Uday Patel

Magnetic Resonance Imaging–Detected Tumor Response for Locally Advanced Rectal Cancer Predicts Survival Outcomes: MERCURY Experience

PURPOSE To assess magnetic resonance imaging (MRI) and pathologic staging after neoadjuvant therapy for rectal cancer in a prospectively enrolled, multicenter study. METHODS In a prospective cohort study, 111 patients who had rectal cancer treated by neoadjuvant therapy were assessed for response by MRI and pathology staging by T, N and circumferential resection margin (CRM) status. Tumor regression grade (TRG) was also assessed by MRI. Overall survival (OS) was estimated by using the Kaplan-Meier product-limit method, and Cox proportional hazards models were used to determine associations between staging of good and poor responders on MRI or pathology and survival outcomes after controlling for patient characteristics. RESULTS On multivariate analysis, the MRI-assessed TRG (mrTRG) hazard ratios (HRs) were independently significant for survival (HR, 4.40; 95% CI, 1.65 to 11.7) and disease-free survival (DFS; HR, 3.28; 95% CI, 1.22 to 8.80). Five-year survival for poor mrTRG was 27% versus 72% (P = .001), and DFS for poor mrTRG was 31% versus 64% (P = .007). Preoperative MRI-predicted CRM independently predicted local recurrence (LR; HR, 4.25; 95% CI, 1.45 to 12.51). Five-year survival for poor post-treatment pathologic T stage (ypT) was 39% versus 76% (P = .001); DFS for the same was 38% versus 84% (P = .001); and LR for the same was 27% versus 6% (P = .018). The 5-year survival for involved pCRM was 30% versus 59% (P = .001); DFS, 28 versus 62% (P = .02); and LR, 56% versus 10% (P = .001). Pathology node status did not predict outcomes. CONCLUSION MRI assessment of TRG and CRM are imaging markers that predict survival outcomes for good and poor responders and provide an opportunity for the multidisciplinary team to offer additional treatment options before planning definitive surgery. Postoperative histopathology assessment of ypT and CRM but not post-treatment N status were important postsurgical predictors of outcome.

MRI After Treatment of Locally Advanced Rectal Cancer: How to Report Tumor Response—The MERCURY Experience

OBJECTIVE The Magnetic Resonance Imaging and Rectal Cancer European Equivalence (MERCURY) Study validated the use of MRI for posttreatment staging and its correlation with survival outcomes. As a consequence, reassessment of MRI scans after preoperative therapy has implications for surgical planning, the timing of surgery, sphincter preservation, deferral of surgery for good responders, and development of further preoperative treatments for radiologically identified poor responders. CONCLUSION In this article we report a validated systematic approach to the interpretation of MR images of patients with rectal cancer after chemoradiation.

Rectal cancer: primary staging and assessment after chemoradiotherapy.

Rectal cancer staging is based on 2 principles. The first is an anatomic definition of the tumor allowing for surgical planning. The second is prognostic stage grouping. A given prognostic stage carries different risks of both local and distant recurrence, a selective and tailored approach to preoperative therapy is appropriate. Increasingly, selective approaches enable an overall reduction in morbidity from overtreatment, while allowing aggressive treatment of high-risk patients. Therefore, the aim of preoperative staging is to accurately and reproducibly differentiate between good and poor prognosis tumors. In the preoperative setting, superficial and flat rectal cancers are probably best initially staged using endoscopic ultrasound, and where available magnetic resonance imaging is used for all other rectal cancers because of its proven high sensitivity and specificity in identifying poor-risk patients based on circumferential margin status, the depth of extramural spread, extramural venous invasion, and nodal status. Restaging after neoadjuvant therapy is a challenge to all modalities because of radiation-induced changes, namely fibrosis, edema, inflammation, and necrosis. However, emerging data suggest that reassessment using a combination of high-resolution magnetic resonance imaging, diffusion-weighted imaging, and positron emission tomography/computed tomography scanning may help to provide valuable prognostic information before definitive surgery.

Urethral Injuries after Pelvic Trauma: Evaluation with Urethrography

Urethral injury is a common complication of pelvic trauma that, if undiagnosed, may lead to significant long-term morbidity. Segments of the urethra that are near the pubic rami and the puboprostatic ligaments are particularly vulnerable. Although computed tomography is commonly used for the initial imaging evaluation of patients with polytrauma, urethral injury is better assessed and classified by using urethrography. Complete urethral imaging is especially important at presentation because the insertion of a transurethral bladder catheter may exacerbate an existing injury (eg, cause a partial urethral tear to become a complete transection). However, even for radiologists who are familiar with standard technique, urethrography after pelvic trauma may be particularly challenging because the patient is immobile or a surgical fixation device or indwelling urethral catheter is present. Various methods may used to overcome these difficulties and ensure that optimal images are obtained so that a correct diagnosis can be made without additional imaging evaluations.

