Factors affecting the ability of abdominal ultrasonography to detect focal pancreatic lesions identified using endoscopic ultrasonography.

PURPOSE: This study was conducted to determine which factors influence the ability of abdominal ultrasonography (US) to detect focal pancreatic lesions identified using endoscopic ultrasonography (EUS). METHODS: In this study, 338 consecutive patients with focal pancreatic lesions (cyst, n=253; adenocarcinoma, n=54; pancreatic neuroendocrine tumor, n=24; solid pseudopapillary neoplasm, n=4; intrapancreatic accessory spleen, n=1; metastasis, n=1; and lymphoma, n=1) detected by EUS who underwent US were enrolled. We reviewed their radiologic reports and assessed the presence or absence of a focal lesion, the multiplicity of the lesions, and their size and location on US. We evaluated how these parameters differed depending on whether the lesion was solid or cystic. Univariate and multivariate logistic regression analysis were performed. RESULTS: The overall detection rate of focal pancreatic lesions by US was 61.5% (208 of 338). Using US, the detection rate of cystic lesions was 58.5% (148 of 253), while that of solid lesions was 70.6% (60 of 85). In the univariate analysis, location in the neck or body, solid characteristics, and a relatively large size (15.50±10.08 mm vs. 23.09±12.93 mm) were associated with a significantly higher detection rate (P<0.001, P=0.047, and P<0.001, respectively). In the multivariate analysis, location in the neck or body (odds ratio [OR], 3.238; 95% confidence interval [CI], 1.926 to 5.443; P<0.001) and size (OR, 1.070; 95% CI, 1.044 to 1.096; P<0.001) were proven to be significant predictors of detectability (P<0.001). CONCLUSION: US is useful for detecting focal pancreatic lesions, especially when they are located in the neck or body and are relatively large.

Diagnostic performance and imaging features for predicting the malignant potential of intraductal papillary mucinous neoplasm of the pancreas: a comparison of EUS, contrast-enhanced CT and MRI.

PURPOSE: To compare diagnostic performance for prediction of malignant potential in IPMNs between EUS, contrast-enhanced CT and MRI. MATERIALS AND METHODS: 76 patients with IPMN (benign = 37, malignant = 39) underwent EUS, contrast-enhanced CT, and MRI. EUS was analyzed based on formal reports and contrast-enhanced CT and MRI were retrospectively analyzed by two radiologists according to the consensus guidelines 2012. Diagnostic performance and imaging features of malignant IPMNs were analyzed using ROC analysis and multivariate analyses. RESULTS: Diagnostic performance of contrast-enhanced CT (AUC = 0.792 in R1, 0.830 in R2), MRI (AUC = 0.742 in R1, 0.776 in R2), and EUS (AUC = 0.733) for predicting malignant IPMNs were comparable without significant difference (p > 0.05). In multivariable analysis, enhancing solid component in contrast-enhanced CT and MRI and mural nodule in EUS (OR 1.8 in CT, 1.36 in MRI, 1.47 in EUS), MPD diameter ≥ 10 mm (OR 1.3 in CT, 1.4 in MRI, 1.66 in EUS), MPD diameter of 5-9 mm (OR 1.23 in CT, 1.31 in MRI), and thickened septa or wall (OR 1.3 in CT and MRI) were significant variables (p < 0.05). Interobserver agreement of thickened cyst septa or wall (k = 0.579-0.617) and abrupt caliber change of MPD (k = 0.689-0.788) was lower than other variables (k > 0.80). CONCLUSION: Diagnostic performance of contrast-enhanced CT, MRI, and EUS for predicting malignant IPMNs was comparable with each modalities without significant difference.

Pancreatic neuroendocrine tumour (PNET): Staging accuracy of MDCT and its diagnostic performance for the differentiation of PNET with uncommon CT findings from pancreatic adenocarcinoma.

