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Background Progression-free survival (PFS) determined by Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) is the reference standard to assess efficacy of treatments in patients with clear cell renal cell carcinoma. Purpose To assess the most common components of radiologic progressive disease as defined by RECIST 1.1 in patients with clear cell renal cell carcinoma and how the progression events impact PFS. Materials and Methods This secondary analysis of the phase III METEOR trial conducted between 2013 and 2014 included patients with metastatic clear cell renal cell carcinoma, with at least one target lesion at baseline and one follow-up time point, who were determined according to RECIST 1.1 to have progressive disease. A chest, abdominal, and pelvic scan were acquired at each time point. Kruskal-Wallis analysis was used to test differences in median PFS among the RECIST 1.1 progression events. The Holm-Bonferroni method was used to compare the median PFS of the progression events for the family-wise error rate of 5% to adjust P values for multiple comparisons. Results Of the 395 patients (296 men, 98 women, and one patient with sex not reported; mean age, 61 years ± 10), 73 (18.5%) had progression due to non-target disease, 105 (26.6%) had new lesions, and 126 (31.9%) had progression of target lesions (defined by an increase in the sum of diameters). Patients with progression of non-target disease and those with new lesions had shorter PFS than patients with progression defined by the target lesions (median PFS, 2.8 months [95% confidence interval {CI}: 1.9 months, 3.7 months] and 3.6 months [95% CI: 3.3 months, 3.7 months] vs 5.4 months [95% CI: 5.0 months, 5.5 months], respectively [ P < .01]). Conclusion The most common causes for radiologic progression of renal cell carcinoma were based on non-target disease and new lesions rather than change in target lesions, despite this being considered uncommon in the Response Evaluation Criteria in Solid Tumors version 1.1 literature. © RSNA, 2019 See also the editorial by Kuhl in this issue.

Sentinel lymph node biopsy (SLNB) is commonly performed in cancers that metastasise via the lymphatic system. It involves excision and histology of sentinel lymph nodes (SLNs) and presents two main challenges: (i) sensitive whole-body localisation of SLNs, and (ii) lack of pre-operative knowledge of their metastatic status, resulting in a high number (>70%) of healthy SLN excisions. To improve SLNB, whole-body imaging could improve detection and potentially prevent unnecessary surgery by identifying healthy and metastatic SLNs. In this context, radiolabelled SPIOs and PET-MRI could find applications to locate SLNs with high sensitivity at the whole-body level (using PET) and guide high-resolution MRI to evaluate their metastatic status. Here we evaluate this approach by synthesising a GMP-compatible 68 Ga-SPIO ( 68 Ga-Sienna+) followed by PET-MR imaging and histology studies in a metastatic breast cancer mouse model. Methods. A clinically approved SPIO for SLN localisation (Sienna+) was radiolabelled with 68 Ga without a chelator. Radiochemical stability was tested in human serum. In vitro cell uptake was compared between 3E.Δ.NT breast cancer cells, expressing the hNIS reporter gene, and macrophage cell lines (J774A.1; RAW264.7.GFP). NSG-mice were inoculated with 3E.Δ.NT cells. Left axillary SLN metastasis was monitored by hNIS/SPECT-CT and compared to the healthy right axillary SLN. 68 Ga-Sienna+ was injected into front paws and followed by PET-MRI. Imaging results were confirmed by histology. Results. 68 Ga-Sienna+ was produced in high radiochemical purity (>93%) without the need for purification and was stable in vitro . In vitro uptake of 68 Ga-Sienna+ in macrophage cells (J774A.1) was significantly higher (12 ± 1%) than in cancer cells (2.0 ± 0.1%; P < 0.001). SPECT-CT confirmed metastasis in the left axillary SLNs of tumour mice. In PET, significantly higher 68 Ga-Sienna+ uptake was measured in healthy axillary SLNs (2.2 ± 0.9 %ID/mL), than in metastatic SLNs (1.1 ± 0.2 %ID/mL; P = 0.006). In MRI, 68 Ga-Sienna+ uptake in healthy SLNs was observed by decreased MR signal in T2/T2*-weighted sequences, whereas fully metastatic SLNs appeared unchanged. Conclusion. 68 Ga-Sienna+ in combination with PET-MRI can locate and distinguish healthy from metastatic SLNs and could be a useful preoperative imaging tool to guide SLN biopsy and prevent unnecessary excisions., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Objective: The objective of our study was to investigate the performance of relative enhancement on multiphasic MRI to differentiate clear cell renal cell carcinoma (RCC) from other RCC subtypes (papillary and chromophobe) and oncocytoma., Materials and Methods: For this study, we derived a cohort of 34 clear cell RCCs, nine oncocytomas, 12 papillary RCCs, and 10 chromophobe RCCs with a preoperative multiphasic dynamic contrast-enhanced MRI study with up to four phases (i.e., unenhanced, corticomedullary, nephrographic, excretory) from 2005 to 2016. These groups were evaluated for multiphasic enhancement and were compared using Kruskal-Wallis and Mann-Whitney tests. ROC curves were constructed and logistic regression analyses were performed to evaluate the performance of multiphasic enhancement in differentiating clear cell RCCs from the other three groups., Results: Clear cell RCCs exhibited significantly greater relative signal intensity compared with uninvolved renal cortex in the corticomedullary phase (mean, 2.9) than oncocytomas (-21.7, p = 0.001), papillary RCCs (-53.0, p < 0.001), and chromophobe RCCs (-21.0, p < 0.001). Relative signal intensity in the corticomedullary phase differentiated clear cell RCCs from oncocytomas with an AUC of 0.90 and with an accuracy of 84% (32/38), sensitivity of 90% (27/30), and specificity of 63% (5/8) after controlling for lesion size, patient age, and patient sex. Relative corticomedullary signal intensity differentiated clear cell RCCs from oncocytomas and other RCC subtypes with an AUC of 0.93 and with an accuracy of 90% (53/59), sensitivity of 90% (27/30), and specificity of 90% (26/29) after controlling for lesion size, patient age, and patient sex., Conclusion: Multiphasic MRI enhancement may assist in differentiating clear cell RCC from oncocytomas and other RCC subtypes, if validated in prospective studies.

