What’s new in Genitourinary Imaging – February 2021

3 years ago


Arterial Spin Labeled Perfusion MRI for the Evaluation of Response to Tyrosine Kinase Inhibition Therapy in Metastatic Renal Cell Carcinoma

Tsai LL, Bhatt RS, Strob MF, Jegede OA, Sun MRM, Alsop DC, Catalano P, McDermott D, Robson PM, Atkins MB, Pedrosa I.

Radiology. 2020 Dec 1:201763. Epub ahead of print. PMID: 33258745.

doi: 10.1148/radiol.2020201763.


Background tumor perfusion may allow evaluation of tumor response to treatment. This group used Arterial Spin Labeled Perfusion (ASL) MRI to evaluate tumor response of metastatic renal cell carcinoma (RCC) after treatment with vascular endothelial growth factor (VEGFR) tyrosine kinase inhibitor. They prospectively evaluated 28 patients and determined the correlation between the ASL perfusion MRI and objective response rate (ORR) and progression-free survival (PFS). The group determined response by using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. A baseline study was obtained prior to treatment, as well as post treatment scans at 2 weeks, 12 weeks (2 cycles of treatment), and 24 weeks (4 cycles of treatment). They showed that responders had a higher baseline tumor perfusion than nonresponders. The reduction of perfusion was not associated with ORR or PFS.  In conclusion, the authors suggest that ASL MRI may play a role in the early detection of disease progression in metastatic RCC and assist in the detection of responders to VEGF inhibitors.


Intraplacental Fetal Vessel Diameter May Help Predict for Placental Invasiveness in Pregnant Women at High Risk for Placenta Accreta Spectrum Disorders

Bourgioti C, Konstantinidou AE, Zafeiropoulou K, Antoniou A, Fotopoulos S, Theodora M, Daskalakis G, Nikolaidou ME, Tzavara C, Letsika A, Martzoukos EA, Moulopoulos LA.

Radiology. 2020 Nov 24:200273. Epub ahead of print. PMID: 33231529.

doi: 10.1148/radiol.2020200273.


This group used placental MRI to identify the intraplacental vessel diameter (IFV) and to determine if there is an association with placenta accreta spectrum (PAS) disorder and peripartum complications. Two radiologists prospectively evaluated 160 women at a mean gestational age of 32 weeks. 81% were diagnosed with PAS, 54% of which had placenta percreta. At delivery, 24% of subjects experienced massive blood loss. IFVs were identified in 86% of patients with PAS, and in 98% of patients with placenta percreta. The relative risk ratio was 2.4 for PAS and 10 for percreta when IFVs were visible. IVFs greater than 2 mm were associated with PAS, and those greater than 3 mm were associated with placenta percreta and peripartum complications including massive bleeding (> 2000 mL). The authors suggest that the combination of IFVs with other MRI descriptors have improved ability to predict PAS with larger diameters (> 3 mm) predictive of placenta percreta and complications such massive blood loss.


Use of Intravenous Gadolinium-based Contrast Media in Patients with Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation

Weinreb JC, Rodby RA, Yee J, Wang CL, Fine D, McDonald RJ, Perazella MA, Dillman JR, Davenport MS.

Radiology. 2021 Jan;298(1):28-35. Epub 2020 Nov 10. PMID: 33170103.

doi: 10.1148/radiol.2020202903.


This article is a consensus statement between the ACR and National Kidney Foundation to evaluate the risk of nephrogenic systemic fibrosis (NSF) from various intravenous gadolinium-based agents. A multi-disciplinary group of 5 radiologists and 4 nephrologists evaluated the current literature and determined that the NSF risk from group II gadolinium-based contrast agents (GBCM) is low. A systematic review cited in the paper shows that none of the 4931 patients with GFR < 30 ml/min developed NSF. No unconfounded cases of NSF been have reported with group III GBCM. Additionally, the group also determined that dialysis initiation or alteration is unnecessary based on the administration of group II or III GBCMs.


Percutaneous Microwave Ablation of Category T1a Renal Cell Carcinoma: Intermediate Results on Safety, Technical Feasibility, and Clinical Outcomes of 119 Tumors

Guo J, Arellano RS.

AJR Am J Roentgenol. 2021 Jan;216(1):117-124. Epub 2020 Nov 19. PMID: 32603227.

doi: 10.2214/AJR.20.22818.