PURPOSE: To investigate staging accuracy of multidetector CT (MDCT) for pancreatic neuroendocrine tumour (PNET) and diagnostic performance for differentiation of PNET from pancreatic adenocarcinoma. MATERIAL AND METHODS: We included 109 patients with surgically proven PNET (NETG1 = 66, NETG2 = 31, NEC = 12) who underwent MDCT. Two reviewers assessed stage and presence of predefined CT findings. We analysed the relationship between CT findings and tumour grade. Using PNETs with uncommon findings, we also estimated the possibility of PNET or adenocarcinoma. RESULTS: Accuracy for T stage was 85-88% and N-metastasis was 83-89%. Common findings included well circumscribed, homogeneously enhanced, hypervascular mass, common in lower grade tumours (p < 0.05). Uncommon findings included ill-defined, heterogeneously enhanced, hypovascular mass and duct dilation, common in higher grade tumours (p < 0.05). Using 31 PNETs with uncommon findings, diagnostic performance for differentiation from adenocarcinoma was 0.760-0.806. Duct dilatation was an independent predictor for adenocarcinoma (Exp(B) = 4.569). PNETs with uncommon findings were associated with significantly worse survival versus PNET with common findings (62.7 vs. 95.7 months, p < 0.001). CONCLUSION: MDCT is useful for preoperative evaluation of PNET; it not only accurately depicts the tumour stage but also prediction of tumour grade, because uncommon findings were more common in higher grade tumours. KEY POINTS: • CT accurately depicts the T stage and node metastasis of PNET. • Uncommon findings were more common in higher grade tumours. • CT information may be beneficial for optimal therapeutic planning.

High-resolution sonography for distinguishing neoplastic gallbladder polyps and staging gallbladder cancer.

OBJECTIVE. The purposes of this study were to compare staging accuracy of high-resolution sonography (HRUS) with combined low- and high-MHz transducers with that of conventional sonography for gallbladder cancer and to investigate the differences in the imaging findings of neoplastic and nonneoplastic gallbladder polyps. MATERIALS AND METHODS. Our study included 37 surgically proven gallbladder cancer (T1a = 7, T1b = 2, T2 = 22, T3 = 6), including 15 malignant neoplastic polyps and 73 surgically proven polyps (neoplastic = 31, nonneoplastic = 42) that underwent HRUS and conventional transabdominal sonography. Two radiologists assessed T-category and predefined polyp findings on HRUS and conventional transabdominal sonography. Statistical analyses were performed using chi-square and McNemar tests. RESULTS. The diagnostic accuracy for the T category was T1a = 92-95%, T1b = 89-95%, T2 = 78-86%, and T3 = 84-89%, all with good agreement (κ = 0.642) using HRUS. The diagnostic accuracy for differentiating T1 from T2 or greater than T2 was 92% and 89% on HRUS and 65% and 70% with conventional transabdominal sonography. Statistically common findings for neoplastic polyps included size greater than 1 cm, single lobular surface, vascular core, hypoechoic polyp, and hypoechoic foci (p < 0.05). The value of HRUS in the differential diagnosis of a gallbladder polyp was more clearly depicted internal echo foci than conventional transabdominal sonography (39 vs 21). A polyp size greater than 1 cm was independently associated with a neoplastic polyp (odds ratio = 7.5, p = 0.02). The AUC of a polyp size greater than 1 cm was 0.877. The sensitivity and specificity were 66.67% and 89.13%, respectively. CONCLUSION. HRUS is a simple method that enables accurate T categorization of gallbladder carcinoma. It provides high-resolution images of gallbladder polyps and may have a role in stratifying the risk for malignancy.

Diagnostic performance of MDCT for predicting important prognostic factors in pancreatic cancer.

OBJECTIVES: Tumor stage, node metastasis, tumor size, vascular invasion, and perineural invasion are the most important prognostic factors that might be determined by preoperative multidetector computed tomography (MDCT) in pancreatic cancer. The purpose of our study is to investigate diagnostic accuracy of MDCT for determining these prognostic factors. METHODS: For 6 years, 111 patients with surgically resected pancreatic cancer underwent preoperative MDCT. Two radiologists retrospectively assessed tumor stage, node metastasis, tumor size, and vascular invasion. They also graded perineural invasion using a 3-point scale focused on 5 routes. Statistical analyses were performed using the receiver operating characteristic analysis, McNemar test, and paired t test. RESULTS: Statistically, tumor size on specimens (3.4 ± 1.46 cm) is larger than tumor size on MDCT (3.2 ± 1.41 cm; P = 0.001). The diagnostic accuracy rates for tumor stage were 82.9% and 77.5%, with moderate agreement (κ = 0.732). The accuracy rates for node metastasis were 59.5% and 55.0%, with fair agreement (κ = 0.597). The diagnostic accuracy rates for vascular invasion were 94% and 92%. The areas under the curve for perineural invasion were 0.733 and 0.66 (P = 0.069), with moderate agreement (κ = 0.77). CONCLUSIONS: Multidetector computed tomography is very useful for the preoperative evaluation of tumor stage, perineural invasion, and vascular invasion of pancreatic cancer, but it has limited evaluation of node metastasis and tumor size.

