Kyung Mi Jang

Locally Advanced Rectal Cancer: Added Value of Diffusion-weighted MR Imaging for Predicting Tumor Clearance of the Mesorectal Fascia after Neoadjuvant Chemotherapy and Radiation Therapy

PURPOSE To evaluate the added value of diffusion-weighted (DW) imaging in combination with T2-weighted magnetic resonance (MR) imaging compared with T2-weighted imaging alone for predicting tumor clearance of the mesorectal fascia (MRF) after neoadjuvant chemotherapy and radiation therapy (CRT) in patients with locally advanced rectal cancer. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and informed consent was waived. Forty-five patients with rectal cancer with clinically suspected MRF invasion who underwent neoadjuvant CRT and subsequent surgery were enrolled. All patients underwent pre- and post-CRT 3.0-T rectal MR imaging with DW imaging. Two observers independently reviewed a set of T2-weighted images and a combined set of T2-weighted and DW images and rated them by using a five-point scale. Diagnostic performance was evaluated for each observer with receiver operating characteristic (ROC) curve analysis. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value (NPV) were assessed. The standard of reference was histopathologic findings in the surgical specimen. Pairwise comparison of the ROC curves was used to compare diagnostic performance between the two image sets; the McNemar test was used to compare accuracy, sensitivity, and specificity. RESULTS The diagnostic performance (area under the ROC curve [A(z)]) with respect to MRF tumor clearance of both observers improved significantly after additional review of DW images: A(z) improved from 0.770 to 0.918 (P = .017) for observer 1 and from 0.847 to 0.960 (P = .026) for observer 2. The diagnostic accuracy of DW combined with T2-weighted imaging (observer 1, 89% [40 of 45]; observer 2, 93% [42 of 45]), sensitivity (observer 1, 94% [31 of 33]; observer 2, 97% [32 of 33]) and NPV (observer 1, 82% [nine of 11]; observer 2, 91% [10 of 11]) were significantly higher than those of T2-weighted imaging alone (accuracy: observer 1, 40% [18 of 45], P < .001; observer 2, 69% [31 of 45], P = .022; sensitivity: observer 1, 21% [seven of 33], P < .001; observer 2, 67% [22 of 33], P = .002; NPV: observer 1, 30% [11 of 37], P = .013; observer 2, 45% [nine of 20], P = .025). Interobserver agreement of confidence levels was fair for T2-weighted imaging alone (κ = 0.212) but was excellent for the combined set of DW and T2-weighted images (κ = 0.880). CONCLUSION Adding DW imaging to T2-weighted imaging can improve the prediction of tumor clearance in the MRF after neoadjuvant CRT compared with T2-weighted imaging alone in patients with locally advanced rectal cancer.

Diagnostic accuracy and sensitivity of diffusion-weighted and of gadoxetic acid-enhanced 3-T MR imaging alone or in combination in the detection of small liver metastasis (≤ 1.5 cm in diameter).

Purpose:To compare the diagnostic accuracy and sensitivity of combined gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) with each imaging approach alone for detecting small hepatic metastases (⩽1.5 cm). Materials and Methods:Institutional review board approved this retrospective study and waived informed patient consent. Eighty-six patients with 179 liver metastases underwent liver MRI including unenhanced and gadoxetic acid-enhanced imaging and DWI at 3.0 T. Three image sets including unenhanced images—gadoxetic acid set (early dynamic and hepatocyte phase), DWI set, and the combined set—were analyzed independently and in consensus by 2 observers for detecting liver metastases using receiver operating characteristic analysis. Results:There was a tendency toward an increased diagnostic accuracy for the combined set (mean, 0.965) compared with that for each image set alone (mean, 0.911 for gadoxetic acid set; 0.926 for DWI set). The combined set showed better sensitivity (mean, 97.47%/95.0%: values on per-lesion/per-patient basis) than each imaging set alone (mean, 90.7%/83.7% for gadoxetic acid set; 91.6%/83.0% for DWI set) (P < 0.05) on both per-lesion basis and per-patient basis. All image sets showed similar positive predictive values. Conclusions:The combination of gadoxetic acid-enhanced MRI and DWI yielded better diagnostic accuracy and sensitivity in the detection of small liver metastasis than each magnetic resonance scan sequence alone.

The spectrum of benign esophageal lesions: imaging findings.

