The study was conducted by researchers who analysed data generated by one manufacturer, Quanovate Tech Inc., in its facilities. Testing took place over four days with five operators and followed each manufacturer’s instructions. Four devices formed five evaluated configurations: three reader-based systems with controlled lighting and two strip-based systems that used smartphone imaging. Each device-and-strip combination underwent 208 test runs.

The researchers evaluated luteinizing hormone (LH), follicle-stimulating hormone (FSH), estrone-3-glucuronide (E3G) and pregnanediol glucuronide (PDG). Artificial urine was prepared with standard concentrations of these hormones, and pH and specific gravity were checked for matrix consistency. Precision was assessed using coefficients of variation (CV), while accuracy was evaluated through relative deviation (RD) from the expected concentration. The researchers also examined linearity, limit of blank (LoB), limit of detection (LoD), ambient-light effects for the smartphone-based strips and responses to potentially interfering hormones.

The experiments were informed by Clinical and Laboratory Standards Institute validation principles but did not constitute full CLSI-compliant validation. The study used 10 replicate measurements at each concentration for several precision and accuracy tests, with five concentration levels for linearity and 20 replicates for blank and low-concentration samples. Because many replicates came from a single instrument or lot, the authors said the device comparisons should be interpreted as descriptive rather than as generalizable differences between devices. A full validation would also require between-day, between-run, lot-to-lot and instrument-to-instrument comparisons.

Performance varied by device and analyte. Across the tested concentrations, CV and RD values ranged from near the study’s 15% interpretation benchmark to levels exceeding 50% at some concentrations. For LH, the Device 2a and Device 2b configurations produced CV and RD values generally at or near, or below, 15% at most tested concentrations. Device 1, although also reader-based, exceeded the 15% threshold for LH and FSH at most concentrations; its FSH result was acceptable at the lowest tested concentration. Other systems also frequently exceeded the threshold. For E3G, Device 1 had low CV but marked systematic bias, with RD values of 97% to 322% relative to the spiked concentrations.

Linearity results also differed substantially. All five configurations had high coefficients of determination for LH, but Device 2a alone had a slope close to 1 and a maximum allowable deviation from linearity of 8.4%. For E3G, the coefficients of determination were 0.04 for Device 3 and 0.01 for Device 4, indicating little observed linear relationship between expected and measured concentrations in the tested range. Device 2a had the lowest E3G maximum allowable deviation, at 12.7%. For PDG, Device 1 and Device 2a had coefficients of determination of 0.93 and 0.90, respectively.

Detection limits also varied. For LH, Devices 1, 3 and 4 had LoB values of 0.00 to 0.10 mIU/mL, compared with 3.11 mIU/mL for Device 2a and 0.69 mIU/mL for Device 2b. Devices 1, 2a and 2b had near-zero LoB values for E3G, while the other systems produced higher blank readings. Against a 50 ng/mL clinical threshold for E3G, two devices had LoDs near or below that level, while the remaining devices exceeded it. For PDG, Devices 1 and 2 showed minimal blank noise, and the other configurations had progressively higher LoBs and LoDs.

Ambient lighting affected the two smartphone-based strip systems, particularly at lower hormone concentrations. Tests were conducted under regular ambient light, 50 lux and 300 lux. Device 3 showed significant deviations from ambient conditions only for low-concentration LH. Device 4 was more affected: LH results differed significantly under bright and dark conditions at 12.5 and 25 mIU/mL, while PDG readings showed pronounced light-dependent variability at lower concentrations.

Specificity testing identified the clearest cross-reactivity when LH channels were challenged with 100 mIU/mL hCG. All configurations except Device 4 showed significant LH cross-reactivity, indicating the possibility of a false LH result in the presence of hCG. Device 4, which measures the LH beta subunit, showed no detectable LH response at that concentration. Cross-reactivity involving thyroid-stimulating hormone, cortisol, pregnenolone, 17α-hydroxyprogesterone and progesterone was described as minimal and clinically inconsequential. The artificial-urine matrix did not reproduce all features of human urine, including variable pH, salts, proteins and hydration status. The findings therefore do not establish clinical validity, ovulation detection, fertile-window estimation or menstrual-phase classification. The authors call for independent replication, testing with human urine and longitudinal clinical studies with appropriate ovulation reference standards.

Subject of Research: Analytical performance of quantitative at-home urinary hormone monitoring systems tested in artificial urine

Article Title: Preliminary laboratory analytical comparison of quantitative at-home urinary hormone monitoring systems using artificial urine

Article References: Bouchard, T. P., Yong, P. J., & Doyle-Baker, P. K. (2026). Preliminary laboratory analytical comparison of quantitative at-home urinary hormone monitoring systems using artificial urine. Frontiers in Endocrinology, 17, Article 1947016. https://doi.org/10.3389/fendo.2026.1947016

Image Credits: AI Generated

DOI: 10.3389/fendo.2026.1947016

Keywords: at-home hormone monitoring, urinary hormone assays, analytical validation, artificial urine, precision and accuracy, luteinizing hormone, hCG cross-reactivity, fertility tracking, device comparison, Preliminary, laboratory, analytical

The study, published as a short communication in CVIR Oncology, analyzed isotherm charts from three FDA-certified cryoablation systems: two argon-based Joule–Thomson platforms, Boston Scientific’s System A and Endocare/Varian’s System B, and a liquid nitrogen system, IceCure Medical’s System C. All measurements had been performed in ultrasonic gels under standardized conditions, with 216 data points covering single needles and clustered needle configurations. The authors defined the LIR as the width of the −20 °C or −40 °C isotherm divided by the width of the visible ice ball, expressed as a percentage. A higher ratio means a larger share of the frozen zone is cold enough to guarantee cell death.