Intraductal papillary mucinous neoplasms with associated invasive carcinoma of the pancreas: imaging findings and diagnostic performance of MDCT for prediction of prognostic factors.

OBJECTIVE: The purpose of this study was to assess the diagnostic accuracy of MDCT for determining the prognostic factors, including the T category, lymph node metastasis, tumor size, and perineural invasion, in surgically proven intraductal papillary mucinous neoplasms (IPMNs) with an associated invasive carcinoma (IPMC) and to investigate the imaging findings. MATERIALS AND METHODS: Our study group consisted of 38 patients with surgically proven IPMC who underwent preoperative dynamic CT. Two radiologists retrospectively assessed the morphologic type of IPMN, size of the cyst, size of the main pancreatic duct, and presence or absence of mural nodules. The radiologists also assessed the T category, lymph node metastasis, and perineural invasion. They graded the perineural invasion using a 3-point scale as follows: 1, normal; 2, streaky and strandlike structure in fat tissue as well as a fine, reticular pattern; and 3, irregular masses adjacent to the lesions. Statistical analyses were performed using receiver operating characteristic analysis, the McNemar test, and Fisher exact test. Kappa statistics were used to determine interobserver agreement. RESULTS: The morphologic types of IPMC included the main-duct type (n=11, 29%), combined type (n=18, 47%), and branch-duct type (n=9, 24%). The diagnostic accuracy for the T category was 73.7% (n=28) and 68.4% (n=26) and for the lymph node metastasis was 68.4% (n=26) and 76.3% (n=29), respectively, for the two readers, with moderate interobserver agreement (κ=0.636 and 0.708). The areas under the receiver operating characteristic curve for perineural invasion were 0.868 and 0.821. The sensitivity, specificity, and positive predictive value were 100%, 71.4%, 55.5%, and 90%, 71.4%, 52.9%, respectively. Interobserver agreement was moderate (κ=0.659). The tumor size seen on CT was not statistically different from the tumor size determined on pathology (3.9±[SD] 2.7 cm vs 3.8±2.1 cm, p=0.582). The main duct size was 11.5+6.2 mm. Mural nodules were detected in 74% (n=28) of our study patients. CONCLUSION: CT might be useful for preoperatively evaluating the T category, lymph node metastasis, tumor size, and perineural invasion of IPMC. Main pancreatic duct dilatation and the presence of mural nodules are common findings of IPMC.

Staging accuracy of MR for pancreatic neuroendocrine tumor and imaging findings according to the tumor grade.

PURPOSE: To investigate staging accuracy of MR for pancreatic neuroendocrine neoplasms (PNETs) and imaging findings according to the tumor grade. MATERIALS AND METHODS: Our study consisted of 39 patients with PNET G1 (n = 24), PNET G2 (n = 12), and pancreatic neuroendocrine carcinoma (PNEC) (n = 3). All underwent preoperative MRI. Two radiologists retrospectively reviewed MR findings including tumor margin, SI on T2WI, enhancement patterns, degenerative change, duct dilation, and ADC value. They also assessed T-stage, N-stage, and tumor size. Statistical analyses were performed using Chi square tests, ROC analysis, and Fisher's exact test. RESULTS: Specific findings for PNEC or PNET G2 were ill-defined borders (P = 0.001) and hypo-SI on venous- and delayed-phase (P = 0.016). ADC value showed significant difference between PNET G1 and G2 (P = 0.007). The Az of ADC value for differentiating PNET G1 from G2 was 0.743. Sensitivity and specificity were 70% and 86%. Accuracy for T-staging was 77% (n = 30) and 85% (n = 33), and for N-staging was 92% (n = 36) and 87% (n = 34) with moderate agreement. T-stage showed significant difference according to tumor grade (P < 0.001), although there was no significant difference in tumor size or N-stage. CONCLUSION: Ill-defined borders and hypo-SI on venous- and delayed-phase imaging are common findings of higher grade PNET, and ADC value is helpful for differentiating PNET G1 from G2. MR is useful for preoperative evaluation of T-, N-stage. Tumor size of PNET and T-stage showed significant difference according to tumor grade.

