear cell renal cell carcinoma is the most common histological type, papillary tumors account for roughly 10 to 15 percent of all renal cell carcinomas and are generally associated with better outcomes. The World Health Organization formally listed the entity in its 2016 classification of renal tumors, and pathologists further divide papillary tumors into two subtypes: type 1, which tends to be slower growing and more indolent, and type 2, which carries more aggressive features such as higher tumor grade, necrosis, and lymphovascular invasion. In the French series, type 1 tumors dominated the cohort, making up 46 of the 53 lesions, or 88.8 percent, while type 2 tumors accounted for the remaining 11.2 percent.

The technical execution of the procedure reveals why cryoablation has become such a powerful tool in interventional oncology. All treatments were performed by experienced interventional radiologists under general anesthesia or sedation, with the patient staying in hospital. Using computed tomography or magnetic resonance imaging for guidance, the radiologists inserted between two and four thin cryoprobes, typically 15 to 17 gauge, directly through the skin and into the tumor. The number, type, and positioning of the probes were tailored to each tumor’s size, location, and morphology, with the goal of enveloping the entire tumor in a lethal ice ball that extended 5 to 10 millimeters beyond its visible margins. For MRI-guided procedures, the team used MRI-compatible probes and near real-time multiplanar MRI fluoroscopy, allowing them to watch the ice ball grow in three dimensions as it formed.

Each ablation followed a standardized freeze-thaw protocol: two freezing cycles of 10 minutes each, separated by a 10-minute passive thawing period. This repetition is critical to the biology of cryodestruction. Rapid freezing causes ice crystals to form inside and around cells, rupturing their membranes, while the thawing and refreezing cycles amplify vascular damage, cutting off the tumor’s blood supply and ensuring that cells at the margin of the ice ball, where temperatures are less extreme, are still lethally injured. When tumors sat close to vulnerable structures such as the bowel or the abdominal wall, the team performed hydro-dissection or pneumo-dissection, injecting fluid or gas to physically push those organs out of harm’s way. In one striking example described in the study, sterile gloves filled with warm saline were placed over the skin at the probe entry sites to prevent frostbite, because MRI-compatible cryoprobes are not insulated along their shafts.

The results were striking on nearly every measure. Technical efficacy, defined as the absence of contrast enhancement and tumor enlargement on imaging within three months of the procedure, was achieved in all 53 tumors, a 100 percent success rate in destroying the treated lesion. The overall complication rate was just 11 percent, and every single complication was minor, classified as grade 2 or lower on the standard Clavien-Dindo scale. No patient required hemodialysis after treatment, a crucial finding given that many of these patients already had compromised kidney function, and a quarter of the cohort had only a single kidney. The median hospital stay was three days, and the median procedure took 127 minutes.

Oncologic outcomes were equally impressive. Only three of the 53 tumors, or 5.7 percent, recurred locally during follow-up, with a mean time to recurrence of 36 months. Two of the recurrences occurred in type 1 tumors and one in a type 2 tumor, a difference that was not statistically significant but is consistent with the known biology of the more aggressive type 2 subtype, which in this study also carried higher International Society of Urologic Pathologists grade scores. Two of the three recurrences were successfully treated with a second cryoablation. When these salvage treatments were factored in, the five-year estimates for local recurrence-free survival reached 95.9 percent for primary treatment and 97.8 percent for secondary effectiveness. Most remarkably, cancer-specific survival and metastasis-free survival were both 100 percent: no patient died of papillary renal cell carcinoma, and no patient ever developed distant metastases. Overall survival at five years was 90.3 percent, with the deaths that did occur attributable to unrelated cancers such as gastric, lung, and duodenal malignancies.

Perhaps the most provocative comparison in the study is with surgery itself. The authors point to a large surgical series of 626 patients with papillary renal cell carcinoma treated with partial nephrectomy, in which five-year cancer-specific survival was 83 percent, local recurrence-free survival was 91 percent, and overall survival was 82 percent, all figures lower than those reported in the cryoablation cohort. The authors are careful to caution against overinterpreting this comparison: there was no direct head-to-head analysis, the surgical series involved larger tumors averaging 4 to 5 centimeters compared with 2 to 3 centimeters in the ablation studies, and the sample sizes differ dramatically. Still, the findings add to a growing body of evidence that thermal ablation can match surgical outcomes for early-stage kidney tumors while avoiding the risks of major surgery, with prior studies showing fewer complications and shorter hospital stays for ablated patients.

