Radiogenomics of Intrahepatic Cholangiocarcinoma: Correlation of Imaging Features With BAP1 and FGFR Molecular Subtypes.

PURPOSE: Clinical research has shown unique tumor behavioral characteristics of BRCA-associated protein-1- (BAP1-) and fibroblast growth factor receptor (FGFR)-mutated intrahepatic cholangiocarcinomas (CCAs), with BAP1-mutated tumors demonstrating more aggressive forms of disease and FGFR-altered CCAs showing more indolent behavior. We performed a retrospective case-control study to evaluate for unique imaging features associated with BAP1 and FGFR genomic markers in intrahepatic CCA (iCCA). METHODS: Multiple imaging features of iCCA at first staging were analyzed by 2 abdominal radiologists blinded to genomic data. Growth and development of metastases at available follow-up imaging were also recorded, as were basic clinical cohort data. Types of iCCA analyzed included those with BAP1, FGFR, or both alterations, as well as cases with low mutational burden or mutations with low clinical impact, which served as a control or "wild-type" group. There were 18 cases in the FGFR group, 10 with BAP1 mutations, and 31 wild types (controls). RESULTS: Cases with BAP1 mutations showed significantly larger growth at first year of follow-up (P = 0.03) and more frequent tumor-associated biliary ductal dilatation (P = 0.04) compared with controls. FGFR-altered cases showed more infiltrative margins compared with controls (P = 0.047) and demonstrated less enhancement between arterial to portal venous phases (P = 0.02). BAP1 and FGFR groups had more cases with stage IV disease at presentation than controls (P = 0.025, P = 0.006). CONCLUSION: Compared with wild-type iCCAs, FGFR-mutated tumors often demonstrate infiltrative margins, and BAP1 tumors show increased biliary ductal dilatation at presentation. BAP1-mutated cases had significantly larger growth at first-year restaging.

Liver volumetry and liver-regenerative interventions: history, rationale, and emerging tools.

BACKGROUND: Postoperative hepatic insufficiency (PHI) is the most feared complication after hepatectomy. Volume of the future liver remnant (FLR) is one objectively measurable indicator to identify patients at risk of PHI. In this review, we summarized the development and rationale for the use of liver volumetry and liver-regenerative interventions and highlighted emerging tools that could yield new advancements in liver volumetry. METHODS: A review of MEDLINE/PubMed, Embase, and Cochrane Library databases was conducted to identify literature related to liver volumetry. The references of relevant articles were reviewed to identify additional publications. RESULTS: Liver volumetry based on radiologic imaging was developed in the 1980s to identify patients at risk of PHI and later used in the 1990s to evaluate grafts for living donor living transplantation. The field evolved in the 2000s by the introduction of standardized FLR based on the hepatic metabolic demands and in the 2010s by the introduction of the degree of hypertrophy and kinetic growth rate as measures of the FLR regenerative and functional capacity. Several liver-regenerative interventions, most notably portal vein embolization, are used to increase resectability and reduce the risk of PHI. In parallel with the increase in automation and machine assistance to physicians, many semi- and fully automated tools are being developed to facilitate liver volumetry. CONCLUSION: Liver volumetry is the most reliable tool to detect patients at risk of PHI. Advances in imaging analysis technologies, newly developed functional measures, and liver-regenerative interventions have been improving our ability to perform safe hepatectomy.

Impact of MRI/US fusion-guided prostate biopsy on biopsy-naïve patients: A single urologist's experience.

Objectives: To report our experience with imaging-guided targeted prostate biopsy (IGTpBx) for patients undergoing initial prostate biopsy in a clinical setting. Materials and methods: From July 2014 to February 2020, 305 men who had IGTpBx performed as their first prostate biopsy were enrolled. Two dedicated magnetic resonance imaging (MRI) radiologists segmented at least 1 region of interest (ROI) for each of these men using screening 1.5T MRI images. A single urologist employed the robotic-assisted Artemis MRI/ultrasonography (US) fusion platform to obtain 2-3 targeted samples from each ROI and additional random samples from the zones of the prostate outside the ROIs (a total of 12 zonal samples). Biopsy outcomes were categorized based on the Gleason score (GS) grade group (GG) as no cancer, favorable (GG < 3 or GS < 4 + 3), or clinically significant (GG ≥ 3 or GS ≥ 4 + 3) cancer. Results: The overall cancer detection rate was 75%:31% clinically significant, 44% favorable, and 25% no cancer. These findings triggered active interventions in 176 (58%) patients. A prostate-specific antigen (PSA) level of 0-4 ng/mL was detected in 39 (66%) of 59 patients (32 favorable, 7 significant), 4-10 ng/mL in 147 (77%) of 190 patients (85 favorable, 62 significant), and 10 ng/mL and over in 44 (80%) of 55 patients (17 favorable, 27 significant). Conclusions: The tumor detection rate was 75% with IGTpBx in patients without a previous biopsy. In addition, about 42% of detected cancers were deemed clinically significant and led to active interventions. IGTpBx as a patient's first prostate biopsy improves the detection of clinically significant prostate cancer when compared with historical data for random systematic prostate biopsy.