Diagnostic performance of MRI and EUS in the differentiation of benign from malignant pancreatic cyst and cyst communication with the main duct.

PURPOSE: To assess the diagnostic ability of MRI and EUS for differentiating benign from malignant pancreatic cyst focusing on cyst communication with pancreatic duct. MATERIALS AND METHODS: During 44 months, we performed MRI on 65 pancreatic cysts. Among them, 36 patients had confirmed cyst communication with duct by ERCP or surgery and 39 patients underwent EUS. Fifty-one had proven by surgery or aspiration. Among them, 36 had confirmed malignant cysts. Two radiologists independently graded cyst communication with duct and the likelihood of malignancy. When the readers' interpretations differed, third opinion was obtained. They also measured the size of cyst and main duct. The diagnostic performance was analyzed using the ROC curve. The Mann-Whitney U test and κ statistics were used to determine interobserver agreement. RESULTS: The Az of MRI and EUS for determining diagnostic performance regarding the cyst communication with duct, were 0.931 and 0.930, without statistically difference (p=0.6). Interobserver agreement was excellent (κ=0.81) on MRI and substantial (κ=0.69) on EUS. The Az of MRI and EUS for assessing diagnostic performance to differentiate malignant from benign cyst, was 0.902 and 0.923, without statistically difference (p=0.587). Interobserver agreement was excellent (κ=0.81) on MRI and moderate (κ=0.47) on EUS. The mean cyst size (3.98 cm+2.74: 3.17 cm+1.26, p=0.327) and the duct size (5.20 mm+3.22: 4.39 mm+4.12, p=0.227) showed no statistically difference between malignant and benign cysts. CONCLUSION: MRI and EUS can accurately assess pancreatic cyst communication with duct and are very useful for obtaining a differential diagnosis of malignant cyst versus benign pancreatic cyst.

Malignant versus benign hepatic masses in patients with recurrent pyogenic cholangitis: MR differential diagnosis.

PURPOSE: To assess MR findings and diagnostic performance for differentiating malignant from benign hepatic masses in recurrent pyogenic cholangitis (RPC). MATERIALS AND METHODS: During a recent 6-year period, we performed MRI in 352 patients with RPC. Among them, 58 had confirmed hepatic masses; cholangiocarcinoma (n = 15), abscess (n = 37), inflammatory pseudotumor (n = 3), biloma (n = 3). Two radiologists assessed MR findings including enhancement patterns, intratumoral appearance, peritumoral changes, mass location, and multiplicity. They also graded the malignancy using common MR findings. The receiver operating characteristic analysis and Chi-square test were used. The κ statistics was used to determine interobserver agreement. RESULTS: The common findings for cholangiocarcinoma were thin and lobulated enhancement at the periphery (n = 8, 53%, P < 0.05); ill-defined enhancement (n = 7, 47%, P < 0.05); slightly high signal on T2 (n = 13, 87%, P < 0.05); mass located in the same lobe of atrophy (n = 11, 73%, P < 0.05) and portal vein thrombosis (n = 15, 100%, P < 0.05). The common findings for benign mass were target-like enhancement (n = 36, 84%, P < 0.05); cluster appearance (n = 15, 35%, P < 0.05); central, fluid-like space (n = 29, 67%, P < 0.05); peritumoral regional high signal on T2 (n = 32, 74%, P < 0.05); multiplicity(n = 21, 49%, P < 0.05). Interobserver agreement was excellent (κ = 0.81-1.000). Area under the curve (Az) for differentiating malignant masses was 0.989, sensitivity was 95.3%, and specificity was 95.3%. There was good interobserver agreement (κ = 0.74). CONCLUSION: MR imaging is very useful for differential diagnosis of malignant vs. benign hepatic masses in patients with RPC.

