Diagnosis of acute appendicitis with sliding slab ray-sum interpretation of low-dose unenhanced CT and standard-dose i.v. contrast-enhanced CT scans.

Seo, Hyobin,Lee, Kyoung Ho,Kim, Hyuk Jung,Kim, Kyuseok,Kang, Sung-Bum,Kim, So Yeon,Kim, Young Hoon American Roentgen Ray Society, etc.] 2009 AJR Vol.193 No.1

<P>OBJECTIVE: The purpose of this study was to compare low-dose unenhanced CT with standard-dose i.v. contrast-enhanced CT in the diagnosis of appendicitis. MATERIALS AND METHODS: Two 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 Wilcoxon's signed-rank test were used. RESULTS: Seventy-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 reader's confidence in the diagnosis of appendicitis (p = 0.004). The two techniques were comparable in the diagnosis of appendiceal perforation. CONCLUSION: Low-dose unenhanced CT is potentially useful in the diagnosis of appendicitis.</P>

The spectrum of vascularized superficial soft-tissue tumors on sonography with a histopathologic correlation: Part 1, benign tumors.

Jin, Wook,Kim, Gou Young,Park, So Young,Chun, Young Soo,Nam, Deok Ho,Park, Ji Seon,Ryu, Kyung Nam American Roentgen Ray Society, etc.] 2010 American Journal of Roentgenology Vol.195 No.2

<P>The objective of this article is to illustrate the sonographic findings of benign, vascularized superficial soft-tissue tumors.</P>

Perfusion CT of the brain using 40-mm-wide detector and toggling table technique for initial imaging of acute stroke.

Youn, Sung Won,Kim, Jae Hyoung,Weon, Young-Cheol,Kim, Sung Hyun,Han, Moon-Ku,Bae, Hee-Joon American Roentgen Ray Society, etc.] 2008 American Journal of Roentgenology Vol.191 No.3

<P>OBJECTIVE: Limited coverage of the brain in the z-axis has been a drawback of perfusion CT. The purpose of this study was to evaluate the usefulness of perfusion CT with extended coverage in the z-axis for the assessment of acute stroke in an emergent clinical setting. MATERIALS AND METHODS: Fifty-eight patients who underwent 80-mm-coverage perfusion CT within 24 hours after stroke onset were included. Perfusion CT was performed using a 64-MDCT unit equipped with 40-mm-wide detector and the toggling table technique. Lesion detection by perfusion CT was analyzed using follow-up diffusion-weighted imaging and MR angiography as the reference standards. More conventional 20-mm-coverage perfusion CT was simulated by extracting data obtained at the basal ganglia level for comparison with 80-mm-coverage perfusion CT. RESULTS: Fifty-one patients had acute infarctions and seven patients did not. For 80-mm-coverage perfusion CT, perfusion abnormality was detected in 42 of 51 patients (sensitivity, 82.4%; and specificity, 85.7%). When patients with small artery disease (small acute infarctions in the basal ganglia, thalamus, corona radiata, and pons) were excluded, sensitivity increased to 92.3%. As compared with 80-mm-coverage perfusion CT, 20-mm-coverage perfusion CT missed nine acute infarctions located above or below the level of the basal ganglia (p = 0.0039). CONCLUSION: Perfusion CT with 80-mm-coverage was found to be useful as an initial imaging method in acute ischemic stroke, although it had low sensitivity for detecting small acute infarctions. In particular, this technique provided higher lesion detection than 20-mm-coverage perfusion CT.</P>

3-T MRI: usefulness for evaluating primary lung cancer and small nodules in lobes not containing primary tumors.

Yi, Chin A,Jeon, Tae Yeon,Lee, Kyung Soo,Lee, Jung Hee,Seo, Joon Beom,Kim, Yoon Kyung,Chung, Myung Jin American Roentgen Ray Society 2007 American Journal of Roentgenology Vol.189 No.2

<P>OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of 3-T MRI in the detection and characterization of primary non-small cell lung cancer and of small nodules in lobes not containing primary tumors. MATERIALS AND METHODS: From July 2005 to May 2006, 127 patients (99 men, 28 women; mean age, 63 years) with histopathologically proven non-small cell lung cancer underwent both CT and MRI of the chest. Transverse MR images were obtained with T1-weighted 3D turbo field-echo and T2-weighted triple inversion black blood turbo spin-echo sequences on a 3-T MRI system. Two chest radiologists assessed CT images and then MR images. The morphologic features of lung cancer and the detectability of small nodules in lobes not containing primary tumors on MR images were compared with the findings on CT images, which were the reference standard. RESULTS: The morphologic characteristics of primary cancer found on both T1- and T2-weighted images corresponded to those on CT images. The overall rates of detection of nodules in lobes not containing primary tumors were 57% (184 of 323 nodules) and 56% (180 of 323 nodules) on T1- and T2-weighted images, respectively (p = 0.64). In terms of detection of non-calcified nodules 5-10 mm in diameter, both T1- and T2-weighted images had a detection rate of 92% (48 of 52 nodules) (p = 1.00). CONCLUSION: Both T1-weighted 3D turbo field-echo and T2-weighted triple inversion black blood turbo spin-echo 3-T MR images depict clinically significant small (5-10 mm in diameter) noncalcified pulmonary nodules nearly as well as do CT scans.</P>

Artifacts in slab average-intensity-projection images reformatted from JPEG 2000 compressed thin-section abdominal CT data sets.