The study does carry limitations that the authors acknowledge candidly. Its retrospective design and relatively small sample size, a consequence of the rarity of papillary renal cell carcinoma compared with the clear cell type, mean that larger multicenter studies will be needed to confirm the results. The effect of operator experience was not formally evaluated, although the authors note that their center performs more than 60 renal cryoablations per year, suggesting a consistently high standard of practice. The potential for inter- and intra-observer variability in imaging assessments was also not eliminated. And because the cohort was dominated by type 1 tumors, the findings for the more aggressive type 2 subtype rest on only seven lesions, a reminder that subtype-specific evidence remains thin.

Even with those caveats, the message for clinical practice is clear. For patients with biopsy-confirmed, localized papillary renal cell carcinoma who cannot undergo or decline surgery, percutaneous cryoablation delivered under image guidance offers a treatment that is safe, kidney-preserving, and, on the evidence of five years of follow-up, extraordinarily effective. The authors suggest that when treating type 2 tumors, radiologists should aim for larger ablation safety margins to account for their more aggressive biology. As interventional oncology continues to mature, they argue, cryoablation for renal cell carcinoma, particularly for indolent histologic subtypes like papillary tumors, deserves increased consideration in clinical practice and in future guideline development. For a disease increasingly caught early by incidental imaging, the freezer may prove to be as mighty as the scalpel.

Subject of Research: Percutaneous cryoablation as a treatment for papillary renal cell carcinoma

Article Title: Safety and oncologic efficacy of percutaneous cryoablation of papillary renal cell carcinoma: a 5-year single-center follow-up study

Article References: Mulot, B.-M., de Marini, P., Tan, A. S. M., Orkut, S., Garnon, J., Weiss, J., Autrusseau, P. A., Tricard, T., Lang, H., Cazzato, R. L., & GANGI, A. (2025). Safety and oncologic efficacy of percutaneous cryoablation of papillary renal cell carcinoma: a 5-year single-center follow-up study. CVIR Oncology, 1(1), Article 4. https://doi.org/10.1007/s44343-025-00003-5

Image Credits: AI Generated

DOI: 10.1007/s44343-025-00003-5

Keywords: cryoablation, papillary renal cell carcinoma, kidney cancer, interventional radiology, renal tumors, minimally invasive treatment, oncology, MRI guidance, CT guidance, cancer survival, thermal ablation, nephron-sparing

The research, published in CVIR Oncology by a team led by Maria Tækker of Aarhus University Hospital, examined percutaneous cryoablation, a technique in which thin, needle-like probes are inserted through the skin directly into a tumor under computed tomography guidance. Once the probes are in position, pressurized argon gas is circulated through their tips, dropping the temperature at the tumor to at least minus 40 degrees Celsius. At that extreme cold, ice crystals form inside and around cancer cells, rupturing membranes and cutting off the blood supply, ultimately killing the tissue through a process of controlled necrosis. Because the expanding ice ball is visible on CT scans as it grows, the radiologist can watch the frozen zone engulf the tumor in real time, ensuring the lethal cold extends at least five millimeters beyond the tumor’s edge while sparing nearby healthy structures.

This real-time visibility is one of cryoablation’s most significant advantages over competing ablative technologies, and it carries a second benefit that is easy to overlook: the procedure can be repeated. Unlike stereotactic body radiation therapy, where cumulative radiation dose limits how many times a region can be treated, or surgery, where each operation adds scar tissue and risk, cryoablation leaves tissue in a state that can safely tolerate another freeze cycle if a tumor returns. For patients with oligometastatic disease, the intermediate state between localized and widespread cancer in which only a limited number of metastases exist in a few organ sites, that repeatability could prove decisive.

The Danish team set out to test exactly that proposition in a group of patients who had run out of conventional options. Between December 2016 and February 2022, sixteen patients with fewer than three histologically verified metastases each were selected for treatment at a single center. Crucially, every case was reviewed by a multidisciplinary team of oncologists, surgeons, pathologists, and radiologists, and all of the patients had already completed treatment for their primary cancers. Many carried significant comorbidities: the most common were hypertension and diabetes, and the average score on the American Society of Anesthesiologists physical status scale, which grades surgical risk, was 2.6, indicating severe systemic disease in several participants. These were not healthy patients; they were people whose age or health made surgery, additional radiation, or more chemotherapy too dangerous, leaving cryoablation as the only feasible curative-intent option.