Gastric cancer detection using MDCT compared with 2D axial CT: diagnostic accuracy of three different reconstruction techniques.

PURPOSE: To assess the diagnostic accuracy of different reconstruction techniques using MDCT for gastric cancer detection compared with 2D axial CT. MATERIALS AND METHODS: During 7 months, we performed CT examinations of 104 consecutive patients with gastric cancer and of a control group composed of 35 patients without gastric disease. All gastric cancer was pathologically proven by endoscopy and surgery. Among 104 patients with gastric cancer, 63 patients had early gastric cancer (EGC). Two radiologists retrospectively and independently interpreted the axial CT and three different reconstruction techniques including multiplanar reformation (MPR), transparent imaging (TI), and virtual gastroscopy (VG), using a commercially available, 3D workstation. They graded the presence or absence of gastric cancer in each image sets using a five-point scale and, if present, they assessed its location. Diagnostic accuracy was compared using the area under the receiver operating characteristic curve (Az) for both gastric cancer and only EGC. Sensitivity and specificity were also calculated for each image technique. The k statistics were used to determine inter-observer agreement. RESULTS: The diagnostic accuracy for overall gastric cancer detection for each of the image sets was as follows: 2D axial CT (Az = 0.858); MPR (Az = 0.879); TI (Az = 0.873); and VG (Az = 0.928). VG had significantly better performance than 2D axial CT (p = 0.016). The sensitivity and specificity were as follows: 76.7% and 82.9% in axial CT; 79.6% and 85.7% in MPR; 91.3% and 80% in TI; and 95.1% and 74.3% in VG. In EGC, the diagnostic performance for its detection was as follows: axial CT (Az = 0.777); MPR (Az = 0.811); TI (Az = 0.825); and VG (Az = 0.896). VG had significantly better performance than both 2D axial CT (P = 0.006) and MRP (P = 0.038). The sensitivity and specificity were as follows: 62.9% and 82.9% in axial CT; 67.7% and 85.7% in MPR; 85.5% and 80% in TI; and 91.9% and 74.3% in VG. The inter-observer agreement showed substantial agreement (κ = 0.67-0.75). CONCLUSION: Among the different reconstruction techniques, VG accurately detects gastric cancer and is especially useful for EGC compared with 2D axial CT.

Intraductal papillary mucinous neoplasm of the pancreas: differentiate from chronic pancreatits by MR imaging.

PURPOSE: To evaluate the differentiating factors for intraductal papillary mucinous neoplasm of the pancreas and chronic pancreatitis as determined by MR imaging. MATERIALS AND METHODS: During a three-year period, we performed MR imaging on 33, consecutive patients with IPMN and on 41 patients with chronic pancreatitis. All IPMNs were confirmed by surgery. Two radiologists retrospectively analyzed the ductal change, the cyst shape, CBD dilatation, lymphadenopathy, and parenchymal change. The sensitivity and specificity were calculated for each MRI findings using the Chi square test. Statistically significant MR findings were further analyzed using multivariate logistic regression analysis. The diagnostic performance was evaluated according to the area under the receiver operating characteristic curve (A(z)) using specific MRI findings. Simple κ statistics were used to evaluate the inter-observer reliability. RESULTS: Statistically specific findings for IPMN compared with those for chronic pancreatitis, were duct dilatation without stricture (specificity=95.1%, sensitivity=75.8%, p<0.0001), bulging ampulla (specificity=97.6%, sensitivity=30.3%, p<0.0001), nodule in a duct (specificity=100%, sensitivity=15.2%, p<0.0004), grape-like cyst shape (specificity=97.6%, sensitivity=78.8%, p<0.0001), and nodule in a cyst (specificity=100%, sensitivity=24.2%, p<0.0001). Statistically specific findings for chronic pancreatitis compared with those for IPMN, were duct dilatation with strictures (specificity=93.9%, sensitivity=95.1%, p<0.0001), the presence of a stone (specificity=97.0%, sensitivity=56.1%, p<0.0001), and a unilocular cyst shape (specificity=93.9%, sensitivity=34.1%, p<0.0004). Duct dilatation without stricture and a grape-like cyst shape were independently associated with the IPMN. Duct dilatation with strictures was independently associated with the chronic pancreatitis. Interobserver agreement was good to excellent for each finding (κ=0.762-1.000). CONCLUSION: Highly specific findings for IPMN include duct dilatation without stricture, bulging ampulla, nodule in a duct, grape-like cyst shape, and nodule in a cyst. MRI is very useful for differentiating IPMN from chronic pancreatitis using these specific findings.