Can a novel MRI staging system for low rectal cancer aid surgical planning

BACKGROUND: Low rectal cancers are associated with worse outcomes in comparison with mid and upper rectal tumors. OBJECTIVE: This study aimed to assess the predictive accuracy of MRI in identifying the correct surgical approach based on the mesorectal and extralevator planes. DESIGN: This study involved the retrospective analysis of MRI and histopathology data of 33 patients with low rectal cancer, with the use of an anatomically based staging system. Three radiologists reported on the available surgical planes of excision based on the predicted relationship of tumor to key anatomical features. MRI-predicted planes of excision were then compared with the histopathological planes actually required, with the use of the same staging criteria. SETTINGS: The study was conducted at 4 English district general hospitals. PATIENTS: Unselected patients with low rectal cancer, all of whom were participants in a multicenter study, were eligible for this study. MAIN OUTCOME MEASURES: The main outcome measured was the accuracy of operative plane prediction on MRI. RESULTS: On pathological analysis, the mesorectal plane would have been sufficient to achieve a clear margin in 28 of 33 (84.9%) of cases. The extralevator plane was required in 5 of 33 (15.1%). Planes were correctly predicted by MRI in 29 of 33 cases by radiologist 1 and 24 of 33 cases by radiologists 2 and 3 with an accuracy of 87.9% and 72.7%. Overstaging (extralevator plane predicted when a mesorectal plane would have sufficed) occurred in 3 of 33 and 7 of 33 cases. Understaging (mesorectal plane predicted when an extralevator plane was required) occurred in 1 of 33 and 2 of 33 cases. The positive and negative predictive values of MRI in determining the histopathological plane of excision required were 57% and 96% for radiologist 1 and 30% and 91% for radiologists 2 and 3. LIMITATIONS: This study was limited by its retrospective nature and its relatively small patient numbers. No account was taken of postoperative function when recommending the surgical plane. CONCLUSIONS: This supports an anatomically based MRI staging system for low rectal cancer to predict the planes of surgical excision. This may help to reduce margin positivity and to improve outcome in patients with low rectal cancer.

Diagnostic accuracy and value of magnetic resonance imaging (MRI) in planning exenterative pelvic surgery for advanced colorectal cancer

PURPOSE To assess the diagnostic accuracy of magnetic resonance imaging (MRI) in detecting colorectal tumour invasion according to seven intrapelvic compartments for planning exenterative pelvic surgery. METHOD Sixty-three consecutive patients underwent preoperative MRI planning for exenterative surgery, defined as operative excision beyond conventional mesenteric planes for locally advanced (n=23) and recurrent (n=41) pelvic colorectal cancer. The institutional research committee approved of the study and waived the need for a consent form as the images were retrospectively assessed. Two radiologists reported tumour invasion for each of seven anatomic surgical resection compartments, blinded to histopathology and the intraoperative findings. Sensitivity, specificity and predictive values were calculated for the seven intrapelvic compartments. Cox regression analysis was used to calculate the risk of death and recurrence. Overall interobserver agreement was assessed using Cohens Kappa coefficient (k). RESULTS The sensitivity of MRI was ≥93.3% in all but the lateral compartment where it was 89.3%. Specificity for the posterior (82.2%) and anterior compartments below the peritoneal reflection (86.4%) was lower compared to the other compartments. Agreement between the two radiologists was found to be good or very good for all compartments (k>0.72). An MRI diagnosis of tumour invasion in the anterior compartment above the peritoneal reflection was associated with a poorer survival (p=0.012). CONCLUSION MRI is accurate in predicting the extent of colorectal tumour within the pelvis and therefore can be used to determine the type of surgery required for curative resection. It should always be used to stage patients with advanced colorectal pelvic cancer.

Imaging in the Follow-Up of Renal Cell Carcinoma

OBJECTIVE The purpose of this article is to review the follow-up strategies used after treatment or for active surveillance of renal cell cancer and to describe the normal posttreatment findings and the distribution and the signs of relapsed disease. CONCLUSION Imaging follow-up protocols should be tailored according to the clinical scenario. Further experience is necessary to better refine imaging strategies, especially regarding follow-up of patients after thermal ablation or antiangiogenic therapy and those being maintained on active surveillance.

