Contemporary and Emerging MRI Strategies for Assessing Kidney Allograft Complications: Arterial Stenosis and Parenchymal Injury, From the AJR Special Series on Imaging of Fibrosis.

MRI plays an important role in the evaluation of kidney allografts for vascular complications as well as parenchymal insults. Transplant renal artery stenosis, the most common vascular complication of kidney transplant, can be evaluated by MRA using gadolinium and nongadolinium contrast agents as well as by unenhanced MRA techniques. Parenchymal injury occurs through a variety of pathways, including graft rejection, acute tubular injury, BK polyomavirus infection, drug-induced interstitial nephritis, and pyelonephritis. Investigational MRI techniques have sought to differentiate among these causes of dysfunction as well as to assess the degree of interstitial fibrosis or tubular atrophy (IFTA)-the common end pathway for all of these processes-which is currently evaluated by invasively obtained core biopsies. Some of these MRI sequences have shown promise in not only assessing the cause of parenchymal injury but also assessing IFTA noninvasively. This review describes current clinically used MRI techniques and previews promising investigational MRI techniques for assessing complications of kidney grafts.

A Multicenter Assessment of Interreader Reliability of LI-RADS Version 2018 for MRI and CT.

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.

Hepatocellular carcinoma surveillance, incidence, and tumor doubling times in patients cured of hepatitis C.

BACKGROUND: Hepatocellular carcinoma (HCC) incidence and mortality vary by race/ethnicity and both are higher in Black patients than in Whites. For HCC surveillance, all cirrhotic patients are advised to undergo lifelong twice-annual abdominal imaging. We investigated factors associated with surveillance and HCC incidence in a diverse HCC risk group, cirrhotic patients recently cured of hepatitis C virus (HCV) infection. METHODS: In this observational cohort study, all participants (n = 357) had advanced fibrosis/cirrhosis and were cured of HCV with antiviral treatment. None had Liver Imaging Reporting and Data System (LI-RADS) 2-5 lesions prior to HCV cure. Ultrasound, computed tomography, and/or magnetic resonance imaging were used for surveillance. RESULTS: At a median follow-up of 40 months [interquartile range (IQR) = 28-48], the median percentage of time up-to-date with surveillance was 49% (IQR) = 30%-71%. The likelihood of receiving a first surveillance examination was not significantly associated with race/ethnicity, but was higher for patients with more advanced cirrhosis, for example, bilirubin [odds ratio (OR) = 3.8/mg/dL, p = 0.002], private insurance (OR = 3.4, p = 0.006), and women (OR = 2.3, p = 0.008). The likelihood of receiving two or three examinations was significantly lower for non-Hispanic Blacks and Hispanics versus non-Hispanic Whites (OR = 0.39, and OR = 0.40, respectively, p < 0.005 for both) and for patients with higher platelet counts (OR = 0.99/10,000 cells/µl, p = 0.01), but higher for patients with private insurance (OR = 2.8, p < 0.001). Incident HCC was associated with higher bilirubin (OR = 1.7, p = 0.02) and lower lymphocyte counts (OR = 0.16, p = 0.01). CONCLUSIONS: Contrary to best practices, HCC surveillance was associated with sociodemographic factors (insurance status and race/ethnicity) among patients cured of HCV. Guideline-concordant surveillance is needed to address healthcare disparities.

CT/MRI and CEUS LI-RADS Major Features Association with Hepatocellular Carcinoma: Individual Patient Data Meta-Analysis.

