Acinarization (parenchymal blush) observed during secretin-enhanced MRCP: clinical implications.

OBJECTIVE: T2 hyperintensity of pancreatic acini during secretin-enhanced MRCP is called "acinarization." We sought to determine the clinical significance of this finding. MATERIALS AND METHODS: Patients were selected if the radiology report included the phrases "acin*" (where * represented a wild card search) or "blush" using the institution's customized lexicon-search software. Sixty-seven consecutive patients without acinarization on secretin-enhanced MRCP who also underwent ERCP were enrolled as the control group. The intensity of acinarization was classified into three groups: grade 0, no visible acinarization; grade 1, barely visible parenchymal hyperintensity; or grade 2, easily visible parenchymal hyperintensity. ERCP findings of ductal abnormalities and basal pancreatic sphincter manometry were recorded. RESULTS: There were higher frequencies of divisum (p = 0.001) and of a clinical history of recurrent acute pancreatitis (p < 0.001) and higher basal pancreatic sphincter of Oddi manometric pressure measurements (p = 0.008) in the acinarization group. There was no difference in the frequency of ERCP-defined chronic pancreatitis (p = 0.10) between the groups. In patients with acinarization, a higher mean sphincter pressure was seen in patients with more intense acinarization than in those with faint acinarization, but this difference was not significant (p = 0.22). Ampullary tumors were found in four patients with acinarization. CONCLUSION: Acinarization probably occurs in patients with a propensity for increased pancreatic ductal pressure (i.e., patients with divisum, elevated basal pancreatic sphincter pressure, ampullary tumor) and adequate exocrine function (absence of severe chronic pancreatitis).

Flaps, slings, and other things: CT after reconstructive surgery--expected changes and detection of complications.

OBJECTIVE: This article will discuss the typical CT appearance of myocutaneous surgically placed flaps as well as some frequently encountered complications of this surgery. We will discuss the appearance of relatively new, but increasingly encountered, nonnative materials used in reconstructive surgery, such as spacers, bulking agents, hemostatic agents, and other reconstructive materials. CONCLUSION: Oncologic surgery often requires reconstruction using myocutaneous flaps. Therefore, an understanding of the type of reconstruction performed is important for the accuracy of postoperative radiologic interpretation to recognize presence of a flap to avoid misdiagnosis of tumor recurrence.

Peritoneal and retroperitoneal anatomy and its relevance for cross-sectional imaging.

It is difficult to identify normal peritoneal folds and ligaments at imaging. However, infectious, inflammatory, neoplastic, and traumatic processes frequently involve the peritoneal cavity and its reflections; thus, it is important to identify the affected peritoneal ligaments and spaces. Knowledge of these structures is important for accurate reporting and helps elucidate the sites of involvement to the surgeon. The potential peritoneal spaces; the peritoneal reflections that form the peritoneal ligaments, mesenteries, and omenta; and the natural flow of peritoneal fluid determine the route of spread of intraperitoneal fluid and disease processes within the abdominal cavity. The peritoneal ligaments, mesenteries, and omenta also serve as boundaries for disease processes and as conduits for the spread of disease.

Histopathologic correlation of pancreatic fibrosis with pancreatic magnetic resonance imaging quantitative metrics and Cambridge classification.

PURPOSE: To determine the correlation of the T1-weighted signal intensity ratio (T1 SIR, or T1 Score) and arterial-to-delayed venous enhancement ratio (ADV ratio) of the pancreas with pancreatic fibrosis on histopathology. METHODS: Sixty consecutive adult CP patients who had an MRI/MRCP study prior to pancreatic surgery were analyzed. Three blinded observers measured T1 SIR of pancreas to spleen (T1 SIR p/s), pancreas-to-paraspinal muscle (T1 SIR p/m), ADV ratio, and Cambridge grade. Histopathologic grades were given by a gastrointestinal pathologist using Ammann's fibrosis score. Statistical analysis included Spearman's correlation coefficient of the T1 SIR, ADV ratio, Cambridge grade with the fibrosis score, and weighted kappa for interobserver agreement. RESULTS: The study population included 31 female and 29 male patients, with an average age of 52.1 (26-78 years). Correlations between fibrosis score and T1 SIR p/s, T1 SIR p/m, and ADV ratio were ρ = - 0.54 (p = 0.0001), ρ = - 0.19 (p = 0.19), and ρ = - 0.39 (p = 0.003), respectively. The correlation of Cambridge grade with fibrosis score was ρ = 0.26 (p = 0.07). There was substantial interobserver agreement (weighted kappa) for T1 SIR p/s (0.78), T1 SIR p/m (0.71), and ADV ratio (0.64). T1 SIR p/s of ≤ 1.20 provided a sensitivity of 74% and specificity of 50% (AUC: 0.74), while ADV ratio of ≤ 1.10 provided a sensitivity of 75% and specificity of 55% (AUC: 0.68) to detect a fibrosis score of ≥ 6. CONCLUSION: There is a moderate negative correlation between the T1 Score (SIR p/s) and ADV ratio with pancreatic fibrosis and a substantial interobserver agreement. These parenchymal metrics show a higher correlation than the Cambridge grade.

