Sandeep Hedgire

Noninvasive mapping of pancreatic inflammation in recent-onset type-1 diabetes patients

Significance We describe a readily exportable method for noninvasive imaging of the pancreatic inflammation underlying type-1 diabetes (T1D), based on MRI of the clinically approved magnetic nanoparticle ferumoxytol. This approach, which reflects nanoparticle uptake by macrophages in the inflamed pancreatic lesion, has been validated rigorously in mouse T1D models. Methodological advances reported here include extensive optimization of image acquisition and improved MRI registration and visualization technologies. A proof-of-principle study revealed a clear difference in whole-pancreas nanoparticle accumulation in patients with recent-onset T1D versus healthy controls and pronounced intra- and interpancreatic signal heterogeneity in patients. Noninvasive generation of 3D, high-resolution maps of pancreatic inflammation should prove invaluable in assessing T1D progression and as an indicator of response to therapy. The inability to visualize the initiation and progression of type-1 diabetes (T1D) noninvasively in humans is a major research and clinical stumbling block. We describe an advanced, exportable method for imaging the pancreatic inflammation underlying T1D, based on MRI of the clinically approved magnetic nanoparticle (MNP) ferumoxytol. The MNP-MRI approach, which reflects nanoparticle uptake by macrophages in the inflamed pancreatic lesion, has been validated extensively in mouse models of T1D and in a pilot human study. The methodological advances reported here were enabled by extensive optimization of image acquisition at 3T, as well as by the development of improved MRI registration and visualization technologies. A proof-of-principle study on patients recently diagnosed with T1D versus healthy controls yielded two major findings: First, there was a clear difference in whole-pancreas nanoparticle accumulation in patients and controls; second, the patients with T1D exhibited pronounced inter- and intrapancreatic heterogeneity in signal intensity. The ability to generate noninvasive, 3D, high-resolution maps of pancreatic inflammation in autoimmune diabetes should prove invaluable in assessing disease initiation and progression and as an indicator of response to emerging therapies.

Pancreatic neuroendocrine tumors in patients with tuberous sclerosis complex.

Larson AM, Hedgire SS, Deshpande V, Stemmer‐Rachamimov AO, Harisinghani MG, Ferrone CR, Shah U, Thiele EA. Pancreatic neuroendocrine tumors in patients with tuberous sclerosis complex.

Apparent diffusion coefficient as a non-invasive predictor of treatment response and recurrence in locally advanced rectal cancer

AIM To evaluate the role of pretreatment apparent diffusion coefficient (ADC) as a predictor of treatment response and local recurrence in patients with locally advanced rectal cancer who underwent neoadjuvant therapy. MATERIALS AND METHODS Forty-nine patients who underwent preoperative diffusion-weighted magnetic resonance imaging (MRI) followed by neoadjuvant chemoradiation and surgery were enrolled in the study. The mean tumour ADC was measured independently from multiple, non-overlapping regions of interest (ROIs) to cover the entire tumour area on a single section by two radiologists and patients were followed postoperatively for a median of 16.4 months. Diagnostic accuracy of ADC for predicting treatment response and recurrence was evaluated using the area under the receiver-operating characteristic (ROC) curve, sensitivity, specificity, and predictive values. Univariate and multivariate analyses including clinical tumour (cT) staging, carcinoembryonic antigen (CEA) level, lymph-node involvement, tumour grade, surgical margin, vascular involvement, and ADC were performed with respect to recurrence. Interobserver agreement of ADC values was assessed. RESULTS Twenty patients showed response to neoadjuvant therapy and recurrence was noted in 17 patients. Low pretreatment ADC, MRI findings of cT4 staging, and node involvement were significantly related to poor treatment response. Sensitivity and specificity of ADC = 0.833 × 10(-3) mm(2)/s for prediction of treatment response was 75 and 48% for reader 1 and 65 and 52% for reader 2, respectively. Univariate and multivariate analyses identified pretreatment tumour ADC as the only predictive factor for recurrence. Sensitivity and specificity of ADC = 0.833 × 10(-3) mm(2)/s for prediction of recurrence was 86 and 77% for reader 1 and 80 and 69% for reader 2, respectively. Interobserver agreement for measuring ADC was good with a kappa value of 0.70. CONCLUSION Pretreatment rectal tumour ADC values may be an early biomarker for predicting treatment response and local recurrence in patients who underwent neoadjuvant chemoradiation.