Arterial enhancement pattern predicts survival in patients with resectable and unresectable intrahepatic cholangiocarcinoma.

BACKGROUND: In patients undergoing resection of intrahepatic cholangiocarcinoma (ICC), hypervascularity during the arterial phase of contrast-enhanced computed tomography (CT) is associated with better prognosis than hypovascularity. However, the prognostic implications of arterial enhancement pattern in patients with unresectable ICC are unknown. We assessed the prognostic implications of arterial enhancement pattern in patients with resectable and unresectable ICC. METHODS: Consecutive patients who underwent surgery or gemcitabine-plus-cisplatin chemotherapy for ICC during 2003-2015 and CT with dynamic enhancement for diagnosis were included. After review by 2 radiologists, tumors were categorized according to the percentage of the tumor exhibiting arterial enhancement as hypervascular (>50% of tumor exhibiting enhancement), peripherally enhancing (10%-50%), and hypovascular (<10%). In each cohort (surgical and medical), overall survival (OS) curves were generated using the Kaplan-Meier method, and differences between curves were evaluated with Cox analysis. RESULTS: The study included 56 patients treated surgically and 89 patients with unresectable ICC. Mean (standard deviation) tumor density in the hypervascular, peripherally enhancing, and hypovascular groups was 119.3 (45.2) Hounsfield units (HU), 72.1 (15.9) HU, and 59.9 (14.4) HU, respectively, in the surgical cohort and 93.6 (17.5) HU, 66.6 (16.2) HU, and 48.7 (14.3) HU, respectively, in the medical cohort. In both cohorts, the 5-year OS rate was significantly higher in the hypervascular group than in the hypovascular group (surgical, 67.6% vs 22.5%, P = .038; medical, 15.4% vs 0%, P = .030). In both cohorts, a Cox proportional hazards model analysis showed that hypervascularity was significantly associated with better OS. CONCLUSION: Hypervascularity during the arterial CT phase is a prognostic biomarker in patients undergoing ICC resection and patients with unresectable ICC.

Tuberous Sclerosis Complex (TSC): Renal and Extrarenal Imaging.

Tuberous sclerosis complex is a multiorgan syndrome manifesting with several benign and malignant tumors. Complications arising from renal abnormalities are a leading cause of death in patients with tuberous sclerosis complex. Renal cell carcinoma is relatively uncommon, occurring in 2%-4% of patients with tuberous sclerosis complex syndrome, but nonetheless can significantly contribute to morbidity and mortality. Extrarenal manifestations of tuberous sclerosis complex, including within the chest, abdomen and central nervous system, aid in diagnosis. Pathogenesis and management are also discussed, including the importance of the types of renal masses found in these patients.

MRI Staging in an Evolving Management Paradigm for Rectal Cancer, From the AJR Special Series on Cancer Staging.

The treatment of rectal cancer centers around the distinct but related goals of management of distant metastases and management of local disease. Optimal local management requires attention to the primary tumor and its anatomic relationship to surrounding pelvic structures, with the goal of minimizing local recurrence (LR). High-resolution MRI is ideally suited for this purpose; application of MRI-based criteria in conjunction with optimized surgical and pathologic techniques has successfully reduced LR rates. This success has led to a shift away from using the TNM-based National Comprehensive Cancer Network (NCCN) guidelines as the sole determinant of whether a patient receives neoadjuvant chemoradiation. The new model uses a hybrid approach for assigning risk categories that combines elements of the TNM staging system with MRI-based anatomic features. These risk categories incorporate tumor proximity to the circumferential resection margin, T category, distance to the anal verge, and presence of extramural venous invasion to classify rectal tumors as low, intermediate, or high risk. This approach has been validated by accumulated data from numerous multiinstitutional studies. This article illustrates key anatomic concepts, depicts common interpretive errors and pitfalls, and discusses ongoing limitations; these insights should guide radiologists in optimal rectal MRI interpretation.