Background The Liver Imaging Reporting and Data System (LI-RADS) assigns a risk category for hepatocellular carcinoma (HCC) to imaging observations. Establishing the contributions of major features can inform the diagnostic algorithm. Purpose To perform a systematic review and individual patient data meta-analysis to establish the probability of HCC for each LI-RADS major feature using CT/MRI and contrast-enhanced US (CEUS) LI-RADS in patients at high risk for HCC. Materials and Methods Multiple databases (MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus) were searched for studies from January 2014 to September 2019 that evaluated the accuracy of CT, MRI, and CEUS for HCC detection using LI-RADS (CT/MRI LI-RADS, versions 2014, 2017, and 2018; CEUS LI-RADS, versions 2016 and 2017). Data were centralized. Clustering was addressed at the study and patient levels using mixed models. Adjusted odds ratios (ORs) with 95% CIs were determined for each major feature using multivariable stepwise logistic regression. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) (PROSPERO protocol: CRD42020164486). Results A total of 32 studies were included, with 1170 CT observations, 3341 MRI observations, and 853 CEUS observations. At multivariable analysis of CT/MRI LI-RADS, all major features were associated with HCC, except threshold growth (OR, 1.6; 95% CI: 0.7, 3.6; P = .07). Nonperipheral washout (OR, 13.2; 95% CI: 9.0, 19.2; P = .01) and nonrim arterial phase hyperenhancement (APHE) (OR, 10.3; 95% CI: 6.7, 15.6; P = .01) had stronger associations with HCC than enhancing capsule (OR, 2.4; 95% CI: 1.7, 3.5; P = .03). On CEUS images, APHE (OR, 7.3; 95% CI: 4.6, 11.5; P = .01), late and mild washout (OR, 4.1; 95% CI: 2.6, 6.6; P = .01), and size of at least 20 mm (OR, 1.6; 95% CI: 1.04, 2.5; P = .04) were associated with HCC. Twenty-five studies (78%) had high risk of bias due to reporting ambiguity or study design flaws. Conclusion Most Liver Imaging Reporting and Data System major features had different independent associations with hepatocellular carcinoma; for CT/MRI, arterial phase hyperenhancement and washout had the strongest associations, whereas threshold growth had no association. © RSNA, 2021 Online supplemental material is available for this article.

Assessing locoregional treatment response to Hepatocellular Carcinoma: comparison of hepatobiliary contrast agents to extracellular contrast agents.

Cross-sectional imaging with contrast-enhanced magnetic resonance imaging (MRI) is routinely performed in patients with hepatocellular carcinoma (HCC) to assess tumor response to locoregional therapy (LRT). Current response assessment algorithms, such as the Liver Imaging Reporting and Data System (LI-RADS) treatment response algorithm (TRA), allow assessment using conventional gadolinium-based extracellular contrast agents (ECA) for accurate tumor response assessment following LRT. MRI with hepatobiliary agents (HBA) allows an acquisition of hepatobiliary phase (HBP), which is proven to increase sensitivity for detection of observations in at-risk patients, particularly for findings < 2 cm. The use of HBA is not yet incorporated into the TRA; however, it is increasingly used in clinical practice. Few published studies have evaluated the performance of LI-RADS TRA by applying ancillary features related to HBP that has resulted in category adjustment, enabling more sensitive and unequivocal diagnosis. This may help timely management of viable cases, without a significant loss of specificity in comparison with the ECA-based LI-RADS TRA assessment. In this review, we will describe and compare the imaging appearance of treated HCC on MRI using extracellular and hepatobiliary contrast agents and discuss emerging evidence and pitfalls in the assessment of tumor response following LRT with HBA.

MR defecography review.

Pelvic floor dysfunction is a relatively common but often complex condition, presenting with a variety of clinical symptoms, especially when it involves multiple compartments. Clinical exam alone is often inadequate and requires a complementary imaging study. Magnetic resonance defecography (MRD) is an excellent noninvasive diagnostic study with its multiplanar capability, lack of ionizing radiation and excellent soft tissue resolution. It can identify both anatomic and functional abnormalities in the pelvic floor and specifically excels in its ability to simultaneously detect multicompartmental pathology and help with vital pre-operative assessment. This manuscript reviews the relevant anatomical landmarks, describes the optimal technique, highlights an approach to the interpretation of MRD, and provides an overview of the various pelvic floor disorders in the different anatomical compartments.

Transperineal Versus Transrectal Targeted Biopsy With Use of Electromagnetically-tracked MR/US Fusion Guidance Platform for the Detection of Clinically Significant Prostate Cancer.