The technical execution of the procedures reflects the maturity the field has reached. A senior radiologist with a decade of experience in CT-guided interventions performed the ablations, most of them, 73.7 percent, under conscious sedation rather than general anesthesia. Using an argon-based cryoablation system with sealed 14- or 17-gauge cryoprobes, the team created ice balls that covered each tumor with a margin of at least five millimeters. Standard treatments used a double freeze-thaw cycle of ten minutes of freezing followed by eight minutes of thawing, a rhythm that exploits the way repeated freezing damages cells more thoroughly than a single cycle. Lymph node metastases received a triple freeze-thaw protocol, and when tumors sat close to vulnerable structures, the team used hydrodisplacement, injecting fluid to physically push organs such as the bowel away from the freezing zone.

The results, drawn from fifteen patients and sixteen metastases with complete follow-up, are striking for a cohort this fragile. The median tumor size was 18 millimeters, though lesions ranged from 6 to 60 millimeters, and the primary cancers originated in the kidney, lung, and breast. After a single cryoablation treatment, 80 percent of patients achieved local tumor control at a median follow-up of 23.6 months. Three patients whose tumors progressed underwent repeat ablations, and after these retreatments the so-called secondary efficacy rate rose to 93 percent at a median follow-up of 28.7 months. In other words, even when the first freeze failed to eradicate a lesion permanently, freezing it again usually finished the job, validating the technique’s key selling point of repeatability.

The safety profile was equally encouraging. Ninety percent of patients went home the same day. Of the nineteen treatments performed, only two produced post-procedural complications, and just one patient needed overnight hospitalization for monitoring. Graded on the Common Terminology Criteria for Adverse Events scale, complications were limited to grade 1 in 16 percent of procedures and grade 2 in 5 percent, with nothing more severe, and no complication required further intervention. For a population of comorbid patients with stage IV cancer, avoiding the morbidity of surgery or the accumulating toxicity of repeat radiation while still achieving local tumor control represents a genuine clinical gain.

Survival figures rounded out the picture. At one year, 93 percent of patients were alive; at two years, 72 percent; and at three years, 63 percent. The deaths that occurred were attributed to progression of the primary cancers rather than to the procedure itself. These numbers sit comfortably within the range reported by comparable studies, which have shown two-year overall survival of 82 to 94 percent and three-year survival of roughly 62 to 82 percent for metastasis-directed cryoablation. A recent retrospective analysis of 511 patients with lung metastases by Gits and colleagues found no significant survival differences between sublobar resection, stereotactic body radiation therapy, and percutaneous ablation, suggesting that needle-based approaches can stand alongside established local therapies. Meanwhile, literature on radiation-directed treatment of oligometastases indicates that such metastasis-directed therapy may extend expected survival by up to fifteen months, underscoring the stakes of getting local control right.

The study’s authors are candid about its limits. With only fifteen analyzed patients, a retrospective design, and a single center, the findings cannot be generalized blindly, and the inclusion of patients with advanced cancer and high anesthetic risk scores may actually understate the survival that healthier candidates could expect. Tumor size also emerged as a question mark: prior research suggests lesions larger than 20 millimeters carry a higher risk of local progression after cryoablation, and while this study’s tumors ranged well beyond that threshold, the sample was too small to settle the matter. What the data do support is a consistent pattern across diverse anatomical sites, from kidneys and adrenal glands to retroperitoneal soft tissue, lymph nodes, and even the iliac bone, that percutaneous cryoablation is an effective and repeatable method for managing limited metastatic disease over at least a two-year horizon.

The broader significance of the work lies in what it offers patients who have been told their options are exhausted. For someone with two or three metastases and a heart too weak for surgery, a same-day procedure that freezes their tumors under light sedation, with a 93 percent chance of lasting local control after retreatment and no serious complications, changes the calculus of stage IV cancer. The researchers argue that future clinical trials should evaluate overall survival together with quality of life, since both metrics capture what matters most when life is extended at advanced disease stages. High-level randomized evidence comparing cryoablation directly with radiation therapy for oligometastatic disease is still missing, but studies like this one, built on careful multidisciplinary selection, standardized reporting, and honest accounting of failures, are laying the groundwork. For now, the message is simple and quietly revolutionary: sometimes the best answer to a spreading cancer is not more drugs or bigger operations, but a precisely guided blast of cold, delivered through a needle, and repeated as often as needed.