Accuracy of Prostate Magnetic Resonance Imaging: Reader Experience Matters.

BACKGROUND: Prostate magnetic resonance imaging (MRI) is increasingly used in the detection, image-guided biopsy, and active surveillance of prostate cancer. The accuracy of prostate MRI may differ based on factors including imaging technique, patient population, and reader experience. OBJECTIVE: To determine whether the accuracy of prostate MRI varies with reader experience. DESIGN SETTING AND PARTICIPANTS: We rescored regions of interest from 194 consecutive patients who had undergone MRI/ultrasonography fusion biopsy. Original prostate MRI scans had been interpreted by one of 33 abdominal radiologists (AR group). More than 14 mo later, rescoring was performed by two blinded, prostate MRI radiologists (PR group). Likert scoring was used for both original MRI reports and rescoring. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Test performance (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]) of prostate MRI was defined for the AR and PR groups. A Likert score of 4-5 was considered test positive and clinically significant prostate carcinoma (csPCa; Gleason grade group [GGG] ≥2) was considered outcome positive. RESULTS AND LIMITATIONS: MRI-positive lesions (Likert 4-5) scored by the PR group resulted in csPCa more frequently than those scored by the AR group (64.9% vs 39.3%). MRI-negative lesions (Likert 2-3) were more likely to result in a clinically insignificant biopsy (benign pathology or GGG 1) when scored by the PR versus the AR group (91.8% vs 76.6%). Sensitivity and specificity of MRI to detect csPCa were higher for the PR group than for the AR group (sensitivity 85.9% vs 70.7%; specificity 77.3% vs 46.8%). Overall diagnostic accuracy was higher for the PR group than for the AR group (80.1% vs 54.6%). CONCLUSIONS: Sensitivity, specificity, PPV, and NPV of prostate MRI were higher for the PR group than for the AR group. PATIENT SUMMARY: We examined the accuracy of prostate magnetic resonance imaging (MRI) in two groups of radiologists. Experienced radiologists were more likely to detect clinically significant prostate cancer on MRI.

Comparing confirmatory biopsy outcomes between MRI-targeted biopsy and standard systematic biopsy among men being enrolled in prostate cancer active surveillance.

OBJECTIVES: To evaluate the ability of magnetic resonance imaging (MRI)-targeted biopsy combined with systematic biopsy (MRI-biopsy) to reduce negative biopsies and detect clinically significant prostate cancer compared to systematic biopsy (SB) alone in the confirmatory biopsy setting using matched cohorts. PATIENTS AND METHODS: Patients were identified from an active surveillance database who had a previously positive transrectal ultrasonography-guided SB followed by a confirmatory biopsy at a single institution between 2006 and 2019. Patients were divided into two cohorts based on confirmatory biopsy technique: SB alone or MRI-biopsy (which included MRI-targeted and systematic biopsies). Cohorts were then matched on age, prostate-specific antigen (PSA) level, number of positive cores on initial biopsy and initial biopsy Gleason grade group (GG). Logistic regression was performed to identify associations with confirmatory biopsy upgrading. RESULTS: After matching, 514 patients were identified (257 per cohort). PSA, prostate volume and PSA density prior to initial biopsy, in addition to total number of initial biopsy positive cores and GG, were similar between the matched cohorts. After confirmatory biopsy, 118/257 patients (45.9%) in the MRI-biopsy cohort were upgraded compared to 46/257 patients (17.9%) in the SB cohort (P < 0.001). The rate of negative confirmatory biopsy was 32/257 (12.5%) compared to 97/257 (37.7%) in the MRI-biopsy and SB cohorts, respectively (P < 0.001). Confirmatory MRI-biopsy was associated with greater odds of confirmatory biopsy upgrade from GG 1 to ≥GG 2 compared to SB alone (odds ratio 3.62, 95% confidence interval 1.97-6.63; P < 0.001). CONCLUSION: The addition of MRI-targeted biopsies to SB in the confirmatory biopsy setting among men with previously detected prostate cancer resulted in fewer negative confirmatory biopsies and detection of more clinically significant prostate cancer compared to SB alone.

Comparison of virtual to true unenhanced abdominal computed tomography images acquired using rapid kV-switching dual energy imaging.

