Hyuk Jung Kim

Preoperative evaluation of bile duct cancer: MRI combined with MR cholangiopancreatography versus MDCT with direct cholangiography.

OBJECTIVEnThe purpose of this study was to compare the performance of MRI combined with MR cholangiopancreatography (MRCP) with that of MDCT combined with direct cholangiography in the evaluation of the tumor extent and resectability of bile duct cancer with surgical and pathologic findings as the reference standard.nnnMATERIALS AND METHODSnFrom January 2003 to March 2006, 27 patients (18 men, nine women; mean age, 60.8 years; range, 43-80 years) with surgically proven hilar cholangiocarcinoma or common bile duct (CBD) cancer who had undergone preoperative 2D and 3D MRCP with gadolinium-enhanced MRI and triple-phase MDCT with direct cholangiography (ERCP or percutaneous transhepatic cholangiography) were included in this retrospective study. Two experienced radiologists independently reviewed the two image sets. These readers evaluated the longitudinal extent of the tumor for involvement of the secondary confluence of both intrahepatic ducts and the intrapancreatic CBD, vascular involvement of the tumor, lymph node metastasis, and tumor resectability. The radiologists performance was evaluated by calculation of sensitivity, specificity, and overall accuracy. Correlation was made with the resected specimens or findings at surgical exploration.nnnRESULTSnFor each reviewer, the overall accuracy rates for predicting involvement of the bilateral secondary biliary confluences and the intrapancreatic CBD were 90.7% and 87.0% for MRI with MRCP and 85.1% and 87.0% for MDCT with direct cholangiography. The differences were not statistically significant for either image set for either reviewer (p > 0.05). In the assessment of vascular involvement, lymph node metastasis, and tumor resectability, the readers diagnostic performance using MRI with MRCP was similar to that with MDCT with direct cholangiography (p > 0.05).nnnCONCLUSIONnIn the diagnosis of bile duct cancer with a noninvasive procedure, the information regarding tumor extent and resectability obtained with contrast-enhanced MRI combined with MRCP is comparable with that obtained with MDCT with direct cholangiography.

Diagnosis of Acute Appendicitis With Sliding Slab Ray-Sum Interpretation of Low-Dose Unenhanced CT and Standard-Dose IV Contrast-Enhanced CT Scans

OBJECTIVEnThe purpose of this study was to compare low-dose unenhanced CT with standard-dose i.v. contrast-enhanced CT in the diagnosis of appendicitis.nnnMATERIALS AND METHODSnTwo hundred seven adults with suspected appendicitis underwent CT with mean effective doses of both 4.2 and 8.0 mSv. Two radiologists retrospectively reviewed thin-section images by sliding a 5-mm-thick ray-sum slab. They rated the likelihood of appendicitis and appendiceal visualization on 5- and 3-point scales, respectively, and proposed alternative diagnoses. Likelihood > or = 3 was considered a positive diagnosis. Receiver operating characteristics analysis, the McNemar test, and the Wilcoxons signed-rank test were used.nnnRESULTSnSeventy-eight patients had appendicitis. The values of the area under the receiver operating characteristics curve were 0.98 for the low-dose unenhanced acquisition and 0.97 for the standard-dose contrast-enhanced acquisition for reader 1 (95% CI for the difference, -0.02 to 0.03) and 0.99 and 0.98 (-0.02 to 0.02) for reader 2. Sensitivity was 98.7% for low-dose unenhanced CT and 100% for standard-dose contrast-enhanced CT for reader 1 (p = 1.00) and 100% for both techniques for reader 2. Specificity was 95.3% and 93.0% (p = 0.25) and 96.9% and 96.9%. The interpretation was indeterminate (score 3) in 0.5% and 1.4% of cases for reader 1 (p = 0.63) and 0.5% and 0% for reader 2 (p = 1.00). A normal appendix was not visualized in 5.4% and 3.9% of cases by reader 1 (p = 0.63) and 3.9% and 2.3% of cases by reader 2 (p = 0.50). None of the patients whose appendix was not visualized had appendicitis. Diagnostic confidence, visualization score for a normal appendix, and correct alternative diagnosis tended to be compromised with use of low-dose unenhanced CT, showing a significant difference for a readers confidence in the diagnosis of appendicitis (p = 0.004). The two techniques were comparable in the diagnosis of appendiceal perforation.nnnCONCLUSIONnLow-dose unenhanced CT is potentially useful in the diagnosis of appendicitis.