Subject of Research: Percutaneous cryoablation as metastasis-directed therapy for oligometastatic cancer

Article Title: Percutaneous imaging-guided cryoablation of oligometastases – a single-center experience

Article References: Tækker, M., Pietersen, P. I., Junker, T., Jensen, C. G., Vogsen, M., Rasmussen, B. S., Welch, B. T., Persson, G. F., Al-Mashhadi, R., & Graumann, O. (2025). Percutaneous imaging-guided cryoablation of oligometastases – a single-center experience. CVIR Oncology, 1(1), Article 11. https://doi.org/10.1007/s44343-025-00011-5

Image Credits: AI Generated

DOI: 10.1007/s44343-025-00011-5

Keywords: cryoablation, oligometastatic disease, metastases, interventional radiology, CT guidance, cancer treatment, local tumor control, overall survival, minimally invasive therapy, kidney cancer, lung cancer, breast cancer

The study, published in CVIR Oncology as an open-access short communication, enrolled 97 patients with primary or secondary liver malignancies, of whom 74 completed the final analysis. All participants were treated under conscious sedation with analgesia rather than general anesthesia, and all were interviewed systematically about their pain experience at three distinct time points: during catheter placement under CT fluoroscopy, at the time of radiation delivery when the catheters were removed, and later the same evening on the ward. Pain was scored on the standard numeric rating scale from zero, meaning no pain, to ten, meaning maximum pain. The researchers also tracked age, sex, the number of lesions and catheters, prior treatments, tumor volume, tumor location, and complications classified according to Society of Interventional Radiology guidelines.

The technical choreography of the procedure helps explain why the anesthesia question matters so much. Unlike thermal ablation, where a probe is inserted and the tumor is burned or frozen in a single session, CT-guided HDR brachytherapy unfolds in two stages separated by a change of location. First, under CT fluoroscopic guidance, the interventionalist percutaneously places brachytherapy applicators into and around the tumor while the patient receives intravenous midazolam and fentanyl alongside local lidocaine anesthesia at the puncture site. A second physician stands by throughout, monitoring vital signs and titrating medication. Once the catheters are positioned and the planning scan is complete, the puncture sites are sterilely covered and the patient is escorted to a dedicated radiation operating room, where the iridium-192 source delivers its dose. Only after irradiation are the catheters removed, creating a second moment of potential discomfort, and the patient is then observed for roughly an hour before transfer to the regular ward.

The pain data that emerged were strikingly reassuring. At catheter placement, the moment many clinicians would expect to hurt most, 74.5 percent of patients rated their pain as low, in the zero-to-two range, while 19.0 percent reported moderate pain and only 6.5 percent severe pain. At the time of radiation and catheter removal, the picture improved further: 84.0 percent reported low pain, 11.0 percent moderate, and 5.5 percent severe. On the ward afterward, 79.5 percent reported low pain, 16.0 percent moderate, and 4.0 percent severe. The median doses of sedation were modest, 112.5 micrograms of fentanyl and 2 milligrams of midazolam, underscoring how little pharmacological support the procedure actually demands when performed with careful local anesthesia and image guidance.

Two patterns within the data carry practical weight for clinicians. Women reported significantly higher pain at the time of irradiation, with a p-value below 0.001, and the number of treated lesions was associated with significantly higher pain levels at two of the three measured time points, with p below 0.05. No other parameter, including age, tumor volume, tumor location, or the number of prior treatments, showed a significant relationship with pain perception. The authors suggest that these findings point to patient groups, women and those with multiple lesions, who may warrant heightened attention and more aggressive pain management during brachytherapy, rather than a wholesale change in the sedation strategy.

Safety outcomes were equally encouraging. Across three months of follow-up, mild to moderate complications occurred in 23.0 percent of patients, consisting mainly of pain and fever, while no major complications were observed at all. Patient satisfaction, measured on a ten-point scale from complete dissatisfaction to complete satisfaction, was overwhelmingly positive: 98.5 percent of patients scored their experience at seven or higher, and only a single patient recorded the lowest possible score. For a procedure involving the percutaneous puncture of the liver, the placement of multiple catheters, and the delivery of a high radiation dose directly into malignant tissue, a zero rate of major complications in 74 patients is a result that demands attention.