OBJECTIVE: To compare "virtual" unenhanced (VUE) computed tomography (CT) images, reconstructed from rapid kVp-switching dual-energy computed tomography (DECT), to "true" unenhanced CT images (TUE), in clinical abdominal imaging. The ability to replace TUE with VUE images would have many clinical and operational advantages. METHODS: VUE and TUE images of 60 DECT datasets acquired for standard-of-care CT of pancreatic cancer were retrospectively reviewed and compared, both quantitatively and qualitatively. Comparisons included quantitative evaluation of CT numbers (Hounsfield Units, HU) measured in 8 different tissues, and 6 qualitative image characteristics relevant to abdominal imaging, rated by 3 experienced radiologists. The observed quantitative and qualitative VUE and TUE differences were compared against boundaries of clinically relevant equivalent thresholds to assess their equivalency, using modified paired t-tests and Bayesian hierarchical modeling. RESULTS: Quantitatively, in tissues containing high concentrations of calcium or iodine, CT numbers measured in VUE images were significantly different from those in TUE images. CT numbers in VUE images were significantly lower than TUE images when calcium was present (e.g. in the spine, 73.1 HU lower, p < 0.0001); and significantly higher when iodine was present (e.g. in renal cortex, 12.9 HU higher, p < 0.0001). Qualitatively, VUE image ratings showed significantly inferior depiction of liver parenchyma compared to TUE images, and significantly more cortico-medullary differentiation in the kidney. CONCLUSIONS: Significant differences in VUE images compared to TUE images may limit their application and ability to replace TUE images in diagnostic abdominal CT imaging.

Tumor response criteria for assessing pazopanib first-line therapy in patients with metastatic renal cell carcinoma (mRCC).

PURPOSE: To identify the optimum response criteria for first-line targeted pazopanib therapy in patients with mRCC using solid tumor response criteria and clinical risk factors. METHODS: Pre- and post-treatment CTs of patients (n = 43) with mRCC treated with first-line pazopanib therapy were analyzed retrospectively. Treatment response was evaluated with Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, Choi, modified Choi (mChoi), revised Choi (rChoi), MASS (Morphology, Attenuation, Size, and Structure), 10% threshold criteria, and subjective assessment. Memorial Sloan-Kettering Cancer Center and International Metastatic Renal Cell Carcinoma Database Consortium clinical risk factors were also used to define response groups. Response evaluations were correlated with overall survival (OS) and progression-free survival (PFS) using log-rank test. RESULTS: Patients with partial response (PR) by mChoi and rChoi had longer OS than those with stable disease (SD) (P < 0.001). Responders by 10% threshold criteria also had better OS, without or combined with clinical criteria. Patients with PR by rChoi, mChoi, RECIST v1.1, MASS criteria, and by subjective assessment had longer PFS than those with SD. rChoi and mChoi criteria best delineated the difference in PFS for patients with PR versus SD, without or combined with clinical criteria. CONCLUSION: For mRCC patients treated with pazopanib, OS and PFS for PR and SD groups were best predicted by rChoi and mChoi criteria, without or combined with clinical risk factors. 10% threshold criteria also predicted OS and PFS, whereas RECIST did so only in a limited number of patients.

Tumor thrombus in the venous drainage pathways of primary, recurrent and metastatic disease on routine oncologic imaging studies: beyond hepatocellular and renal cell carcinomas.

Radiologists routinely evaluate for tumor thrombus in the portal and hepatic veins in patients with hepatocellular carcinoma and in the renal vein and inferior vena cava in patients with renal cell carcinoma. However, tumor thrombus occurs in association with numerous other tumor types, e.g. colorectal carcinoma and pancreatic neuroendocrine tumor. Furthermore tumor thrombi are not limited to the primary tumor but also seen with local recurrence and metastatic disease. While less recognized, these thrombi nevertheless affect patterns of recurrence and prognosis. Their detection is critical for accurate local staging and early detection of local recurrence and metastatic disease. The purpose of this pictorial review is to draw the attention of radiologists to the less familiar manifestations of tumor thrombus, review the imaging findings and illustrate the clinical significance of these thrombi.

Intrahepatic Recurrence Patterns Predict Survival After Resection of Colorectal Liver Metastases.