Characterization of adrenal masses with diffusion-weighted imaging.

OBJECTIVE: The purpose of this article is to assess the role of diffusion-weighted MRI in characterizing adrenal masses. MATERIALS AND METHODS: A retrospective review of the MRI database from August 2007 to July 2009 was performed. The MRI examinations of 48 patients, with 49 lesions, were reviewed independently and blindly by two experienced abdominal radiologists who measured the signal intensities on in-phase and opposed-phase T1-weighted imaging and apparent diffusion coefficient (ADC). ADC measurements and quantitative parameters of chemical shift imaging (signal intensity index and adrenal-to-spleen ratio) were assessed separately and in combination. Lesions with indeterminate signal intensity index (< 16.5%) were considered benign if ADC was greater than or equal to 1.0 × 10(-3) mm(2)/s and malignant if ADC was less than 1.0 × 10(-3) mm(2)/s. Stepwise logistic regression analysis and receiver operating characteristic curves analysis were performed. RESULTS: There were 12 malignant and 37 benign lesions. On multivariate analysis, the only significant predictors of lesion status were signal intensity index from reviewer 2 (p = 0.05) and lesion size (p = 0.04); ADC values were not found to be useful. On receiver operating characteristic curve analysis, there was no significant difference in area under the curve for ADC, signal intensity index, adrenal-to-spleen ratio, or the combined signal intensity index and ADC assessment. For lesions that were indeterminate according to signal intensity index, ADC values greater than 1.50 × 10(-3) mm(2)/s were found only in benign lesions, and nine of 11 lesions with ADC less than 1.0 × 10(-3) mm(2)/s were malignant. CONCLUSION: In general, ADC values are not useful in differentiating adrenal lesions. However, when ADC values are applied to lesions that are indeterminate on signal intensity index, they may help in differentiating a subset of benign and malignant lesions.

T1 mapping for the diagnosis of early chronic pancreatitis: correlation with Cambridge classification system.

OBJECTIVE: This study aims to determine if T1 relaxation time of the pancreas can detect parenchymal changes in early chronic pancreatitis (CP). METHODS: This study retrospectively analyzed 42 patients grouped as no CP (Cambridge 0; n = 21), equivocal (Cambridge 1; n = 12) or mild CP (Cambridge 2; n = 9) based on magnetic resonance cholangiopancreatography findings using the Cambridge classification as the reference standard. Unenhanced T1 maps were acquired using a three-dimensional dual flip-angle gradient-echo technique on the same 1.5 T scanner with the same imaging parameters. RESULTS: There was no significant difference between the T1 relaxation times of Cambridge 0 and 1 group (p = 0.58). There was a significant difference (p = 0.0003) in the mean T1 relaxation times of the pancreas between the combined Cambridge 0 and 1 (mean = 639 msec, 95% CI: 617, 660) and Cambridge 2 groups (mean = 726 msec, 95% CI: 692, 759). There was significant difference (p = 0.0009) in the mean T1 relaxation times of the pancreas between the Cambridge 0 (mean = 636 msec, 95% CI: 606, 666) and Cambridge 2 groups (mean = 726 msec, 95% CI: 692,759) as well as between Cambridge 1 (mean = 643 msec, 95% CI: 608, 679) and Cambridge 2 groups (mean = 726 msec, 95% CI: 692,759) (p = 0.0017). Bland-Altman analysis showed measurements of one reader to be marginally higher than the other by 15.7 msec (2.4%, p = 0.04). CONCLUSION: T1 mapping is a practical method capable of quantitatively reflecting morphologic changes even in the early stages of chronic pancreatitis, and demonstrates promise for future implementation in routine clinical imaging protocols. ADVANCES IN KNOWLEDGE: T1 mapping can distinguish subtle parenchymal changes seen in early stage CP, and demonstrates promise for implementation in routine imaging protocols for the diagnosis of CP.

Pancreatic cystic neoplasms and post-inflammatory cysts: interobserver agreement and diagnostic performance of MRI with MRCP.

PURPOSE: We aimed to answer several clinically relevant questions; (1) the interobserver agreement, (2) diagnostic performance of MRI with MRCP for (a) branch duct intraductal papillary mucinous neoplasms (BD-IPMN), mucinous cystic neoplasms (MCN) and serous cystic neoplasms (SCN), (b) distinguishing mucinous (BD-IPMN and MCN) from non-mucinous cysts, and (c) distinguishing three pancreatic cystic neoplasms (PCN) from post-inflammatory cysts (PIC). METHODS: A retrospective analysis was performed at a tertiary referral center for pancreatic diseases on 71 patients including 44 PCNs and 27 PICs. All PCNs were confirmed by surgical pathology to be 17 BD-IPMNs, 13 MCNs, and 14 SCNs. Main duct and mixed type IPMNs were excluded. Two experienced abdominal radiologists blindly reviewed all the images. RESULTS: Sensitivity of two radiologists for BD-IPMN, MCN and SCN was 88-94%, 62-69% and 57-64%, specificity of 67-78%, 67-78% and 67-78%, and accuracy of 77-82%, 65-75% and 63-73%, respectively. There was 80% sensitivity, 63-73% specificity, 70-76% accuracy for distinguishing mucinous from non-mucinous neoplasms, and 73-75% sensitivity, 67-78% specificity, 70-76% accuracy for distinguishing all PCNs from PICs. There was moderate-to-substantial interobserver agreement (Cohen's kappa: 0.65). CONCLUSION: Two experienced abdominal radiologists had moderate-to-high sensitivity, specificity, and accuracy for BD-IPMN, MCN, and SCN. The interobserver agreement was moderate-to-substantial. MRI with MRCP can help workup of incidental pancreatic cysts by distinguishing PCNs from PICs, and premalignant mucinous neoplasms from cysts with no malignant potential.