Clinical usefulness of free-breathing navigator-triggered 3D MRCP in non-cooperative patients: comparison with conventional breath-hold 2D MRCP.

PURPOSE: To assess the clinical usefulness of free-breathing 3D MRCP in non-cooperative patients compared conventional breath-hold 2D MRCP. MATERIALS AND METHODS: We performed FB navigator-triggered 3D MRCP using prospective acquisition correction and BH 2D MRCP in 48 consecutive, non-cooperative patients among 772 patients. Thirteen patients had malignant obstruction. Two radiologists independently graded the likelihood of a malignant obstruction, the overall image quality, and the visibility of ten, individual anatomic segments of both the biliary and pancreatic duct in each sequence. The area under the ROC curve and the repeated measures analyses of variance with multiple comparisons were used for the comparison. The κ statistics were used for interobserver agreement. RESULT: The diagnostic performance for detecting malignancy was significantly higher on FB MRCP (A(z)=0.962) than on either BH SS-RARE (A(z)=0.820, P<0.0185) or MS-HASTE MRCP (A(z)=0.816, P<0.0067). Interobserver agreement was excellent for FB MRCP (κ=0.889) and fair for both BH SS-RARE (κ=0.578) and MS-HASTE MRCP (κ=0.49). FB MRCP had a significantly higher technical quality than BH MRCP (P<0.001). FB MRCP was seen to have statistically better visibility of peripheral IHD, right main IHD, CHD, cystic duct, and CBD than BH MRCP (P<0.001). FB MRCP and BH SS-RARE MRCP had statistically better visibility of both the left main IHD and pancreatic duct than did BH MS-HASTE MRCP (P<0.001). CONCLUSION: FB 3D MRCP is useful for non-cooperative patients in whom conventional BH 2D methods cannot be used successfully.

Assessment of acute cholangitis by MR imaging.

PURPOSE: The purpose of this study is to assess the common MRI findings of acute cholangitis compared with those of non-acute cholangitis. MATERIALS AND METHODS: During a 31-month period, we performed MRCP and contrast-enhanced MRI on 173 patients with biliary abnormalities including duct dilatation or stricture. The causes of the biliary abnormalities included biliary stone disease (n=85), cholangiocarcinoma (n=47), periampullary cancer (n=20), GB cancer (n=4), and others (n=17). Among 173 patients, 66 consecutive patients were confirmed with acute cholangitis diagnosed according to the Tokyo guideline, and 107 patients were confirmed as having non-acute cholangitis. Two radiologists retrospectively and independently accessed the MR findings, including the cause of biliary abnormality, increased periductal signal intensity on T2-weighted images, the transient periductal signal difference, and the presence of abscess, thrombosis, and ragged duct. They also measured the dilated duct and the thickened wall. The Student t-test and the Pearson chi-square were used. The κ statistics were used to determine interobserver agreement. Logistic regression was used to identify the MR findings that predicted acute cholangitis. RESULTS: MRI correctly accessed the cause of biliary abnormality in 163 patients (94%). The statistically common findings for acute cholangitis were as follows: increased periductal signal intensity on T2-weighted imaging (n=26, 39%, p<0.05); transient periductal signal difference (n=31, 47%, p<0.05); abscess (n=18, 27%, p<0.05); thrombosis (n=12, 18%, p<0.05); and ragged duct (n=11, 17%, p<0.05). Interobserver agreement was good to excellent for each finding (κ=0.74-0.97). The wall thickness showed a statistically significant difference between the acute cholangitis and the non-acute cholangitis group (2.65 mm:2.32 mm, p<0.05), however, there was no significant difference in duct dilatation in the two groups. The periductal transient attenuation difference was an independent predictor of acute cholangitis (Exp (B)=6.389, p=0.018). CONCLUSION: MRI accurately assesses the cause of biliary abnormality in patients with cholangitis. Using statistically common MR findings for acute cholangitis, MR imaging is very successful in predicting acute cholangitis.