The biological logic of the technique may partly explain why patients tolerate it so well. Unlike radiofrequency or microwave ablation, where heat generation within the liver can be genuinely painful and respiratory movement during the procedure can compromise both safety and effectiveness, the radiation delivered by an HDR iridium-192 source is itself painless. This, the authors note, potentially accounts for the absence of any significant association between tumor location and pain perception in their data. The trade-off is time and logistics: the procedure takes longer than thermal ablation because of the transfer to the radiation room and the delayed catheter removal, and it is precisely this duration and change of setting that makes conscious sedation arguably more practicable than general anesthesia, avoiding the overhead, risks, and resource demands of an anesthesiology team.

The broader context makes the finding timely. Minimally invasive tumor ablation has surged to an all-time high, driven in part by landmark randomized evidence that thermal ablation can match surgical resection for small colorectal liver metastases, and by emerging navigation techniques such as stereotactic puncture that are expanding what image-guided interventions can achieve. Previous work has shown that HDR brachytherapy achieves high rates of local tumor control without strict limitations on tumor size or location, including ablation of large and very large hepatocellular tumors and of lesions with portal vein tumor thrombosis. As the technique moves toward broader adoption, the anesthesia protocol becomes a genuine bottleneck or enabler: if every case requires general anesthesia, throughput is limited and costs rise, whereas a protocol that keeps the patient comfortable while awake can be integrated directly into the clinical routine of an interventional radiology unit.

The study’s authors are candid about its limitations. It was a single-center, monocentric investigation without a comparative arm, and it relied on patient interviews and structured questionnaires, which introduces the possibility of recall bias, since patient-reported data may be influenced by the timing of assessment. The absence of a general anesthesia comparison group means the study cannot definitively settle the ongoing global debate about the optimal anesthesia method for liver ablation, a debate that until now has drawn almost exclusively on hyperthermal ablation procedures rather than brachytherapy. Some studies have even suggested that general anesthesia might offer oncological advantages, although the authors argue that factors such as tumor location and size likely play a more significant role in outcomes than the sedation technique itself.

Even with those caveats, the conclusion is clear and consequential: CT-guided HDR brachytherapy under conscious sedation with analgesia, performed by interventional radiologists themselves, is safe, feasible, and well tolerated, with low subjective pain, near-universal patient satisfaction, and no major complications. Beyond the immediate clinical benefit for patients with liver malignancies, the finding carries a professional significance for the field. Delivering conscious sedation within the interventional radiology unit, without dependence on anesthesiology services, strengthens the specialty’s autonomy and supports its development as an independent clinical discipline. As the number of minimally invasive tumor ablations continues to climb across centers worldwide, this study suggests that the future of precision liver cancer radiation may be one in which patients remain awake, comfortable, and cared for by the same team that guides the catheters, plans the dose, and delivers the cure.

Subject of Research: Feasibility and safety of CT-guided high-dose-rate brachytherapy for liver tumors under conscious sedation with analgesia

Article Title: Feasibility and safety of CT guided high dose rate brachytherapy of liver tumors performed under conscious sedation with analgesia

Article References: Auer, T. A., Erforth, M. Z., Segger, L., Savic, L. J., Fleckenstein, F., Collettini, F., Fehrenbach, U., & Gebauer, B. (2025). Feasibility and safety of CT guided high dose rate brachytherapy of liver tumors performed under conscious sedation with analgesia. CVIR Oncology, 1(1), Article 26. https://doi.org/10.1007/s44343-025-00026-y

Image Credits: AI Generated

DOI: 10.1007/s44343-025-00026-y

Keywords: brachytherapy, liver cancer, interventional radiology, conscious sedation, CT guidance, hepatocellular carcinoma, iridium-192, pain management, tumor ablation, radiation oncology, patient safety, minimally invasive therapy

The report, led by interventional radiologist Charlie A. Hamm and colleagues, is framed as a technical roadmap rather than a large trial, but its results are striking in their consistency. Eleven patients, four women and seven men ranging in age from 34 to 77, underwent CT-guided dye-based marking of twelve lung nodules before minimally invasive, lung-sparing resection. The median nodule diameter was just 8.5 millimeters. Every single marking procedure was technically successful, every lesion was completely resected, and no operation had to be converted to open surgery or an entire lobectomy because the surgeon could not find the target. Seven of the twelve lesions turned out to be malignant, underscoring how much rides on getting the localization right.