Irreversible JPEG 2000 compression of abdominal CT for primary interpretation: assessment of visually lossless threshold

To estimate the visually lossless threshold for Joint Photographic Experts Group (JPEG) 2000 compression of contrast-enhanced abdominal computed tomography (CT) images, 100 images were compressed to four different levels: a reversible (as negative control) and irreversible 5:1, 10:1, and 15:1. By alternately displaying the original and the compressed image on the same monitor, six radiologists independently determined if the compressed image was distinguishable from the original image. For each reader, we compared the proportion of the compressed images being rated distinguishable from the original images between the reversible compression and each of the three irreversible compressions using the exact test for paired proportions. For each reader, the proportion was not significantly different between the reversible (0–1%, 0/100 to 1/100) and irreversible 5:1 compression (0–3%). However, the proportion significantly increased with the irreversible 10:1 (95–99%) and 15:1 compressions (100%) versus reversible compression in all readers (Pu2009<u20090.001); 100 and 95% of the 5:1 compressed images were rated indistinguishable from the original images by at least five of the six readers and all readers, respectively. Irreversibly 5:1 compressed abdominal CT images are visually lossless and, therefore, potentially acceptable for primary interpretation.

Added value of ultrasound re-evaluation for patients with equivocal CT findings of acute appendicitis: a preliminary study

PurposeTo prospectively estimate the additional diagnostic value of ultrasound (US) re-evaluation for patients with equivocal computed tomography (CT) findings of acute appendicitis.MethodsBetween April 2011 and October 2011, 869 consecutive patients with suspected appendicitis who were referred for CT were included. The likelihood of appendicitis was prospectively categorized into five categories. US re-evaluation was recommended for patients in the ‘equivocal appendix’ and ‘probably not appendicitis’ groups. The overall negative appendectomy rate during the study period was compared with the rate of the previous year, and negative appendectomy rates of the US and non-US evaluation groups were also compared.ResultsAmong 869 patients, 71 (8.2xa0%) had equivocal appendicitis findings and 63 (7.2xa0%) were diagnosed as probably not appendicitis. The sensitivity and specificity of CT combined with US re-evaluation group (100xa0% and 98.1xa0%, respectively) exceeded those of the CT alone group (93xa0% and 99xa0%; equivocal group considered as negative appendicitis, 100xa0% and 89.9xa0%; as positive, respectively, Pu2009<u20090.0001). After adding US re-evaluation, the overall negative appendectomy rate in our institution decreased from 3.4 to 2.3xa0%.ConclusionFor patients with equivocal CT findings of acute appendicitis, US re-evaluation can improve diagnostic accuracy and decrease the rate of negative appendectomies.Key Points• Misdiagnosis of appendicitis still occurs, especially in patients with equivocal radiological findings.• The sensitivity and specificity of CT followed by US exceeded those of CT alone.• After US re-evaluation, the negative appendectomy rate decreased from 3.4to 2.3u2009%.• US re-evaluation in equivocal cases helps diagnostic confidence and further management.

Evaluation of the longitudinal tumor extent of bile duct cancer: value of adding gadolinium-enhanced dynamic imaging to unenhanced images and magnetic resonance cholangiography.

Objective: To determine the added value of gadolinium-enhanced dynamic magnetic resonance (MR) images compared with unenhanced and MR cholangiography (MRC) images, to evaluate the longitudinal extension of bile duct cancer. Materials and Method: Thirty-three patients with hilar cholangiocarcinoma or common duct cancer who had undergone MRC, unenhanced, and gadolinium-enhanced dynamic MR images and surgery were included in this study. Two experienced radiologists independently reviewed 2 image sets in 2 steps, that is, the MRC set (unenhanced and MRC) and the combined image set (MRC set with dynamic images). At each step, the readers determined the tumor status according to the Bismuth-Corlette classification. The readers assigned their confidence levels on a 5-point scale regarding whether the tumor involved the secondary confluence of the bile duct and the intrapancreatic common bile duct. The radiologists diagnostic confidence of the 2 image sets was analyzed using receiver operating characteristic analysis. Results: Receiver operating characteristic analysis showed higher areas under the curve values when the combined image set was interpreted (0.990 ± 0.017 for reader 1 and 0.951 ± 0.027 for reader 2) than when the MRC set was interpreted (0.982 ± 0.017 for reader 1 and 0.902 ± 0.038 for reader 2); however, the difference was not statistically significant for either reader (P > 0.05). In addition, regarding evaluation of the tumor status according to the Bismuth-Corlette classification, the overall accuracy was higher for the combined image set than for the MRC set alone, but the difference was not significant (P > 0.05). When dynamic images were added to the MRC images, interobserver agreement improved from 0.72 to 0.84. Conclusions: The addition of contrast-enhanced dynamic images to unenhanced and MRC images did not significantly improve the diagnostic accuracy for assessment of the longitudinal extent of bile duct cancer.