Small-bowel angioedema during screening computed tomography due to intravenous contrast material.

We describe patients with isolated small-bowel angioedema caused by allergic reactions to intravenous contrast media. Computed tomography (CT) revealed circumferential thickening of the walls of the duodenum or jejunum. Follow-up small-bowel follow-through, small-bowel endoscopy, and CT showed normalized small-bowel loops. Transient findings of circumferential thickening of the small-bowel walls on CT suggest isolated small-bowel angioedema.

Differentiation between biliary cystic neoplasms and simple cysts of the liver: accuracy of CT.

OBJECTIVE: The objective of our study was to determine significant CT findings for the differentiation of biliary cystic neoplasms from simple hepatic cysts and to assess whether radiologists' performance for the differentiation is improved with the knowledge of significant CT criteria. MATERIALS AND METHODS: Review of surgical and pathologic records identified 25 patients with pathologically proven biliary cystic neoplasms (biliary cystadenomas [n = 8], biliary cystadenocarcinomas [n = 4]) or simple cysts [n = 13]). Two radiologists retrospectively reviewed CT images in consensus for the location, size, and outer margin of the lesion and for the presence of an internal septum, upstream bile duct dilatation, a transient hepatic attenuation difference (THAD), calcifications, a mural nodule, three or more other cysts, and a thick septum or outer wall. Individual CT findings considered significant for the differentiation were determined using univariate statistical analyses. Then, two successive review sessions for the differentiation between the two disease entities were independently performed by two other reviewers using a 4-point confidence scale. At the first session, no information was provided to reviewers for differentiation. At the second session, however, the reviewers were told of the results of univariate analyses. Radiologists' performance was evaluated using pairwise comparison of receiver operating characteristic (ROC) curves. RESULTS: The mean size of biliary cystic neoplasms (9.5 cm) was not significantly different from that of simple cysts (11.2 cm). The presence of upstream bile duct dilatation achieved the highest specificity (100%) for the differentiation of biliary cystic neoplasms from simple cysts, followed by THAD (84.6%), lesion location at the left lobe (76.9%), and coexistence of fewer than three other cysts (69.2%). The area under the curve of reviewers 1 and 2 significantly increased from 0.686 and 0.654 to 0.997 and 0.936, respectively, when the reviewers knew the information about the significant CT criteria (p = 0.003 and p = 0.008, respectively). CONCLUSION: Upstream bile duct dilatation, lesion location at the left hepatic lobe, fewer than three coexistent cysts, and THAD were found to be highly suggestive CT findings for the differentiation of biliary cystic neoplasms from simple hepatic cysts. Radiologists' performance was significantly improved with the knowledge of these highly suggestive CT criteria.

Accuracy of MRI for predicting the circumferential resection margin, mesorectal fascia invasion, and tumor response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer.

PURPOSE: To evaluate the diagnostic accuracy of MRI for predicting the circumferential resection margin (CRM), mesorectal fascia (MRF) invasion, and the tumor response to neoadjuvant chemoradiotherapy (CRT) for locally advanced rectal cancer. MATERIALS AND METHODS: Sixty-five consecutive patients with locally advanced rectal cancer (> or =T3 or lymph node-positive) who underwent neoadjuvant CRT and subsequent surgery were enrolled in this retrospective study. Two blinded radiologists independently reviewed both the pre- and post-CRT rectal MR images and measured the post-CRT CRM; they recorded their confidence level with respect to the MRF invasion and tumor response using a 5-point scale. The diagnostic accuracy of each reviewer was calculated using receiver operating characteristic curve (ROC) analysis. RESULTS: The measured CRM was not significantly different from the reference standard (mean difference, -1.4 mm; 95% limits of agreement, -8.3-5.4 mm; interclass correlation coefficient, 0.82). The diagnostic accuracy (A(z)) for determining MRF invasion was 0.890 for reviewer 1 (95% confidence interval [CI], 0.788-0.954) and 0.829 for reviewer 2 (95% CI, 0.715-0.911). The A(z) for predicting complete or near-complete regression was 0.791 for reviewer 1 (95% CI, 0.672-0.882) and 0.735 for reviewer 2 (95% CI, 0.611-0.837). CONCLUSION: MRI provides accurate information regarding the CRM of locally advanced rectal cancer after neoadjuvant CRT; it also shows relatively high accuracy for predicting MRF invasion and moderate accuracy for assessing tumor response.