The physics behind the metric is rooted in how cells die under extreme cold. Below −40 °C, intracellular ice crystals form and physically shred cellular structures, triggering immediate necrosis. At temperatures as high as −20 °C, secondary mechanisms come into play, including osmotic stress and ischemic injury that starve tissue of blood supply. Because these lethal zones cannot be seen during a procedure, operators currently rely on the visible ice ball diameter and probe spacing as proxies, a practice the authors argue leaves a dangerous margin of uncertainty that can lead to inadequate tumor coverage and local recurrence.

The results were striking. Across all systems, isotherm widths correlated strongly and linearly with ice ball size, with correlation coefficients ranging from 0.880 to 0.999. But the proportion of lethal territory within the ice ball differed dramatically by technology. The liquid nitrogen System C achieved the highest ratios, with the −20 °C isotherm spanning 80.6 percent of the ice ball on average and the −40 °C isotherm covering 60.3 percent. The argon-based Systems A and B trailed significantly, both reaching about 69.6 percent at −20 °C, while their −40 °C ratios fell to 44 percent and 51.4 percent respectively, differences the authors report as statistically significant.

The explanation lies in the cooling technologies themselves. Joule–Thomson systems drop their temperature by expanding high-pressure argon gas, at 3200 PSI, through a throttling orifice, a process that supports multiple cryoprobes working in parallel. Liquid nitrogen systems operate at far lower pressures, around 100 PSI, but reach colder temperatures faster. The trade-off, the study notes, is that liquid nitrogen systems may struggle with very large ice balls, where peripheral warming erodes the lethal core, while clustered cryoprobes enhance energy removal but demand more complex insertion techniques.

That trade-off produced the study’s most clinically actionable finding: a threshold effect at roughly 45 millimeters. Linear regression analysis showed that for ice balls smaller than about 45 mm in width, a single liquid nitrogen needle delivers larger lethal isotherms than any single argon needle. Beyond that threshold, the regression lines intersect and the picture reverses: clusters of Joule–Thomson needles produce bigger lethal zones, with an almost perfect correlation of 0.998 to 0.999. Notably, when System A’s needles were clustered, their LIRs rose to 79.3 percent at −20 °C and 60.9 percent at −40 °C, statistically indistinguishable from the liquid nitrogen system’s single-needle performance.

For interventional radiologists, the implications could reshape device selection and preoperative planning. If a tumor is expected to generate an ice ball under 45 mm, the data suggest a single liquid nitrogen probe may be the more efficient choice. For larger targets, clustered argon probes offer superior coverage. Because the LIR quantifies the relationship between what is visible on screen and the effective ablation zone, it could allow operators to estimate the required number of probes and their optimal spacing before the first incision, potentially shortening procedures and reducing complications. The finding that the −20 °C isotherm can encompass up to 80 percent of the ice ball even hints that real-time thermometry might become unnecessary if LIR values reliably predict ablation zones.

The metric also fills a gap in how the field compares competing technologies. Until now, manufacturers’ claims rested on raw ice ball dimensions and probe spacing, figures that say nothing about the lethal fraction of the frozen volume. By normalizing lethal isotherm widths to the visible freezing front, the LIR offers a common currency for benchmarking cryoprobes, needle gauges, and chamber lengths across vendors. The authors suggest it could become a standardized yardstick for regulators, buyers, and clinicians alike, in the same way that metrics like specific absorption rate structure comparisons in other energy-based therapies.

The study is not without caveats, and the authors are candid about them. All isotherm data came from ultrasonic gels, not living tissue. Biological tissue brings perfusion, heterogeneity, and variable thermal conductivity, all of which alter heat transfer in vivo and could shift LIR values in real patients. Testing conditions also varied somewhat between manufacturers, with ambient temperatures of 20 to 23 °C, probe depths of 2 to 3 cm, and freeze durations of 10 to 15 minutes, and although FDA certification imposed standardized protocols, cross-vendor methodological differences could introduce bias. The corresponding author has consulted for all three companies whose systems were analyzed, a potential conflict the authors state was mitigated through standardized data collection and analysis.

Future work, the team argues, should validate LIR against histologically confirmed ablation zones in animal and human tissue, run prospective trials comparing procedures planned with and without the metric, and build computational models that fold tissue-specific properties into the calculation. If those steps succeed, the Lethal Isotherm Ratio could transform a field that has long judged its instruments by the size of the ice they make rather than the death they deliver. For now, the message is clear: not all ice balls are created equal, and the difference between 44 percent and 80 percent lethal coverage may be the difference between a cured tumor and one that comes back.

Subject of Research: A standardized metric, the lethal isotherm ratio, for comparing cryoablation needles and systems based on lethal temperature zones within visible ice balls.

Article Title: Lethal isotherm ratio to standardize the comparison of cryoablation needles and systems

Article References: Cornelis, A. A., Bodard, S., & Cornelis, F. H. (2025). Lethal isotherm ratio to standardize the comparison of cryoablation needles and systems. CVIR Oncology, 1(1), Article 3. https://doi.org/10.1007/s44343-025-00004-4

Image Credits: AI Generated

DOI: 10.1007/s44343-025-00004-4

Keywords: cryoablation, lethal isotherm ratio, cryoprobes, liquid nitrogen, Joule-Thomson, interventional radiology, tumor ablation, isotherms, ice ball, device comparison, oncology, Lethal