Objective: Sentinel lymph node biopsy (SLNB) with a superparamagnetic iron oxide (SPIO) tracer was shown to be non-inferior to the standard combined technique in the SentiMAG Multicentre Trial. The MRI subprotocol of this trial aimed to develop a magnetic alternative for pre-operative lymphoscintigraphy (LS). We evaluated the feasibility of using MRI following the administration of magnetic tracer for pre-operative localization of sentinel lymph nodes (SLNs) and its potential for non-invasive identification of lymph node (LN) metastases., Methods: Patients with breast cancer scheduled to undergo SLNB were recruited for pre-operative LS, single photon emission CT (SPECT)-CT and SPIO MRI. T1 weighted turbo spin echo and T2 weighted gradient echo sequences were used before and after interstitial injection of magnetic tracer into the breast. SLNs on MRI were defined as LNs with signal drop and direct lymphatic drainage from the injection site. LNs showing inhomogeneous SPIO uptake were classified as metastatic. During surgery, a handheld magnetometer was used for SLNB. Blue or radioactive nodes were also excised. The number of SLNs and MR assessment of metastatic involvement were compared with surgical and histological outcomes., Results: 11 patients were recruited. SPIO MRI successfully identified SLNs in 10 of 11 patients vs 11 of 11 patients with LS/SPECT-CT. One patient had metastatic involvement of four LNs, and this was identified in one node on pre-operative MRI., Conclusion: SPIO MRI is a feasible technique for pre-operative localization of SLNs and, in combination with intraoperative use of a handheld magnetometer, provides an entirely radioisotope-free technique for SLNB. Further research is needed for the evaluation of MRI characterization of LN involvement using subcutaneous injection of magnetic tracer., Advances in Knowledge: This study is the first to demonstrate that an interstitially administered magnetic tracer can be used both for pre-operative imaging and intraoperative SLNB, with equal performance to imaging and localization with radioisotopes.

Axillary management in patients with breast cancer has become much less invasive with the introduction of sentinel lymph node biopsy (SLNB). However, over 70 % of SLNBs are negative, questioning the generic use of this invasive procedure. Emerging evidence indicates that breast cancer patients with a low axillary burden of disease do not benefit from axillary lymph node dissection (ALND). Non-invasive techniques such as paramagnetic iron oxide contrast-enhanced magnetic resonance imaging (MRI) may provide genuine alternatives to axillary staging and should be evaluated within clinical trials. Selective axillary surgery could then be offered based on imaging findings and for therapeutic intent. This non-operative approach would reduce morbidity further and facilitate interpretation of follow-up imaging. Key Points • Modern imaging and biopsy greatly help the axillary staging of breast cancer. • Superparamagnetic iron oxide (SPIO)-enhanced MRI offers a further advance. • Sentinel lymph node biopsy may become redundant with SPIO-enhanced MRI. • Selective therapeutic axillary surgery should be based upon preoperative imaging findings.