Benign esophageal lesions occur in various diseases. Barium studies are useful for the evaluation of mucosal surface lesions but provide little information about the extramucosal extent of disease. Computed tomography and magnetic resonance imaging, on the other hand, permit the assessment of wall thickness, mediastinal involvement, adjacent lymphadenopathy, and distant spread. In diseases such as fibrovascular polyps, duplication cysts, scleroderma, trauma, caustic esophagitis, hiatal hernia, esophageal diverticulum, achalasia, and paraesophageal varices, the findings of imaging studies are specific, obviating the need for further invasive diagnostic work-up. The advent of helical computed tomography and its volume data set allows the acquisition of multiplanar images, and magnetic resonance imaging is useful both for this and for tissue characterization. Thus, multiplanar cross-sectional imaging further extends the role of imaging modalities to the evaluation of benign esophageal lesions. Through an awareness of the multiplanar cross-sectional appearances of various benign esophageal lesions, the radiologist can play an important role in the detection, diagnosis, further diagnostic planning, and treatment of the diseases in which they occur.

Diagnostic Performance of CT in the Detection of Intestinal Ischemia Associated With Small-Bowel Obstruction Using Maximal Attenuation of Region of Interest

OBJECTIVE The purpose of this study was to assess the diagnostic performance of CT in the detection of intestinal ischemia associated with small-bowel obstruction using the maximal attenuation of a region of interest (ROI). MATERIALS AND METHODS Abdominal CT scans of 60 patients with small-bowel obstruction were retrospectively reviewed. The reference standard of the clinicopathologic groups was classified into four categories: no bowel necrosis, mucosal-submucosal necrosis, superficial muscle necrosis, and transmural necrosis. The viability of the small bowel on CT was evaluated by visual assessment using five categories (i.e., definitely intestinal ischemia, probably intestinal ischemia, possibly intestinal ischemia, equivocal CT results, and no intestinal ischemia) and by measurement of the maximal attenuation of an ROI at selected obstructed small-bowel loops on contrast-enhanced and unenhanced CT scans. Diagnostic performances were evaluated by one-way analysis of variance and receiver operating characteristic (ROC) curve analysis. RESULTS The sensitivity, specificity, positive and negative predictive values, and accuracy of visual assessment for intestinal ischemia were 91.7% (33/36), 66.7% (16/24), 80.5% (33/41), 84.2% (16/19), and 81.7% (49/60), respectively. The maximal attenuation of the ROIs on contrast-enhanced CT and the subtraction value between the maximal attenuation on contrast-enhanced CT and that on unenhanced CT scans at selected bowel were significantly different according to clinicopathologic group (p < 0.001). The area under the ROC curve of the maximal attenuation subtraction values between contrast-enhanced and unenhanced CT scans (0.995) was higher than that of visual assessment (0.908) for the detection of intestinal ischemia. CONCLUSION The quantification of bowel wall enhancement using the maximal attenuation of an ROI was a reliable and useful method for the diagnosis of intestinal ischemia and showed good correlation with pathology results.

The value of gadoxetic acid-enhanced and diffusion-weighted MRI for prediction of grading of pancreatic neuroendocrine tumors.

Background Parenchyma-preserving resection for the treatment of benign pancreatic neuroendocrine tumors (NETs) has been tried, and preoperative prediction of benign pancreatic NET is important. Recently, diffusion-weighted imaging (DWI) of abdomen magnetic resonance imaging (MRI) has been used to characterize benign and malignant tumors and DWI might be helpful in prediction of benign pancreatic NETs. Purpose To evaluate the value of gadoxetic acid-enhanced MRI and DWI in predicting benign pancreatic NETs for determination of parenchyma-preserving resection. Material and Methods Our ethics committee approved this study with a waiver of informed consent given its retrospective design. We searched radiology and pathology databases from November 2010 to July 2012 to identify patients who underwent surgery for pancreatic NETs (<4 cm). Twenty patients in the benign group and 14 patients in the non-benign group were included in this study. Two radiologists analyzed the morphologic features, signal intensity on MR images including DWI (b = 800), and dynamic enhancement pattern of the tumors with consensus. The tumor-to-parenchyma ratio and tumor apparent diffusion coefficients (ADCs) were quantitatively assessed. Results The benign pancreatic NETs were more often round (7/20, 35%) or ovoid (13/20, 65%) in shape and less hypovascular on the arterial phase (3/20, 15%) than were the non-benign pancreatic NETs (1/14, 7.1% and 5/14, 35.8%; 7/14, 50% respectively; P < 0.05). Main pancreatic duct dilatation by tumors was demonstrated only in non-benign pancreatic NETs (4/14, 28.4%; P = 0.021). ADC values and ratios were significantly different between benign pancreatic NETs (mean, 1.48 × 10−3 mm2/sec, 1.11 ± 0.25, each) and non-benign pancreatic NETs (mean, 1.04 × 10−3 mm2/sec, 0.74 ± 0.13, each) (P < 0.01). Other qualitative and quantitative analyses between benign and non-benign pancreatic NETs were not significantly different (P > 0.05). Conclusion Abdominal MRI with DWI may be useful for differentiating benign pancreatic NETs from non-benign pancreatic NETs, which might be helpful for determination of parenchyma-preserving resection.