Off-Site Smartphone Reading of CT Images for Patients With Inconclusive Diagnoses of Appendicitis From On-Call Radiologists

OBJECTIVEnThe purpose of this study was to simulate a mobile consultation in patients with inconclusive diagnosis of appendicitis made by on-call radiologists, as well as to measure the diagnostic confidence and performance of the mobile consultation.nnnMATERIALS AND METHODSnTwo off-site abdominal radiologists interpreted the CT images from 68 patients (including 29 patients with confirmed appendicitis) on a smart-phone for whom the preliminary CT reports by 25 in-house on-call radiologists were inconclusive. The smartphone readings were compared with the preliminary reports by on-call radiologists and with the original final reports by in-house abdominal radiologists. Heat maps, kappa statistics, Wilcoxon signed-rank tests, and ROC curves were used for data analysis.nnnRESULTSnThe heat maps and kappa statistics showed that the smartphone readings were more similar to the final reports than to the preliminary reports. In diagnosing or ruling out appendicitis, the smartphone readings were more confident than the preliminary reports (p ≤ 0.01) and did not significantly differ in diagnostic confidence from the final reports (p ≥ 0.19). The AUCs of the smartphone readings (0.91 and 0.92) did not differ significantly from those of the preliminary (0.85) or final (0.97) reports (p ≥ 0.09).nnnCONCLUSIONnWith the given study sample, the diagnostic performance of the off-site smartphone readings did not differ significantly from that of the in-house preliminary reports. However, the smartphone readings provided higher diagnostic confidence than the preliminary reports.

Color Doppler Twinkling Artifacts from Gallstones: In Vitro Analysis Regarding their Compositions and Architectures

The purpose of our study was to investigate the relationship between a twinkling artifact and the biochemical compositions of gallstones in phantom experiments. Fifty-two gallstones surgically extracted from 26 patients (26 cholesterol, 12 brown pigment and 14 black pigment stones) were included in the phantom study. Color Doppler sonography was performed to evaluate the occurrence of a twinkling artifact behind the stones. The artifacts were graded from grade 0 (no artifact) to grade 3 (very strong artifact). Micro computed tomography (CT) images were obtained to analyze the internal architecture and external surface of the stones. A total of 20 of 26 cholesterol stones (77%) produced grade 2 or 3 artifacts, whereas almost all the black pigment stones and more than half of the brown pigment stones produced no artifacts or grade 1 artifacts (p = 0.0010). The sensitivity and specificity of grade 2 or greater artifacts for cholesterol stones were 76.9% and 76.9%, respectively. The composition of the stones was strongly correlated with the internal shape on the micro CT image. Cholesterol stones with rough surfaces did not show stronger intensities of the artifacts than those with smooth surfaces (p > 0.05). In conclusion, most of the prominent artifacts arose from cholesterol stones having radial or radial-concentric internal architectures, whereas the black pigment stones mostly produced little artifact.

Ultrasound assessment of gastric volume in children after drinking carbohydrate-containing fluids

BACKGROUNDnGastric ultrasound is a valid tool for non-invasive assessment of the nature and volume of gastric contents in adults and children. Perioperative fasting guidelines recommend oral carbohydrates up to 2 h before elective surgery. We evaluated gastric volume in children using ultrasound before and after drinking carbohydrate fluids before surgery.nnnMETHODSnPaediatric patients younger than 18 yr old undergoing elective surgery were enrolled. Initial ultrasound assessment of gastric volume was performed after fasting for 8 h. Two hours before surgery, patients were given carbohydrate drinks: 15 ml kg(-1) for patients younger than 3 yr old and 10 ml kg(-1) for those more than 3 yr old. Before induction of general anaesthesia, the gastric volume was reassessed. Parental satisfaction scores (0=totally satisfied, 10=totally dissatisfied) and complications were recorded.nnnRESULTSnOf the 86 enrolled patients, 79 completed the study; three refused to ingest the requested volume, and surgery was delayed for more than 2 h in four patients. The mean (sd) of the initial and second ultrasound measurements were 2.09 (0.97) and 1.85 (0.94) cm(2), respectively (P=0.01; mean difference 0.24 cm(2), 95% confidence interval 0.06-0.43). The median (interquartile range) satisfaction score was 2.4 (0-6). Two instances of postoperative vomiting and one instance of postoperative nausea occurred.nnnCONCLUSIONSnCarbohydrate fluids ingested 2 h before surgery reduced the gastric volume and did not cause serious complications in paediatric patients. Parents were satisfied with the preoperative carbohydrate drink. Children may benefit from drinking carbohydrate fluids up to 2 h before elective surgery.nnnCLINICAL TRIAL REGISTRATIONncris.nih.go.kr (KCT0001546).

Gastric remnant infarction following laparoscopy-assisted distal gastrectomy: CT diagnosis in two cases

We report two cases of gastric remnant infarction following laparoscopy-assisted distal gastrectomy for the treatment of early gastric cancer. In both cases, the infarction was diagnosed with contrast-enhanced computer tomography.