OBJECTIVE: To compare transperineal (TP-TBx) and transrectal (TR-TBx) targeted prostate biopsy in a prospective non randomized single surgeon series of MR/US fusion-guided targeted biopsy performed using an electromagnetic tracking platform (NCT04026763). MATERIALS AND METHODS: In this single-institution prospective study, 168 patients who underwent transperineal systematic 12-core biopsy and TP-TBx with electromagnetic tracking (UroNav, Invivo, Gainesville, FL) were compared to 211 patients who underwent a similar procedure by a transrectal approach. Univariate and multivariate analyses were used to assess if biopsy technique impacted all cancer detection rates or clinically significant (Gleason score >3+4) cancer detection rates. RESULTS: Patients who underwent TP-TBx were older (68 vs 65 y, P = .014), with a slightly higher rate of PI-RADSv2.0 score (39% vs 28%, P = .039) and higher lesion volume on mpMRI (0.54 vs 0.41 cc, P = .039). The rates of CS disease detection by TP-TBx and TR-TBx were 59% and 54%, respectively. In a multivariate analysis adjusting for PSA, previous biopsy status, prostate volume, PI-RADS score, lesion volume, and lesion location, there was no statistically significant difference in likelihood to detect any PCa (OR, 0.98; 95% CI, 0.56-1.71; P = .940) or CS PCa (OR, 0.94, 95% CI, 0.58-1.51; P = .791). CONCLUSION: Transperineal targeted biopsy with electromagnetic-tracking is comparable to the transrectal fusion-guided approach in the detection of any PCa and csPCa cancer.

A cohort of transperineal electromagnetically tracked magnetic resonance imaging/ultrasonography fusion-guided biopsy: assessing the impact of inter-reader variability on cancer detection.

OBJECTIVE: To evaluate the ability to detect clinically significant prostate cancer (PCa) using a novel electromagnetically (EM) tracked transperineal magnetic resonance imaging (MRI)/ultrasonography (US) fusion-guided targeted biopsy (transperineal TBx) platform and the impact of inter-reader variability on cancer detection. MATERIALS AND METHODS: A total of 176 patients with suspicious lesions detected on multiparametric MRI (mpMRI) underwent a systematic modified Barzel template biopsy (12-core) transperineal biopsy (transperineal SBx) and transperineal TBx with EM tracking (UroNav; Philips Healthcare, Best, the Netherlands) in the same setting. Cancer detection rates (CDRs) were stratified by Prostate Imaging Reporting and Data System (PI-RADS) v2 scores and compared with Fisher's exact test. Area under the curve (AUC) was calculated for prostate-specific antigen (PSA), PSA density (PSAD), PI-RADS score, and subgroup analysis of individual readers' PI-RADS scores with respect to overall CDR and clinically significant CDR. RESULTS: The overall CDR was 76.7% (135/176), of which 76.3% (103/135) was clinically significant PCa. Among the 135 patients with PCa, transperineal TBx detected 90.4% of cases (122/135), either alone or in combination with transperineal SBx. The remaining 9.6% of cases (13/135) missed by transperineal TBx were diagnosed by transperineal SBx alone, of which three were clinically significant. Conversely, transperineal SBx missed 14% of cases (19/135), 14 of which were clinically significant PCa. Sensitivities for transperineal TBx and transperineal SBx were 90.4% and 85.9%, respectively. On a per-lesion basis, PI-RADS score (AUC 0.74) outperformed both PSA (AUC 0.59) and PSAD (AUC 0.63) in discriminating clinically significant from non-clinically significant PCa on transperineal TBx. Although not formally statistically tested, AUCs amongst different mpMRI readers appeared to display considerable variability. There were no adverse events, including sepsis. CONCLUSIONS: Electromagnetically tracked transperineal TBx of MRI-visible lesions enhanced the ability of transperineal SBx to detect PCa, with greater sensitivity for clinically significant disease. These findings suggest transperineal TBx is a safe, alternative fusion platform for patients with a suspicious lesion on prostate MRI. The assessment of inter-reader variability, in conjunction with prediction of clinically significant PCa and CDR, is an important first step for quality control in implementing an MRI-based screening programme.