The clinical backdrop explains why this matters. Randomized screening trials such as the Dutch-Belgian NELSON study showed that volume-based CT screening reduces lung cancer mortality, and more recent cohort work like the SUMMIT study has confirmed that the majority of screen-detected cancers are diagnosed at stage I or II, when surgery is the primary treatment. That shift has pushed thoracic surgeons toward sublobar resection, removing a wedge of lung or a single segment rather than the whole lobe, to preserve as much healthy parenchyma as possible. But the smaller the lesion and the more tissue-sparing the operation, the more critical it becomes to know exactly where the target sits before the first incision is made.

The traditional answer has been the hook-wire, a thin barbed wire placed through the chest wall into or next to the nodule on the morning of surgery. Hook-wires work, but they come with real drawbacks. They typically force same-day scheduling of two procedures, they can dislodge or migrate before the surgeon reaches them, and a rigid wire protruding through the pleura is uncomfortable and potentially hazardous for the patient, who must be transported carefully to avoid tearing lung tissue. The Berlin team’s dye-based approach eliminates the transpleural hardware entirely, which the authors note has been reported to cause less patient discomfort and stress and reduces the risk of marker displacement.

The first of the two dye techniques relies on patent blue V, a synthetic triphenylmethane dye that has long been used to trace lymphatic drainage in breast surgery and melanoma staging. It is water-soluble, renally excreted, and has a low toxicity profile, with allergic reactions occurring in fewer than one percent of patients. Under CT-fluoroscopic guidance, the radiologist advances a fine 22-gauge Chiba needle until its tip sits immediately adjacent to the nodule, deliberately avoiding puncture of the lesion itself, which reduces the theoretical risk of tumor seeding along the needle track and avoids compromising the pathology specimen. Then 0.1 to 0.4 milliliters of dye is injected through a small Luer-lock syringe, and the needle is withdrawn promptly without a saline flush, which would dilute the dye and could tattoo the skin along the exit path.

What happens next is a matter of physics and anatomy. The dye diffuses through the terminal vascular bed of the lung and reaches the pleural surface, where it creates a sharply demarcated blue patch that tells the surgeon precisely where the resection margin should fall. If the lesion lies more than three centimeters beneath the pleura, the dye is injected in increments as the needle is withdrawn, leaving a stained tract running from the nodule toward the chest wall. Because patent blue V gradually disperses into the bloodstream and pleural fluid, the color fades within hours, so surgery must be scheduled the same day, ideally within three hours of the marking. In the Berlin series, the five patients who received patent blue V injections had a median marking time of just seven minutes.

The second technique solves the fading problem with indocyanine green, or ICG, a tricarbocyanine fluorescent dye that binds readily to tissue proteins and glows bright emerald green when excited by near-infrared light. Injected alone, ICG diffuses more slowly than patent blue V and can remain visible in lung tissue for up to six days, a finding documented in prior experimental work. More importantly, near-infrared light penetrates soft tissue far better than visible light, so a fluorescence camera in the operating room can detect the glowing signal from millimeters to several centimeters beneath the pleural surface, effectively letting the surgical team see through the lung’s outer rim to a depth of roughly three centimeters. The six patients in the series who received ICG-based marking had a median procedure time of 16.5 minutes.

The most innovative variant described in the report goes one step further: instead of injecting liquid dye that will eventually disperse, the team deploys a tiny embolization coil soaked in ICG. The preparation is meticulous. ICG is mixed with ten milliliters of sterile water, and two to three milliliters of the solution are used to slowly flush the coil introducer outside the patient to prevent premature deployment. The markers are Tornado-type coils measuring 0.035 inches in diameter and 7 to 8 millimeters in length. After percutaneous puncture with an 18-gauge coaxial needle, the coil is advanced with the stiff end of a guidewire and deployed under CT-fluoroscopy immediately adjacent to the lesion, with care taken not to push it too far past the target. The coil acts as a physical scaffold that holds the dye in place, and because the fluorescence persists for days, surgery can be scheduled up to thirteen days after marking, giving hospitals valuable flexibility when operating rooms are crowded or schedules shift unexpectedly.