Differentiating hepatic abscess from malignant mimickers: Value of diffusion‐weighted imaging with an emphasis on the periphery of the lesion

To evaluate the efficacy of diffusion‐weighted imaging (DWI) in differentiating hepatic abscess from malignant mimickers with an emphasis on periphery of the lesions.

Imaging features of small (≤3 cm) pancreatic solid tumors on gadoxetic-acid-enhanced MR imaging and diffusion-weighted imaging: an initial experience

OBJECTIVE The objective was to determine imaging features that distinguish small (≤3cm) solid pancreatic adenocarcinoma, neuroendocrine tumor (NET) and solid pseudopapillary tumor (SPT) on gadoxetic-acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighed imaging (DWI). MATERIALS AND METHODS Twenty-four adenocarcinomas, 10 NETs and 8 SPTs were retrospectively included. Two radiologists analyzed morphologic features, signal intensity of the tumors on MR images including DWI (b=800) and dynamic enhancement pattern with consensus. Tumor-to-parenchyma ratio and tumor apparent diffusion coefficients (ADCs) were quantitatively assessed. RESULTS All adenocarcinomas had an ill-defined margin and irregular shape, and more frequently had pancreatic duct dilatation compared with other tumors (P<.05). All SPTs and all but one of the adenocarcinomas (95.8%) had no arterial enhancement with progressively increased enhancement, whereas seven NETs (70%) had arterial enhancement with progressively decreased enhancement (P<.01). The mean value of tumor-to-parenchyma ratio on arterial and portal phases was significantly higher for NETs, and the mean value of tumor ADCs was significantly lower for SPTs than for other tumors (P<.05). CONCLUSIONS Gadoxetic-acid-enhanced MRI may aid in differentiation between small adenocarcinomas, NETs and SPTs based on morphologic features with dynamic enhancement pattern in adenocarcinomas, dynamic enhancement pattern with tumor-to-parenchyma ration on arterial and portal phases in NETs, and dynamic enhancement pattern with lower ADC value in SPTs.

Imaging features of subcentimeter hypointense nodules on gadoxetic acid-enhanced hepatobiliary phase MR imaging that progress to hypervascular hepatocellular carcinoma in patients with chronic liver disease.

Background: With the advent of 3-T magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI), many subcentimeter hepatic nodules have been frequently detected in patients with chronic liver disease, and the prediction of subcentimeter nodules that progress to hypervascular hepatocellular carcinoma (HCC) is important. Purpose: To reveal the imaging features of subcentimeter hypointense nodules on gadoxetic acid-enhanced hepatobiliary phase MR images in patients with chronic liver disease that may be related with progression to hypervascular HCC. Material and Methods: This study included 109 patients with 135 subcentimeter hypointense nodules (103 hepatocellular carcinomas [HCCs] and 32 benign nodules) on gadoxetic acid-enhanced hepatobiliary phase. For each subcentimeter nodule, the following imaging features were analyzed: (i) hyperintensity on T2-weighted (T2W) image or DWI; (ii) arterial hypervascularization; and (iii) hypointensity on a portal or late phase. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of those imaging features for predicting subcentimeter nodules that progressed to hypervascular HCC were evaluated. Volume doubling time (VDT) of subcentimeter nodules that progressed to hypervascular HCC was compared to that of growing benign nodules. Results: Arterial hypervascularization with washout yielded the highest specificity (90.6%) and PPV (95.4%) for prediction of subcentimeter nodules that progressed to hypervascular HCC. Combining hyperintensity on T2W image or DWI and arterial hypervascularization with washout did not raise the specificity (90.6%) for prediction of subcentimeter nodules that progressed to hypervascular HCC. Mean VDT (112.2 ± 106.3 days) of subcentimeter nodules that progressed to hypervascular HCC during follow-up was significantly shorter than those of benign subcentimeter nodules (1258 ± 766.5 days, P < 0.001). Conclusion: Arterial hypervascularization with washout in subcentimeter hypointense nodules on gadoxetic acid-enhanced hepatobiliary phase in patients with chronic liver disease is strongly related with progression to hypervascular HCC.