BACKGROUND: After resection of colorectal liver metastases (CLM), up to 40% of patients will develop intrahepatic recurrence. This study aims to identify patterns of intrahepatic recurrence and their impact on survival after preoperative chemotherapy and CLM resection. METHODS: A retrospective review was performed of patients developing intrahepatic recurrence after CLM resection following preoperative chemotherapy. Prechemotherapy, preoperative, and postoperative computed tomography scans were reviewed. Recurrences were classified as in situ, de novo, or both in situ and de novo. Median follow-up was 42 months (range 2-144 months). RESULTS: Among 223 patients meeting study criteria, intrahepatic recurrence was identified a median of 9 months after hepatectomy. Isolated de novo or in situ recurrence developed in 105 (47%) and 86 (39%) patients, respectively. Thirty-two patients (14%) developed both in situ and de novo recurrence, which was associated with significantly lower median overall survival of 33 months compared with 49 and 45 months with isolated in situ or de novo recurrence, respectively (p = 0.048). Among 118 patients (53%) who developed in situ recurrence as a component of disease relapse, recurrences resulted from disappearing or missed liver metastases in 47 patients (40%). CONCLUSIONS: An intrahepatic recurrence pattern of both in situ and de novo metastases after CLM resection following preoperative chemotherapy predicts significantly worse overall survival compared with isolated in situ or de novo recurrence.

Consultation and citation rates for prior imaging studies and documents in radiology.

Frequently, the consensus conclusion after quality assurance conferences in radiology is that whatever mistake was made could have been avoided if more prior images or documents had been consulted. It is generally assumed that anything that was not specifically cited in the report had not been consulted. Is it actually safe to assume that an image or document that is not cited was also not consulted? It is this question that this investigation addresses. In this Institutional Review Board-approved study, one observer watched the board-certified radiologists while they interpreted imaging studies and issued reports. He recorded what type of study was being interpreted [either computed tomography, magnetic resonance imaging, or conventional radiography (x-ray)]. He also recorded the number and type of prior imaging studies and documents that were consulted during the interpretation. These observations were then compared with the signed report to determine how many of the consulted imaging studies and documents were cited. Of the 198 previous imaging studies that the radiologists consulted, 116 (58.6%) were cited in a report. Of the 285 documents consulted, 3 (1.1%) were cited in a report. This difference in citation rate was statistically significant ([Formula: see text]). It cannot be safely assumed that an older radiologic image or medical document was not consulted during radiologic interpretation merely because it is not cited in the report. Radiologists often consult more old studies than they cite, and they do not cite the majority of prior documents that they consult.

Lynch Syndrome: Genomics Update and Imaging Review.

Lynch syndrome is the most common hereditary cancer syndrome, the most common cause of heritable colorectal cancer, and the only known heritable cause of endometrial cancer. Other cancers associated with Lynch syndrome include cancers of the ovary, stomach, urothelial tract, and small bowel, and less frequently, cancers of the brain, biliary tract, pancreas, and prostate. The oncogenic tendency of Lynch syndrome stems from a set of genomic alterations of mismatch repair proteins. Defunct mismatch repair proteins cause unusually high instability of regions of the genome called microsatellites. Over time, the accumulation of mutations in microsatellites and elsewhere in the genome can affect the production of important cellular proteins, spurring tumorigenesis. Universal testing of colorectal tumors for microsatellite instability (MSI) is now recommended to (a) prevent cases of Lynch syndrome being missed owing to the use of clinical criteria alone, (b) reduce morbidity and mortality among the relatives of affected individuals, and (c) guide management decisions. Organ-specific cancer risks and associated screening paradigms vary according to the sex of the affected individual and the type of germline DNA alteration causing the MSI. Furthermore, Lynch syndrome-associated cancers have different pathologic, radiologic, and clinical features compared with their sporadic counterparts. Most notably, Lynch syndrome-associated tumors tend to be more indolent than non-Lynch syndrome-associated neoplasms and thus may respond differently to traditional chemotherapy regimens. The high MSI in cases of colorectal cancer reflects a difference in the biologic features of the tumor, possibly with a unique susceptibility to immunotherapy. ©RSNA, 2018.

Alternative Response Criteria and Clinical Risk Factors for Assessing Tumor Response in Patients With Metastatic Renal Cell Carcinoma Who Are Receiving Salvage Therapy.