Centrally Infiltrating Renal Masses on CT: Differentiating Intrarenal Transitional Cell Carcinoma From Centrally Located Renal Cell Carcinoma

OBJECTIVE The objective of our study was to retrospectively determine the accuracy of CT for differentiating intrarenal transitional cell carcinoma (TCC) from centrally located renal cell carcinoma (RCC) and to define the most discriminating diagnostic CT features. MATERIALS AND METHODS CT studies of 98 pathologically proven central renal tumors (64 centrally located RCCs and 34 intrarenal TCCs) seen over 5 years at three university hospitals were reviewed by five specialty-trained radiologists who were blinded to the final diagnosis. Multiple CT features and global impression were graded on a 4-point score. The sensitivity and specificity of each feature and of global assessment were calculated and compared using receiver operating characteristic (ROC) analysis. Interobserver agreement (kappa values) was also calculated for each parameter. RESULTS All five readers recognized intrarenal TCCs with a high diagnostic accuracy (sensitivity, 90%; specificity, 90%; area under ROC curve [AUC], 0.80-0.95 for global assessment) with moderate-to-excellent interobserver agreement (κ = 0.72-1). Six CT features were most diagnostically specific for identifying intrarenal TCCs: tumor centered within the collecting system; focal filling defect in the pelvicalyceal system; preserved renal shape; absence of cystic or necrotic change; homogeneous tumor enhancement; and tumor extension toward the ureteropelvic junction (sensitivity, 68-82%; specificity, 79-89%; AUC, 0.75-0.84). There was moderate-to-good agreement among the readers over all these features (κ = 0.44-0.69). CONCLUSION Intrarenal TCC can be recognized with a high accuracy on CT; global impression showed the best diagnostic performance. A solid, homogeneously enhancing mass that is centered on the collecting system and extends toward the ureteropelvic junction combined with a focal pelvicalyceal filling defect and preserved renal outline is more likely to be an intrarenal TCC than a centrally located RCC.

Synchronous Renal Masses in Patients With a Nonrenal Malignancy: Incidence of Metastasis to the Kidney Versus Primary Renal Neoplasia and Differentiating Features on CT

OBJECTIVE The purpose of this study was to establish the contemporaneous frequency of metastases within the kidney as opposed to primary renal tumors in patients with an active primary nonrenal malignancy and to identify the differentiating features. MATERIALS AND METHODS We retrospectively identified all patients with an active primary nonrenal malignancy (group 1) who had also undergone at least 2 contrast-enhanced abdominal CT examinations spaced 1 year apart. The radiologic and pathologic data of these cases were reviewed and the incidence of metastasis to the kidney versus primary renal tumors established. These data were compared with a separate group who presented with primary renal malignancy from the outset (group 2). RESULTS In the study were 2340 patients with primary nonrenal malignancy (group 1) and 231 patients with a primary renal malignancy (group 2). For group 1, the mean age was 63 years and 51% were men; for group 2, the mean age was 59 years, and 58% were men. The differences were not statistically significant. Thirty-six patients in group 1 had a malignant renal mass; 21 were a result of kidney metastasis and the remaining 15 were a synchronous primary renal tumor (0.9% vs 0.6%). The kidney was the eighth most common site of metastatic spread. Metastases to the kidney were statistically more likely with higher tumor stage of the primary nonrenal malignancy (68% vs 46%, p = 0.0006) and in those with other sites of metastasis (p = 0.012, positive likelihood ratio [LR+] = 6.75). Compared with primary renal tumors, metastases to the kidney were more often solid (86% vs 53%, p = 0.019, LR+ = 3.7) and endophytic (76% vs 33%, p = 0.017, LR+ = 2.29). There were too few cases with calcification and bilateral tumors to reach a statistically significant conclusion. Tumor size, polar predominance, and enhancement pattern were similar in the two groups. The primary renal tumors seen in group 1 versus group 2 were similar regarding age and sex distribution, cell type, median size, and tumor stage. CONCLUSION Metastases to the kidney are uncommon in modern radiologic practice (0.9%, 21/2340 in this study), and a renal mass seen in a patient with nonrenal malignancy is nearly as likely to be an incidental primary renal tumor. Metastasis is more likely in those with higher tumor stage or if other viscera are also affected and is usually an asymptomatic, small, endophytic, and solid mass. If a renal mass seen in a patient with primary nonrenal malignancy proves to be a synchronous primary renal tumor, its cell type and stage will be similar to sporadic primary renal tumors.

Radiologic Appearance of Hereditary Adrenal and Extraadrenal Paraganglioma

OBJECTIVE There is a wide spectrum of established and emerging genetic mutations associated with intraadrenal and extraadrenal paragangliomas. In this review, we present the typical radiologic patterns of disease associated with six well-characterized genetic mutations and discuss other inherited and nonfamilial syndromes currently under characterization. CONCLUSION Contrary to previous understanding, recent genotype advances suggest that the majority of paragangliomas may be genetically predisposed.