Kim, Bohyoung,Lee, Kyoung Ho,Kim, Kil Joong,Mantiuk, Rafal,Kim, Hye-ri,Kim, Young Hoon American Roentgen Ray Society, etc.] 2008 American Journal of Roentgenology Vol.190 No.6

<P>OBJECTIVE: The objective of our study was to assess the effects of compressing source thin-section abdominal CT images on final transverse average-intensity-projection (AIP) images. MATERIALS AND METHODS: At reversible, 4:1, 6:1, 8:1, 10:1, and 15:1 Joint Photographic Experts Group (JPEG) 2000 compressions, we compared the artifacts in 20 matching compressed thin sections (0.67 mm), compressed thick sections (5 mm), and AIP images (5 mm) reformatted from the compressed thin sections. The artifacts were quantitatively measured with peak signal-to-noise ratio (PSNR) and a perceptual quality metric (High Dynamic Range Visual Difference Predictor [HDR-VDP]). By comparing the compressed and original images, three radiologists independently graded the artifacts as 0 (none, indistinguishable), 1 (barely perceptible), 2 (subtle), or 3 (significant). Friedman tests and exact tests for paired proportions were used. RESULTS: At irreversible compressions, the artifacts tended to increase in the order of AIP, thick-section, and thin-section images in terms of PSNR (p < 0.0001), HDR-VDP (p < 0.0001), and the readers' grading (p < 0.01 at 6:1 or higher compressions). At 6:1 and 8:1, distinguishable pairs (grades 1-3) tended to increase in the order of AIP, thick-section, and thin-section images. Visually lossless threshold for the compression varied between images but decreased in the order of AIP, thick-section, and thin-section images (p < 0.0001). CONCLUSION: Compression artifacts in thin sections are significantly attenuated in AIP images. On the premise that thin sections are typically reviewed using an AIP technique, it is justifiable to compress them to a compression level currently accepted for thick sections.</P>

Prediction of perceptible artifacts in JPEG 2000-compressed chest CT images using mathematical and perceptual quality metrics.

Kim, Bohyoung,Lee, Kyoung Ho,Kim, Kil Joong,Mantiuk, Rafal,Hahn, Seokyung,Kim, Tae Jung,Kim, Young Hoon American Roentgen Ray Society, etc.] 2008 American Journal of Roentgenology Vol.190 No.2

<P>OBJECTIVE: The objective of our study was to determine whether peak signal-to-noise ratio (PSNR) and a perceptual quality metric (High-Dynamic Range Visual Difference Predictor [HDR-VDP]) can predict the presence of perceptible artifacts in Joint Photographic Experts Group (JPEG) 2000-compressed chest CT images. MATERIALS AND METHODS: One hundred chest CT images were compressed to 5:1, 8:1, 10:1, and 15:1. Five radiologists determined if the original and compressed images were identical (negative response) or different (positive response). The correlation between the results for each metric and the number of readers with positive responses was evaluated using Spearman's rank correlation test. Using the pooled readers' responses as the reference standard, we performed receiver operating characteristic (ROC) analysis to determine the cutoff values balancing sensitivity and specificity and yielding 100% sensitivity in each metric. These cutoff values were then used to estimate the visually lossless thresholds for the compressions for the 100 original images, and the accuracy of the estimates of two metrics was compared (McNemar test). RESULTS: The correlation coefficients were -0.918 and 0.925 for PSNR and the HDR-VDP, respectively. The areas under the ROC curves for the two metrics were 0.983 and 0.984, respectively (p = 0.11). The PSNR and HDR-VDP accurately predicted the visually lossless threshold for 69% and 72% of the 100 images (p = 0.68), respectively, at the cutoff values balancing sensitivity and specificity and for 43% and 47% (p = 0.22), respectively, at the cutoff values reaching 100% sensitivity. CONCLUSION: Both metrics are promising in predicting the perceptible compression artifacts and therefore can potentially be used to estimate the visually lossless threshold.</P>

CT findings in hydrocarbon pneumonitis after diesel fuel siphonage.