Predictive Value of Chemical-Shift MRI in Distinguishing Clear Cell Renal Cell Carcinoma From Non-Clear Cell Renal Cell Carcinoma and Minimal-Fat Angiomyolipoma

OBJECTIVE The purpose of this study was to evaluate the diagnostic performance of chemical-shift MRI in the differentiation of clear cell renal cell carcinoma (RCC) from minimal-fat angiomyolipoma (AML) and non-clear cell RCC. MATERIALS AND METHODS In this retrospective study, 97 patients with solid renal tumors without macroscopic fat and with a pathologic diagnosis of clear cell RCC (n = 40), non-clear cell RCC (n = 31), or minimal-fat AML (n = 26) who had undergone renal chemical-shift MRI were included. Size, location, morphology, and signal intensity (SI) of the tumors and the contralateral normal kidneys on T2-weighted and in-phase and opposed-phase images were recorded by readers blinded to the pathology. Percentage tumor-to-renal parenchymal SI drop (percentage SI drop) was calculated and correlated to tumor histology. The statistical analysis was done using Kruskal-Wallis, one-way ANOVA, chi-square, and Fisher exact tests. RESULTS The percentage SI drop was significantly higher in clear cell RCC compared with non-clear cell RCC and minimal-fat AML (p < 0.001). Percentage SI drop of greater than 20% had 57.5% sensitivity, 96.5% specificity, and 92% positive predictive value (PPV); and percentage SI drop greater than 29% had 40% sensitivity and 100% specificity for diagnosis of clear cell RCC within the cohort of clear cell RCC, minimal-fat AML, and non-clear cell RCC. A significant proportion of minimal-fat AML (46.2%) displayed homogeneous low T2-weighted SI as opposed to clear cell RCC (5%) and non-clear cell RCC (29%) (p < 0.001). CONCLUSION The percentage SI drop on chemical-shift MRI had high specificity and moderate sensitivity in predicting clear cell RCC over non-clear cell RCC and minimal-fat AML. A percentage SI drop greater than 20% in a renal mass without macroscopically visible fat has high PPV for clear cell RCC over minimal-fat AML and non-clear cell RCC. Among morphologic features, homogeneous low T2 SI favors minimal-fat AML over RCC.

Is Early Colonoscopy Beneficial in Patients With CT-Diagnosed Diverticulitis?

OBJECTIVE The purpose of this study was to establish CT criteria as an indication for colonoscopy in patients with acute diverticulitis. MATERIALS AND METHODS The study was composed of patients diagnosed with acute diverticulitis on contrast-enhanced CT (CECT) from January 2000 to December 2004. Patients without subsequent colonoscopy were excluded. Findings on CT were correlated with patient outcomes over follow-up. Sensitivity, specificity, and predictive values of the imaging parameters for prediction of colon cancer were calculated. Outcomes were also compared between men and women. RESULTS Of 1034 patients with a CT diagnosis of diverticulitis, 402 (235 women and 167 men; mean age, 63.3 years) had available endoscopic colonic evaluation after CECT. The mean follow-up was 5.3 years. Seventy-eight patients had polyps (71% adenomatous) and nine patients (2.2%) were diagnosed with colon cancer (seven women, two men). The odds ratio for diagnosis of colon cancer was 23.35 in patients with mesenteric or retroperitoneal lymphnodes, 4.67 for abscess, and 24.43 in patients with obstruction and localized mass reported on CT. A significant correlation was found between the location of diverticulitis and cancer (p < 0.001). The diagnosis of cancer was made within 6 months from the date of CECT in eight patients. The odds of cancer were 2.5 times higher in women. CONCLUSION On the basis of the significant correlation of complicated diverticulitis or presence of lymph nodes with new diagnoses of colon cancer, we recommend early colonoscopy in patients with wall thickness more than 6 mm, abscess, obstruction, or lymph nodes seen on CECT.