Can radiologists and urologists reliably determine renal mass histology using standard preoperative computed tomography imaging?

PURPOSE: To determine the extent to which radiologists and urologists can predict histology using multiphasic CT imaging. METHODS: Patients with a preoperative multiphasic CT undergoing surgery for a renal mass were identified between 2003 and 2013. Tumors >10 cm, locally advanced or metastatic disease, and patients managed by reviewers were excluded. A survey and deidentified scans were provided to reviewers. Sensitivity and accuracy in predicting histology was calculated for each reviewer. Correlation was assessed by the Fleiss kappa coefficient. Multivariable logistic regression determined factors associated with predictive accuracy for final pathology. RESULTS: There were 120 patients who met criteria. Mean tumor size was 3.3 cm; there were 102 (85%) that were malignant, and 73% of these were clear-cell renal-cell carcinoma (RCC). The most common benign histology was angiomyolipoma (n=10, 56%) followed by oncocytoma (n=5, 28%). Correlation among reviewers was statistically fair for predicting malignant (κ=0.25) and final pathology (κ=0.22). Sensitivity for predicting malignant masses was 90%. Reviewers accurately predicted malignant pathology in 82% of cases and predicted final pathology in 58% of cases. Adjusted for size, scan type, and reviewer, clear-cell RCC vs benign histology was associated with 21 times increased odds of accurate pathologic identification (P<0.001). CONCLUSIONS: Urologists and radiologists were able to accurately identify malignant histology in 82% of cases, although sensitivity for malignant histology was 90%. Developing a preoperative nomogram for identification of clear-cell RCC may be feasible and should be further explored.

Transgluteal CT-Guided Percutaneous Renal Access for Percutaneous Nephrolithotomy in a Pelvic Horseshoe Kidney.

CT-guided percutaneous renal access has been described as a safe and effective access technique in patients with complex anatomy, including ectopic kidney, retrorenal colon, spinal dysraphism, hepatomegaly, and splenomegaly. In comparison to conventional intraoperative fluoroscopic-guided access, CT imaging allows for delineation of surrounding structures that are at risk for injury during percutaneous access. However, previous reports indicate that pelvic kidneys might be inaccessible percutaneously without laparoscopic assistance. Herein, we present a novel transgluteal route to renal access for percutaneous nephrolithotomy (PCNL) in a patient with a pelvic horseshoe kidney and severe spinal deformity.

R.E.N.A.L. Nephrometry scoring: how well correlated are urologist, radiologist, and collaborator scores?

PURPOSE: R.E.N.A.L. Nephrometry Score (NS) is an imaging-based (CT/MRI) scoring system commonly used by urologists to standardize the reporting of renal masses by enabling quantification of anatomical characteristics. We sought to examine the inter-rater correlation of NS between urologists, radiologists, and tumor-board collaborators. METHODS: We identified adult patients undergoing partial or radical nephrectomy over 10 years (n=2450). Patients with autosomal dominant polycystic kidney disease (ADPKD), metastatic disease, masses >10 cm, and studies in which the study urologists or radiologists partook in patient care were excluded. Preoperative imaging was evaluated and patients with multiphasic CT available were included. Scans were provided to the reviewers to evaluate with a R.E.N.A.L. nephrometry questionnaire. Results were analyzed using kappa correlation coefficients. RESULTS: One hundred twenty patients met inclusion criteria with mean age of 59.5 years. The majority of cases were partial nephrectomies (72%). Eighty-five percent of the tumors were malignant, with 26% having high-grade histology. The mean (standard deviation) overall NS was 6.8 (1.9) with fair correlation among reviewers (κ=0.222). Collaborators had the highest inter-rater correlation, ranging from 0.41 to 0.84 for NS component scores, compared with 0.42-0.85 for radiologists and 0.36-0.86 for urologists. "R" scores were best correlated (κ>0.8). NS correlation ranged between 0.16 and 0.31 for the groups while the NS complexity category correlation ranged between 0.50 and 0.61. CONCLUSIONS: Despite being naive to NS, inter-radiologist scoring patterns were better correlated than inter-urologist. The urologist and radiologist collaborating in tumor board showed the highest agreement, suggesting that a multidisciplinary approach in the characterization of renal masses may provide benefit to patient management.