Gold nanoshell-localized photothermal ablation of prostate tumors in a clinical pilot device study.

Biocompatible gold nanoparticles designed to absorb light at wavelengths of high tissue transparency have been of particular interest for biomedical applications. The ability of such nanoparticles to convert absorbed near-infrared light to heat and induce highly localized hyperthermia has been shown to be highly effective for photothermal cancer therapy, resulting in cell death and tumor remission in a multitude of preclinical animal models. Here we report the initial results of a clinical trial in which laser-excited gold-silica nanoshells (GSNs) were used in combination with magnetic resonance-ultrasound fusion imaging to focally ablate low-intermediate-grade tumors within the prostate. The overall goal is to provide highly localized regional control of prostate cancer that also results in greatly reduced patient morbidity and improved functional outcomes. This pilot device study reports feasibility and safety data from 16 cases of patients diagnosed with low- or intermediate-risk localized prostate cancer. After GSN infusion and high-precision laser ablation, patients underwent multiparametric MRI of the prostate at 48 to 72 h, followed by postprocedure mpMRI/ultrasound targeted fusion biopsies at 3 and 12 mo, as well as a standard 12-core systematic biopsy at 12 mo. GSN-mediated focal laser ablation was successfully achieved in 94% (15/16) of patients, with no significant difference in International Prostate Symptom Score or Sexual Health Inventory for Men observed after treatment. This treatment protocol appears to be feasible and safe in men with low- or intermediate-risk localized prostate cancer without serious complications or deleterious changes in genitourinary function.

Novel nomogram for the prediction of seminal vesicle invasion including multiparametric magnetic resonance imaging.

OBJECTIVES: To create a model that predicts side-specific seminal vesicle invasion using clinical, biopsy and multiparametric magnetic resonance imaging data. METHODS: We analyzed data from 544 patients who underwent robot-assisted radical prostatectomy at a single institution. To develop a side-specific predictive model, we ultimately considered four variables: prostate-specific antigen, highest ipsilateral biopsy Gleason grade, highest ipsilateral percentage core involvement and seminal vesicle invasion on multiparametric magnetic resonance imaging. A binary multivariable logistic regression model was fitted to predict seminal vesicle invasion. A nomogram was then built based on the coefficients of the resulting logit function. The leave-one-out cross validation method was used for internal validation, and the decision curve analysis for the evaluation of the net clinical benefit. RESULTS: We relied on 804 side-specific cases after excluding negative biopsy observations (n = 284). Seminal vesicle invasion was reported on multiparametric magnetic resonance imaging in 41 (5%) cases, and on final pathology in 64 (8%) cases. All variables in the model emerged as predictors of seminal vesicle invasion (all P ≤ 0.001) and were subsequently considered to build a nomogram. The area under the curve of multiparametric magnetic resonance imaging alone in predicting seminal vesicle invasion was 59.1%; whereas one of the clinical variables only was 85.1%. The area under the curve of the nomogram resulting from their combination was 86.5%. After internal validation, this resulted in 84.7%. The model achieved good calibration and the decision curve analysis showed its clinical benefit, especially when compared with relying only on multiparametric magnetic resonance imaging prediction of seminal vesicle invasion. CONCLUSIONS: A nomogram based on clinical and multiparametric magnetic resonance imaging data can predict seminal vesicle invasion and serve as a tool to urologists for surgical planning.

Development and internal validation of a side-specific, multiparametric magnetic resonance imaging-based nomogram for the prediction of extracapsular extension of prostate cancer.