This group conducted a retrospective study to evaluate the safety, technical results, and the clinical outcomes of CT guided percutaneous microwave ablation of T1a RCC. 119 T1a RCCs were treated in 106 patients with technical success in 100% of the tumors and CR is 95.3% and PR in 4.7% of patients. Local progression free survival (PFS) and overall survival (OS) were 100.0% and 99.0% at 1 year, 92.8% and 97.7% at 2 years, and 90.6% and 94.6% at 3 years. Only 7 of patients had complications, which were categorized as SIR category A in 5 patients and 2 SIR category B in 2 patients. The group concludes that CT-guided percutaneous microwave ablation is a feasible alternative to treat T1a RCCs with its high rates of technical success, low complication rate, and excellent PFS and OS.


Preoperative prediction of the stage, size, grade, and necrosis score in clear cell renal cell carcinoma using MRI-based radiomics

Choi JW, Hu R, Zhao Y, Purkayastha S, Wu J, McGirr AJ, Stavropoulos SW, Silva AC, Soulen MC, Palmer MB, Zhang PJL, Zhu C, Ahn SH, Bai HX.

Abdom Radiol (NY). 2021 Jan 2. Epub ahead of print. PMID: 33386910.

doi: 10.1007/s00261-020-02876-x.


This group conducted a multi-center retrospective study on 364 patients with pathologically confirmed clear cell RCC. The group used a preoperative manually optimized MR radiomics model on T2 weighted and T1 post contrast imaging to predict the tumor stage, size, grade, and necrosis (SSIGN) score, which was compared to a machine learning pipeline, Tree-Based Pipeline Optimization Tool (TPOT). The group had a training set of 254 patients and a testing set of 110 patients. The MR radiomics model had an area under receiver operating characteristic curve (AUROC) of 0.89, area under precision-recall curve (AUPRC) of 0.81, accuracy of 0.89, specificity of 0.95, and sensitivity of 0.72, while TPOT had an area AUROC of 0.94, AUPRC of 0.83, accuracy of 0.89, specificity of 0.95, and sensitivity 0.72 on the test set.


Apparent diffusion coefficient values of cryptorchid testes and malignant transformation of cryptorchidism (MTC) (seminoma) in postpubertal patients

Liu R, Li J, Jiang Y, Wu Z, Chen Y, Li R.

Br J Radiol. 2021 Jan 7:20200624. Epub ahead of print. PMID: 33411594.

doi: 10.1259/bjr.20200624.


This group retrospectively reviewed the images of 35 patients with unilateral cryptorchidism. b0 and b800 DWI was obtained and mean ADC values were compared between normal testes, undescended testes, and malignant transformation of cryptorchidism (MTC). The mean ADC were as follows: normal 1.18 x 10-3, undescended 1.82 x 10-3, and MTC 0.80 x 10-3. The mean ADC were statistically different between normal and undescended or MTC. The calculated cut off values for differentiating normal and undescended (1.47 x 10-3) had sensitivity, specificity, and accuracy of 88%, 91%, and 90% respectively, while the cut off value for differentiation normal and MTC (1.22 x 10-3) had sensitivity, specificity, and accuracy 100%, 31%, and 43% respectively.  The authors conclude that ADC values is an additional tool that can be used in the clinical management of patients with cryptorchid testes.


Application of bi-planar reduced field-of-view DWI (rFOV DWI) in the assessment of muscle-invasiveness of bladder cancer

Meng X, Hu H, Wang Y, Hu D, Li Z, Feng C.

Eur J Radiol. 2020 Dec 31;136:109486. Epub ahead of print. PMID: 33434861.

doi: 10.1016/j.ejrad.2020.109486.


This retrospective study evaluated 61 patients who underwent axial full FOV DWI, axial rFOV DWI, and sagittal rFOV DWI. Image quality assessment, ADC values, and Vesical Imaging-Reporting and Data System (VI-RADS) scores were obtained and compared for the fFOV DWI and rFOV DWI. The CNR was higher for the rFOV DWI, while SNR was lower for fFOV DWI. The ADC value obtained from the muscle invasive bladder cancers were significantly lower than the non-muscle invasive bladder cancers for both the fFOV and rFOV. The subjective scores obtained from the rFOV compared to the fFOV were higher and bi-planar rFOV DWI had the highest predictive power for the determination of muscle invasive bladder cancer. The group suggests that biplanar rFOV DWI may provide more diagnostic confidence than single planar imaging for the presence of muscle invasive bladder cancer.

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