Yi, Mi Seon,Kim, Kun-Il,Jeong, Yeon Joo,Park, Hye Kyung,Lee, Min Ki American Roentgen Ray Society, etc.] 2009 American Journal of Roentgenology Vol.193 No.4

<P>The purpose of this study was to assess CT findings in a series of patients with hydrocarbon pneumonitis after diesel fuel siphonage.</P>

Typical and atypical manifestations of serous cystadenoma of the pancreas: imaging findings with pathologic correlation.

Choi, Jin-Young,Kim, Myeong-Jin,Lee, Jae Young,Lim, Joon Seok,Chung, Jae Joon,Kim, Ki Whang,Yoo, Hyung Sik American Roentgen Ray Society, etc.] 2009 American Journal of Roentgenology Vol.193 No.1

<P>The purpose of this article is to present the typical and atypical manifestations of serous cystadenoma, which can be visualized with cross-sectional imaging.</P>

The usefulness of virtual MR arthroscopy as an adjunct to conventional MR arthrography in detecting anterior labral lesions of the shoulder.

Song, Ho-Taek,Huh, Yong-Min,Kim, Sungjun,Kim, Sung-Jae,Suh, Jin-Suck American Roentgen Ray Society, etc.] 2009 American Journal of Roentgenology Vol.192 No.4

<P>OBJECTIVE: The objective of this study was to investigate the usefulness of virtual MR arthroscopy as an adjunct to conventional MR arthrography in detecting various anteroinferior glenoid labral lesions. MATERIALS AND METHODS: The study group was composed of 28 patients (22 men and six women; mean age, 25 years) who underwent direct MR arthrography of the shoulder as well as arthroscopy due to recurrent shoulder dislocations. MR arthrography examinations were reviewed retrospectively with radiologists blinded to the arthroscopic diagnoses. Virtual MR arthroscopy was produced from fat-suppressed 3D gradient-recalled echo MR arthrography using volume-rendering software. The sensitivity, specificity, and accuracy for diagnosis were calculated. The diagnostic performances were validated by receiver operating characteristic curve analysis. RESULTS: The structure of the glenoid labrum was well visualized in a 3D perspective, and characterization of the injured anterior glenoid labrum was aided by adjunct use of virtual MR arthroscopy. The accuracy for detecting classic Bankart, anterior labroligamentous periosteal sleeve avulsion, and Perthes lesions improved to 85.7%, 85.7%, and 92.9%, respectively, with adjunct virtual MR arthroscopy with MR arthrography versus 78.6%, 82.1%, and 89.3%, respectively, with MR arthrography alone. A statistically significant improvement of the diagnostic capability of MR arthrography with adjunct virtual MR arthroscopy was proven for the detection of a classic Bankart lesion (p < 0.05). CONCLUSION: Having a 3D perspective to validate chronic recurrent glenoid labral injuries of the shoulder facilitated understanding of the anatomic relationships and helped diagnosis. Adjunct virtual MR arthroscopy is potentially useful for detecting and characterizing chronic recurrent glenoid labral lesions to improve diagnosis.</P>

Sonographic surveillance for the detection of contralateral metachronous breast cancer in an Asian population.

Kim, Min Jung,Kim, Eun-Kyung,Kwak, Jin Young,Park, Byeong-Woo,Kim, Seung-Il,Sohn, Joohyuk,Oh, Ki Keun American Roentgen Ray Society, etc.] 2009 American Journal of Roentgenology Vol.192 No.1

<P>OBJECTIVE: This study was designed to assess the diagnostic indexes of sonographic surveillance with mammography for the detection of metachronous contralateral breast cancer. MATERIALS AND METHODS: Between January 2003 and December 2003, 1,706 breast sonographic examinations were performed by three radiologists in 1,256 Asian women with a history of surgery for breast cancer in one breast as an adjunct screening test to mammography in an academic medical center. We evaluated the biopsy recommendation rate, a diagnostic index, of the combination of whole-breast sonography and mammography for the detection of contralateral metachronous breast cancers and the positive predictive value (PPV) of this biopsy recommendation rate. RESULTS: Based on 1,706 examinations in 1,256 women, the biopsy recommendation rate was 3.5% per patient and 2.6% per examination. The PPV of the biopsy recommendation rate was 41.0% with 18 breast cancers diagnosed (cancer detection rate, 1.4% per patient and 1.1% per examination). Among these cancers, two were detected on sonography alone. One false-negative cancer was found on the next sonographic examination but could not be seen on the next mammographic examination. CONCLUSION: With a false-negative rate of only 0.06% and a PPV of 41.0% for the biopsy recommendation rate, our results suggest that annual sonography could be a useful adjunctive tool to mammography for the detection of metachronous contralateral cancers.</P>