Safety data from the series align with the broader literature. Only one complication occurred, an asymptomatic pneumothorax during needle puncture that was managed conservatively without any intervention, consistent with reported pneumothorax rates of around six percent for CT-guided ICG injection in a retrospective analysis of 471 patients. The authors do caution that coil placement requires a larger 18-gauge needle than pure dye injection, which may influence complication rates. Prior studies have reported technical success rates above 98 percent for CT-guided dye injection and 100 percent for bronchoscopy-guided ICG-coil placement, and the addition of preoperative markings has been shown in other reports to drive conversion rates to open surgery close to zero.

What makes the Berlin report notable is the delivery route. ICG-soaked coil marking had previously been described through bronchoscopy, a technique that requires general anesthesia and specialized endoscopic equipment, and only recently through a percutaneous approach. The CT-guided percutaneous route can be performed in an outpatient workflow under local anesthesia alone, making it less resource-intensive and easier to slot into a busy hospital schedule. The authors emphasize that the technique is ultimately a story about multidisciplinary collaboration: the tumor board decides the patient needs lung-sparing surgery, the interventional radiologist plants the beacon, and the thoracic surgeon follows the glow. As robotic-assisted and uniportal thoracoscopic surgery become more common and screening programs continue to surface ever-smaller nodules, dye-based marking may become a routine bridge between the radiology suite and the operating room, turning invisible targets into ones a surgeon cannot miss.

Subject of Research: CT-guided preoperative dye-based marking of small lung nodules for minimally invasive surgical resection

Article Title: CT-guided percutaneous marking of lung nodules using patent blue V and indocyanine green

Article References: Hamm, C. A., Elsner, A., Fehrenbach, U., Savic, L. J., Bawaadam, H., Collettini, F., Neudecker, J., Gebauer, B., Rückert, J., & Auer, T. A. (2026). CT-guided percutaneous marking of lung nodules using patent blue V and indocyanine green. CVIR Oncology, 2(1), Article 2. https://doi.org/10.1007/s44343-026-00031-9

Image Credits: AI Generated

DOI: 10.1007/s44343-026-00031-9

Keywords: lung nodules, interventional radiology, indocyanine green, patent blue V, CT guidance, thoracic surgery, fluorescence imaging, preoperative localization, lung cancer screening, video-assisted thoracoscopic surgery, fiducial coils, lung-sparing resection

Liver biopsy is a cornerstone of cancer diagnosis, but it is far from trivial. The liver is a crowded, vascular organ hemmed in by ribs, lungs, bowel, and major blood vessels, and the needle must reach a target lesion while avoiding all of these hazards. Today, that planning rests almost entirely on the experience and judgment of individual interventional radiologists, which introduces meaningful variability between operators. Standardized AI-assisted planning has been proposed as a way to reduce that variability, particularly at centers with less experienced staff, but the field remains preliminary. The Memorial Sloan Kettering team set out to test the most basic building block of such a system: could a generative AI model, given nothing but a single axial CT slice and a standardized prompt, propose an entry angle that experienced reviewers would rate as potentially safe?

The study design was deliberately simple. The researchers retrospectively collected de-identified CT images from 30 consecutive CT-guided liver biopsies performed between February and June 2025 by sixteen board-certified interventional radiologists with a median of eight years of experience. The patient group included 20 women and 10 men with a median age of 56, and their lesions spanned liver segments 1 through 8 under the Couinaud classification. Crucially, the AI never touched a patient. It worked only on the initial planning CT image, after the fact, and only in two dimensions, while the actual procedures had already been completed safely by human hands.

The preprocessing workflow was strikingly low-tech for a study of cutting-edge AI. Each CT image was cropped to remove patient identifiers, magnified without rescaling, and overlaid with a radial grid created in GIMP, the free open-source image editor. The grid consisted of 36 radial lines at 10-degree intervals with concentric circles spaced 10 millimeters apart, calibrated to known anatomical landmarks. The annotated images were saved as PNG files and fed to GPT-4.1 through a standardized prompt. The model operated entirely on its baseline training, with no fine-tuning on medical data, and a fresh chat was started for every case to prevent contamination between cases.

The researchers tested two conditions that differed in how much hand-holding the AI received. In the first condition, two study authors manually annotated each image with a blue circle marking the lesion and a red line delineating sensitive structures to avoid, essentially handing the model a pre-drawn map of the danger zones. In the second, more demanding condition, only the blue circle was drawn, forcing the AI to identify critical structures on its own. For each case, the model was allowed up to four iterations: if its proposed trajectory failed safety criteria, it was re-prompted within that limit. Two independent reviewers then rated every AI-generated trajectory using consensus methodology, judging safety, avoidance of organs, vessels, and bone, whether the path crossed the midline or excessive tissue, and whether the approach would be comfortable and clinically reasonable.