Effects of spatial resolution and tube current on computer-aided detection of polyps on CT colonographic images: phantom study.

PURPOSE: To prospectively evaluate the effects of z-axis spatial resolution and tube current on the sensitivity of a commercially available computed tomographic (CT) colonography computer-aided diagnosis (CAD) system for polyp detection by using pig colon phantoms. MATERIALS AND METHODS: Ninety-six polyps were created and analyzed in 14 pig colon phantoms. CT colonography was performed by using a 16-detector CT scanner at 0.75-mm collimation; 10, 50, 100, and 160 mAs; and a pitch of 1.5. At each milliampere-second setting, the CT images were reconstructed with a section thickness (ST) of 1.5 mm and a reconstruction increment (RI) of 1.3 mm. To evaluate the effect of z-axis spatial resolution, CT images were also reconstructed at 100 mAs with various SI and RI combinations (respectively: 1.0 and 0.7 mm, 3.0 and 2.0 mm, 3.0 and 3.0 mm, 5.0 and 5.0 mm). The phantom data were then analyzed by using a CAD program. CAD performance with different CT parameters was calculated and compared in terms of per-polyp sensitivity and number of false-positive (FP) findings per data set. RESULTS: At a constant tube current of 100 mAs, the polyp detection rate was significantly higher in data sets obtained with SI and RI combinations of 1.0 and 0.7 mm, respectively (81% [78/96]), and 1.5 and 1.3 mm, respectively (75% [72/96]), than in those obtained with the three thicker ST-RI settings (27% [26/96] to 64% [61/96]) (P < .01). A similar trend was observed, regardless of polyp size or morphology. However, the number of FP findings at the 1.0 mm and 0.7 mm setting (8.9 per phantom) was also significantly greater than that at the thicker ST-RI settings (4.0-6.1 per phantom) (P < .05). At a constant z-axis spatial resolution (1.5-mm ST, 1.3-mm RI), CAD polyp detection rate and number of FP findings per phantom remained nearly constant-close to 78% (75/96) and 6.1, respectively-at various tube current settings. CONCLUSION: CAD performance in polyp detection at CT colonography is highly dependent on z-axis spatial resolution. However, tube current is not an influencing factor in CAD performance at a given z-axis spatial resolution. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/2482071025/DC1.

The efficacy of intravenous contrast-enhanced 16-raw multidetector CT colonography for detecting patients with colorectal polyps in an asymptomatic population in Korea.

PURPOSE: The purpose of this study is to compare the sensitivity of computed tomography (CT) colonography (CTC) with that of colonoscopy for detecting patients with colorectal polyps in an asymptomatic screening population in Korea, thus to evaluate a possibility, whether CTC could be used as a screening tool for colorectal polyps. METHODS: A total of 241 asymptomatic adults underwent intravenous contrast-enhanced CTC and colonoscopy successively on the same day. Bowel preparation was performed by 4 L of polyethylene glycol (n=172) or 90 mL of sodium phosphate (n=69). The CTC findings were released to the colonoscopists after the first examination of each segment, a procedure known as segmental unblinded colonoscopy, and were used as the reference standard. The diagnostic performance of CTC for colorectal polyps was calculated. RESULTS: The per-patient sensitivities of CTC were 68.5% (37/54) and 86.7% (13/15) for polyp > or = 6 and > or = 10 mm, inferior to those of colonoscopy, 92.6% (50/54) and 100% (15/15), respectively. The per-polyp sensitivities of CTC were 60.4% (61/101) and 72.7% (16/22) for polyp > or = 6 and > or = 10 mm, respectively. The low sensitivity of CTC was related with flat morphology. CTC detected only 37.5% (9/24) of flat polyps > or = 6 mm. Bowel preparation by sodium phosphate further decreased the positive predictive value and specificity than by polyethylene glycol. CONCLUSIONS: Screening by CTC with asymptomatic population was not promising in Korea despite using advanced CT technology (16-row detector). Bowel preparation was one of the key determinants of the specificity of CTC.