OBJECTIVE: The purpose of this study is to compare the prognostic value of various solid tumor response criteria as well as the additive value of clinical risk factors in patients with advanced renal cell carcinoma (RCC). MATERIALS AND METHODS: Two sets of CT scans (pretreatment scans and scans obtained 1-3.5 months after treatment) were reviewed for 57 patients with metastatic RCC treated with pazopanib in the salvage setting. Tumor response on the posttherapy scan was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) and Choi, modified Choi (mChoi), MASS (Morphology, Attenuation, Size, and Structure), and 10% threshold criteria. In addition, combined Memorial Sloan-Kettering Cancer Center (MSKCC) risk factors plus imaging criteria were used to define response groups. Response evaluations using these criteria were correlated with overall survival (OS) and progression-free survival (PFS), with use of the log-rank test. RESULTS: Patients classified as having progressive disease (PD) on the basis of RECIST, mChoi, and MASS criteria had a significantly worse OS than patients with stable disease (SD) and partial response (PR). With the addition of MSKCC risk factors, all groups with PD defined by combined criteria had significantly worse OS. For 37 patients with no or one MSKCC risk factor, response groups defined by Choi, mChoi, MASS, and 10% threshold criteria did not differ in PFS or OS. However, among 20 patients with two to three MSKCC risk factors, those classified as having PR had longer PFS than did those with SD and had longer OS than did those with PD. CONCLUSION: For patients with advanced RCC for which prior therapies have failed, the prognostic value of various imaging-based tumor response criteria differs on the basis of the MSKCC clinical risk status.

The ABCs of BHD: An In-Depth Review of Birt-Hogg-Dubé Syndrome.

OBJECTIVE: Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant inherited syndrome involving multiple organs. In young patients, renal neoplasms that are multiple, bilateral, or both, such as oncocytomas, chromophobe renal cell carcinoma (RCC), hybrid chromophobe RCC-oncocytomas, clear cell RCC, and papillary RCC, can suggest BHD syndrome. Extrarenal findings, including dermal lesions, pulmonary cysts, and spontaneous pneumothoraces, also aid in diagnosis. CONCLUSION: Radiologists may be one of the first medical specialists to suggest the diagnosis of BHD syndrome. Knowledge of pathogenesis and management, including the importance of the types of renal neoplasms in a given patient, is needed to properly recognize this rare condition.

Imaging features of rare mesenychmal liver tumours: beyond haemangiomas.

Tumours arising from mesenchymal tissue components such as vascular, fibrous and adipose tissue can manifest in the liver. Although histopathology is often necessary for definitive diagnosis, many of these lesions exhibit characteristic imaging features. The radiologist plays an important role in suggesting the diagnosis, which can direct appropriate immunohistochemical staining at histology. The aim of this review is to present clinical and imaging findings of a spectrum of mesenchymal liver tumours such as haemangioma, epithelioid haemangioendothelioma, lipoma, PEComa, angiosarcoma, inflammatory myofibroblastic tumour, solitary fibrous tumour, leiomyoma, leiomyosarcoma, Kaposi sarcoma, mesenchymal hamartoma, undifferentiated embryonal sarcoma, rhabdomyosarcoma and hepatic metastases. Knowledge of the characteristic features of these tumours will aid in guiding the radiologic diagnosis and appropriate patient management.

Comparative Effectiveness of Tumor Response Assessment Methods: Standard of Care Versus Computer-Assisted Response Evaluation.

PURPOSE: To compare the effectiveness of metastatic tumor response evaluation with computed tomography using computer-assisted versus manual methods. MATERIALS AND METHODS: In this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study, 11 readers from 10 different institutions independently categorized tumor response according to three different therapeutic response criteria by using paired baseline and initial post-therapy computed tomography studies from 20 randomly selected patients with metastatic renal cell carcinoma who were treated with sunitinib as part of a completed phase III multi-institutional study. Images were evaluated with a manual tumor response evaluation method (standard of care) and with computer-assisted response evaluation (CARE) that included stepwise guidance, interactive error identification and correction methods, automated tumor metric extraction, calculations, response categorization, and data and image archiving. A crossover design, patient randomization, and 2-week washout period were used to reduce recall bias. Comparative effectiveness metrics included error rate and mean patient evaluation time. RESULTS: The standard-of-care method, on average, was associated with one or more errors in 30.5% (6.1 of 20) of patients, whereas CARE had a 0.0% (0.0 of 20) error rate ( P < .001). The most common errors were related to data transfer and arithmetic calculation. In patients with errors, the median number of error types was 1 (range, 1 to 3). Mean patient evaluation time with CARE was twice as fast as the standard-of-care method (6.4 minutes v 13.1 minutes; P < .001). CONCLUSION: CARE reduced errors and time of evaluation, which indicated better overall effectiveness than manual tumor response evaluation methods that are the current standard of care.