The headline numbers were encouraging, with important caveats. In the first condition, the AI needed a median of two iterations and produced trajectories rated potentially safe in 27 of 30 cases, or 90 percent. In the second condition, without the red-line annotations, it needed a median of just one iteration and scored 28 of 30, or 93 percent. The difference between conditions was not statistically significant, and the model’s proposed entry angles differed significantly from the angles actually used by clinicians, with mean differences reaching statistical significance in both conditions. Only 23 percent of cases in condition one and 33 percent in condition two showed strong concordance, defined as entry angles within 10 degrees with similar liver traversal patterns, meaning the AI was often safe but not necessarily matching human choices.

The failures are as instructive as the successes. In three cases in the first condition, the AI proposed paths crossing bone, the midline, or the marked red line, even after four attempts. One of these involved a patient with ascites, fluid in the abdomen that complicated the anatomy; another involved a patient whose prior surgery had removed the left hepatic lobe, creating atypical anatomy; and a third targeted a high-lying segment 2 lesion where the model routed the needle through costal cartilage. Cartilage proved a recurring blind spot: in the second condition, both unsafe trajectories involved bone or cartilage, suggesting the model struggles to recognize structures with intermediate radiodensity. The authors note that excluding these inadequate cases from distance calculations introduces selection bias that may flatter the AI’s performance.

On the metric of liver tissue traversed, the AI actually looked competitive. In condition one, its paths crossed a median of 31.6 millimeters of liver versus 48.25 millimeters for the manual paths, and in condition two, 39.35 versus 48.25 millimeters, though neither difference reached statistical significance. Interestingly, the AI’s longer median distances in the unannotated condition hint at a conservative streak: without predefined avoidance zones, it may favor longer but safer routes. A power analysis indicated the 30-case sample could only detect large effect sizes, so smaller but clinically meaningful differences would require larger cohorts to detect.

The authors are refreshingly blunt about what these results do not mean. This was a proof of concept, nothing more. The workflow does not address a real clinical need: interventional radiologists can identify safe trajectories in seconds using native console capabilities with full three-dimensional visualization, whereas the AI pipeline required manual image export, GIMP annotation, and chatbot prompting, all while discarding the three-dimensional spatial information that real planning depends on. A human planner scrolls through multiple slices, uses multiplanar reconstruction, and mentally constructs 3D anatomy, capabilities entirely absent from a static 2D analysis. The AI also required continuous human supervision, with iterative re-prompting in most cases, which undermines any claim of autonomy. And because the AI trajectories were never actually executed, they remain theoretical, while the manual paths were proven safe by successful, complication-free procedures, a comparison that cannot establish equivalence.

Looking forward, the researchers see a path, if a long one. Future systems would need automated lesion identification, since current generative models lack the segmentation capabilities required for precise localization, and integration with dedicated segmentation architectures such as U-Net could enable fully autonomous planning from raw CT images. Three-dimensional volumetric analysis, quantitative vascular proximity measurements, phantom studies, and prospective multicenter trials would all be prerequisites before any clinical consideration. The authors also point toward applications in tumor ablation and margin assessment, and note that many liver biopsies worldwide are performed under ultrasound guidance, where real-time, operator-dependent imaging poses an even harder challenge for AI. For now, the message is measured: generative AI can look at a liver CT slice and propose a plausible needle angle most of the time, but the 7 to 10 percent of cases where it fails, sometimes by routing a needle through bone or cartilage, are exactly the cases where a patient would be harmed. In medicine, that margin is everything.

Subject of Research: Feasibility of generative AI for planning CT-guided liver biopsy needle trajectories

Article Title: Feasibility of generative AI for CT-guided liver biopsy trajectory planning: a pilot study

Article References: Feasibility of generative AI for CT-guided liver biopsy trajectory planning: a pilot study. (n.d.). https://doi.org/10.1007/s44343-026-00041-7

Image Credits: AI Generated

DOI: 10.1007/s44343-026-00041-7

Keywords: generative AI, GPT-4.1, liver biopsy, CT guidance, interventional radiology, trajectory planning, pilot study, medical imaging, needle biopsy, proof of concept, Memorial Sloan Kettering, artificial intelligence