OBJECTIVES: To develop a nomogram for predicting side-specific extracapsular extension (ECE) for planning nerve-sparing radical prostatectomy. MATERIALS AND METHODS: We retrospectively analysed data from 561 patients who underwent robot-assisted radical prostatectomy between February 2014 and October 2015. To develop a side-specific predictive model, we considered the prostatic lobes separately. Four variables were included: prostate-specific antigen; highest ipsilateral biopsy Gleason grade; highest ipsilateral percentage core involvement; and ECE on multiparametric magnetic resonance imaging (mpMRI). A multivariable logistic regression analysis was fitted to predict side-specific ECE. A nomogram was built based on the coefficients of the logit function. Internal validation was performed using 'leave-one-out' cross-validation. Calibration was graphically investigated. The decision curve analysis was used to evaluate the net clinical benefit. RESULTS: The study population consisted of 829 side-specific cases, after excluding negative biopsy observations (n = 293). ECE was reported on mpMRI and final pathology in 115 (14%) and 142 (17.1%) cases, respectively. Among these, mpMRI was able to predict ECE correctly in 57 (40.1%) cases. All variables in the model except highest percentage core involvement were predictors of ECE (all P ≤ 0.006). All variables were considered for inclusion in the nomogram. After internal validation, the area under the curve was 82.11%. The model demonstrated excellent calibration and improved clinical risk prediction, especially when compared with relying on mpMRI prediction of ECE alone. When retrospectively applying the nomogram-derived probability, using a 20% threshold for performing nerve-sparing, nine out of 14 positive surgical margins (PSMs) at the site of ECE resulted above the threshold. CONCLUSION: We developed an easy-to-use model for the prediction of side-specific ECE, and hope it serves as a tool for planning nerve-sparing radical prostatectomy and in the reduction of PSM in future series.

Patient-directed Internet-based Medical Image Exchange: Experience from an Initial Multicenter Implementation.

RATIONALE AND OBJECTIVES: Inefficient transfer of personal health records among providers negatively impacts quality of health care and increases cost. This multicenter study evaluates the implementation of the first Internet-based image-sharing system that gives patients ownership and control of their imaging exams, including assessment of patient satisfaction. MATERIALS AND METHODS: Patients receiving any medical imaging exams in four academic centers were eligible to have images uploaded into an online, Internet-based personal health record. Satisfaction surveys were provided during recruitment with questions on ease of use, privacy and security, and timeliness of access to images. Responses were rated on a five-point scale and compared using logistic regression and McNemar's test. RESULTS: A total of 2562 patients enrolled from July 2012 to August 2013. The median number of imaging exams uploaded per patient was 5. Most commonly, exams were plain X-rays (34.7%), computed tomography (25.7%), and magnetic resonance imaging (16.1%). Of 502 (19.6%) patient surveys returned, 448 indicated the method of image sharing (Internet, compact discs [CDs], both, other). Nearly all patients (96.5%) responded favorably to having direct access to images, and 78% reported viewing their medical images independently. There was no difference between Internet and CD users in satisfaction with privacy and security and timeliness of access to medical images. A greater percentage of Internet users compared to CD users reported access without difficulty (88.3% vs. 77.5%, P < 0.0001). CONCLUSION: A patient-directed, interoperable, Internet-based image-sharing system is feasible and surpasses the use of CDs with respect to accessibility of imaging exams while generating similar satisfaction with respect to privacy.

Telangiectatic hyperplastic nodule associated with vascular malformation in a patient with chronic hepatitis B: radiologic and pathologic features.

Recognizing hepatocellular nodules that cannot be classified as typical for hepatocellular carcinoma, hepatocellular adenoma, or focal nodular hyperplasia is important, especially in a patient with high risk for hepatocellular carcinoma. The authors report a case of a 53-year-old man with chronic hepatitis B, who was referred to the hospital with a liver mass found on routine imaging follow-up. Abdominal ultrasound revealed a 2.4-cm hypoechoic lesion. Contrast computed tomography showed homogeneous arterial enhancement and mild hyperdensity on portal venous phase images. Due to the high risk for hepatocellular carcinoma, the patient underwent laparoscopic left lateral segmentectomy that revealed a 2.2-cm poorly defined red-brown lesion. The nodule was diagnosed as a hypervascular/telangiectatic hyperplastic hepatocellular nodule based on histopathologic findings and immunostaining profile with negative glutamine synthetase, diffuse positive CD34 highlighting hyperplastic endothelial cells along the telangiectatic sinusoids and dilated vascular channels, and CK7 and CK19 reactive normal bile ducts within the lesion.