The rates and CT patterns of locoregional recurrence after resection surgery of lung cancer: Correlation with histopathology and tumor staging

The purpose of our study was to assess the rates and CT patterns of locoregional recurrence after resection surgery of lung cancers according to histopathology and tumor staging. Three hundred and seventy nine patients who underwent lung resection surgery due to lung cancer in a recent 6 year period were followed up with CT (at 3, 6, 12, 18, 24 months, and then annually after surgery) for evaluation of locoregional tumor recurrence (analysis of hilar or mediastinal lymph nodes and surgical margin including bronchial stump, pleura, and chest wall). The recurrence rates and CT patterns were compared in terms of underlying histopathology and tumor staging. Of 379 patients, 75 (20%) patients had locoregional recurrences. The recurrence rates were higher in squamous cell carcinoma (39/190, 21%) than adenocarcinoma (24/140, 17%) (P = 0.012). The patterns of recurrence in 75 patients were hilar-mediastinal lymph node enlargement (n = 39, 52%), ipsilateral pleural lesion (n = 24, 32%), chest wall lesion (n = 13, 17%), bronchial stump lesion (n = 8, 11%), and bronchial extension including the trachea (n = 3, 4%). Bronchial stump recurrence was seen only in squamous cell carcinoma. Bronchioloalveolar carcinoma did not show any evidence of locoregional recurrence. Pleural (P = 0.0016) and mediastinal nodal (P = 0.001) recurrence, respectively, were more common in N2 than N0 cancers. Chest wall recurrence rates were higher with higher T staging (P < 0.001). The locoregional recurrence of lung cancer occurs in about one fifth of patients who undergo curative resection and is more common in squamous cell carcinoma than in adenocarcinoma. Recurrent patterns are diverse and different according to histopathologic type and pathologic staging of lung cancer.

Added Value of Diffusion-weighted MR Imaging in the Diagnosis of Ampullary Carcinoma

PURPOSE To evaluate the added value of diffusion-weighted magnetic resonance (MR) imaging in diagnostic performance of conventional MR imaging for diagnosis of ampullary carcinoma. MATERIALS AND METHODS This retrospective study was institutional review board approved, and informed consent was waived. Twenty-three patients with malignant ampullary obstruction and 39 patients with benign ampullary obstruction were included. Qualitative (signal intensity and enhancement pattern) and quantitative (apparent diffusion coefficient [ADC]) analyses were conducted for visible or expected locations of duodenal papillae. Two observers independently reviewed conventional MR images and subsequently reviewed combined conventional and diffusion-weighted MR images. A five-point scale for likelihood of ampullary carcinoma was used. Fisher exact test and Mann-Whitney U test were used for comparing groups, and diagnostic performance (receiver operating characteristic [ROC] curve analysis), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were evaluated. RESULTS Visible or expected duodenal papillae in benign group showed isointensity (27-38 of 39, 69%-97%) and similar enhancement pattern (27 of 39, 69%) to that of normal duodenal wall more frequently than in malignant group (seven to 18 of 23 [30%-78%] and three of 23 [13%], respectively) on conventional MR images (P < .05). On diffusion-weighted images, 21 of 23 (91%) ampullary carcinomas showed hyperintensity, whereas all benign cases showed isointensity compared with normal duodenal wall (P < .001). Mean ADC of ampullary carcinomas (1.23 × 10(-3) mm(2)/sec) was significantly lower than that of benign group (1.69 × 10(-3) mm(2)/sec) (P < .001). Diagnostic performance (area under ROC curve [Az]) of both observers improved significantly after additional review of diffusion-weighted images; Az improved from 0.923 to 0.992 (P = .029) for observer 1 and from 0.910 to 0.992 (P = .025) for observer 2. In addition, diagnostic accuracy, sensitivity, specificity, PPV, and NPV of combined conventional and diffusion-weighted MR images were higher than those of conventional MR images alone. CONCLUSION Addition of diffusion-weighted imaging to conventional MR imaging improves detection of ampullary carcinoma when compared with conventional MR imaging alone.