The spectrum of female urethral and periurethral disorders includes both benign and malignant entities. Establishing an accurate clinical diagnosis may be challenging because symptoms and physical findings frequently overlap among the various entities. Recent technologic advances in magnetic resonance (MR) imaging and ultrasonography (US) allow more detailed evaluation of urethral and periurethral abnormalities. Advances in MR imaging hardware and pulse sequences allow high-resolution, high-contrast static and dynamic imaging of the female urethral and periurethral region in the context of the entire pelvic floor. Similarly, the introduction of high-resolution surface and intracavitary transducers in conjunction with three-dimensional acquisition have enhanced the role of US in this clinical setting. High-resolution MR imaging and real-time US have exciting potential as tools for more comprehensive analysis of the pathophysiologic features of the complex disorders that affect the female urethra and periurethral tissues., (© RSNA, 2010.)

Background Various limitations have impacted research evaluating reader agreement for Liver Imaging Reporting and Data System (LI-RADS). Purpose To assess reader agreement of LI-RADS in an international multicenter multireader setting using scrollable images. Materials and Methods This retrospective study used deidentified clinical multiphase CT and MRI and reports with at least one untreated observation from six institutions and three countries; only qualifying examinations were submitted. Examination dates were October 2017 to August 2018 at the coordinating center. One untreated observation per examination was randomly selected using observation identifiers, and its clinically assigned features were extracted from the report. The corresponding LI-RADS version 2018 category was computed as a rescored clinical read. Each examination was randomly assigned to two of 43 research readers who independently scored the observation. Agreement for an ordinal modified four-category LI-RADS scale (LR-1, definitely benign; LR-2, probably benign; LR-3, intermediate probability of malignancy; LR-4, probably hepatocellular carcinoma [HCC]; LR-5, definitely HCC; LR-M, probably malignant but not HCC specific; and LR-TIV, tumor in vein) was computed using intraclass correlation coefficients (ICCs). Agreement was also computed for dichotomized malignancy (LR-4, LR-5, LR-M, and LR-TIV), LR-5, and LR-M. Agreement was compared between research-versus-research reads and research-versus-clinical reads. Results The study population consisted of 484 patients (mean age, 62 years ± 10 [SD]; 156 women; 93 CT examinations, 391 MRI examinations). ICCs for ordinal LI-RADS, dichotomized malignancy, LR-5, and LR-M were 0.68 (95% CI: 0.61, 0.73), 0.63 (95% CI: 0.55, 0.70), 0.58 (95% CI: 0.50, 0.66), and 0.46 (95% CI: 0.31, 0.61) respectively. Research-versus-research reader agreement was higher than research-versus-clinical agreement for modified four-category LI-RADS (ICC, 0.68 vs 0.62, respectively; P = .03) and for dichotomized malignancy (ICC, 0.63 vs 0.53, respectively; P = .005), but not for LR-5 (P = .14) or LR-M (P = .94). Conclusion There was moderate agreement for LI-RADS version 2018 overall. For some comparisons, research-versus-research reader agreement was higher than research-versus-clinical reader agreement, indicating differences between the clinical and research environments that warrant further study. © RSNA, 2023 Supplemental material is available for this article. See also the editorials by Johnson and Galgano and Smith in this issue.

Simple Summary: In this study, the following injection characteristics were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model: (a) iron dose, (b) effect of dilution, (c) effect of injecting at different time courses and (d) effect of massaging the injection site. In conclusion, injection dose and time were primary factors for the SLN iron uptake. The result from this study will provide a background for magnetic procedures. The magnetic technique, consisting of a magnetic tracer and a handheld magnetometer, is a promising alternative technique for sentinel lymph node dissection (SLND) and was shown to be non-inferior to the standard technique in terms of identification rates. In this study, injection characteristics (iron dose, dilution, time course and massaging) were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model. 202 successful SLNDs were performed. Iron uptake in the SLN is proportional (10% utilization rate) to the injection dose between 20 and 200 μg, showing a plateau uptake of 80 μg in the SLN around 1000 μg injection. Linear regression showed that time had a higher impact than dilution, on the SLN iron uptake. Massaging showed no significant change in iron uptake. The amount of residual iron at the injection site was also proportional to the injection dose without any plateau. Time was a significant factor for wash-out of residual iron. From these results, preoperative injection may be advantageous for SLN detection as well as reduction in residual iron at the injection site by potential decrease in required injection dose. [ABSTRACT FROM AUTHOR]