Arterial interventions in gastrointestinal bleeding.

The diagnosis and management of gastrointestinal (GI) bleeding are complicated. A multitude of pathologic processes results in GI bleeding, and often, the bleeding is intermittent in nature. Of the available diagnostic tools, angiography has been the gold standard. Management of patients requires a multidisciplinary approach involving gastroenterologists, interventional radiologists, and surgeons. Therapeutic arterial interventions include pharmacologic control with the use of intraarterial vasopressin, embolization with temporary and permanent embolizing materials, and catheter-induced vasospasm.

Enhanced primary tumor delineation in pancreatic adenocarcinoma using ultrasmall super paramagnetic iron oxide nanoparticle-ferumoxytol: an initial experience with histopathologic correlation.

Purpose To evaluate the role of ferumoxytol-enhanced magnetic resonance imaging (MRI) in delineating primary pancreatic tumors in patients undergoing preoperative neoadjuvant therapy. Materials and methods Eight patients with pancreatic adenocarcinoma were enrolled in this study, and underwent MRI scans at baseline, immediate post, and at the 48 hour time point after ferumoxytol injection with quantitative T2* sequences. The patients were categorized into two groups; group A received preoperative neoadjuvant therapy and group B did not. The T2* of the primary pancreatic tumor and adjacent parenchyma was recorded at baseline and the 48 hour time point. After surgery, the primary tumors were assessed histopathologically for fibrosis and inflammation. Results The mean T2* of the primary tumor and adjacent parenchyma at 48 hours in group A were 22.11 ms and 16.34 ms, respectively; in group B, these values were 23.96 ms and 23.26 ms, respectively. The T2* difference between the tumor and adjacent parenchyma in group A was more pronounced compared to in group B. The tumor margins were subjectively more distinct in group A compared to group B. Histopathologic evaluation showed a rim of dense fibrosis with atrophic acini at the periphery of the lesion in group A. Conversely, intact tumor cells/glands were present at the periphery of the tumor in group B. Conclusion Ferumoxytol-enhanced MRI scans in patients receiving preoperative neoadjuvant therapy may offer enhanced primary tumor delineation, contributing towards achieving disease-free margin at the time of surgery, and thus improving the prognosis of pancreatic carcinomas.

Pelvic Nodal Imaging

Detection of nodal metastases in men with pelvic urogenital malignancies is important for accurate staging and has therapeutic and prognostic implications. Knowledge of clinical anatomy of these nodes and the lymphatic pathways is critical for assigning the correct N or M staging and to assess the treatment response. Both computed tomography and magnetic resonance imaging use size and morphologic criteria for nodal characterization. The limitations of these criteria have formed basis newer functional imaging tools. This article focuses on the clinical anatomy, pathways of lymphatic spread of malignancies, current criteria, and newer advances in imaging of male pelvic nodes.

Hepatic manifestations of tuberous sclerosis complex: a genotypic and phenotypic analysis.

Black ME, Hedgire SS, Camposano S, Paul E, Harisinghani M, Thiele EA. Hepatic manifestations of tuberous sclerosis complex: a genotypic and phenotypic analysis.

Tuberculosis--the great mimicker.

Tuberculosis is an immense health problem in the developing world, and it remains a health care challenge in the developed world. It can affect virtually any organ system in the body. Diagnosis of tuberculosis is often difficult. Many patients with tuberculosis present with nonspecific symptoms, negative purified protein derivative skin test result, and negative findings on culture specimens. Cross-sectional imaging with ultrasound, multidetector computed tomography, and magnetic resonance imaging plays an important role in the diagnosis of tuberculosis. Tuberculosis demonstrates a variety of radiologic features depending on the organ involved and can mimic a number of other disease entities. Cross-sectional imaging alone is insufficient in reaching a conclusive diagnosis. Tuberculosis is a great mimicker as its radiologic manifestations can simulate numerous other diseases across the body systems. However, recognition and understanding of the common and uncommon radiologic manifestations of tuberculosis should alert considering tuberculosis in the high-risk population and correct clinical setting to enable appropriate treatment.