Jui-Sheng Hsu

Effect of intravenous gadolinium-DTPA on diffusion-weighted magnetic resonance images for evaluation of focal hepatic lesions.

Objective: Diffusion-weighted imaging (DWI) is usually performed before administration of intravenous contrast agents. Repetition of DWI is occasionally necessary after contrast administration, but the effects of contrast material on DWI and apparent diffusion coefficient (ADC) values in the abdomen have not yet been fully examined. The purpose of this work is to assess whether administration of gadolinium-based contrast material significantly affects DWI and ADC values at the focal hepatic lesions. Methods: The results of DWI at 3.0 T (Signa VH3; GE Medical Systems, Milwaukee, WI) were examined in 20 patients (age range: 33-86 years, mean age = 68 years) who were evaluated by means of a hepatic protocol at our hospital. Among the 20 patients studied, a total of 57 lesions were detected. Diffusion-weighted imaging was obtained using single-shot echo planar imaging with a b value of 500 s/mm2. Patients were injected with 0.1 mmol/kg gadopentetate dimeglumine. The signal-to-noise ratio (SNR) of the liver and the hepatic lesions was examined, and the contrast-to-noise ratio (CNR) of each lesion was evaluated. In addition, the ADC values calculated from the DWI were compared before and after administration of contrast agent. The statistical significance of differences between precontrast and postcontrast administration was determined by use of a paired t test. Results: The SNR and CNR of the DWI were not significantly different before and after administration of contrast agent. The ADC values tended to decrease after administration of contrast agent for each focal hepatic lesion and the liver, although they did not reach statistical significance. Conclusion: There was no significant difference before and after administration of contrast agent in the SNR or CNR of DWI. This indicates the feasibility of postcontrast DWI as a substitute for an unsuccessful precontrast-enhanced study in clinical practice.

End-Stage Renal Disease: In Vivo Diffusion-Tensor Imaging of Silent White Matter Damage

PURPOSE To characterize and compare regional differences in anisotropy in patients with end-stage renal disease (ESRD) and in control subjects to understand the effect of ESRD and hemodialysis on the microstructures of white matter. MATERIALS AND METHODS This study was approved by an institutional review board; written informed consent was obtained. From March 2007 to December 2007, 34 patients (16 men, 18 women; mean age, 40.0 years; range, 26-50 years) with ESRD who were undergoing dialysis and 35 control subjects (16 men, 19 women; mean age, 38.3 years; range, 25-49 years) were enrolled. There was no significant sex or age difference between the ESRD and control groups. By using a 1.5-T imager, fractional anisotropy (FA) data obtained at diffusion-tensor magnetic resonance (MR) imaging (echo-planar imaging, 33 directions; b value, 1000 sec/mm(2)) and at T2-weighted fluid-attenuated inversion recovery (FLAIR) MR imaging of the bilateral parietal, frontal, occipital, and temporal lobe white matter, as well as the genu and splenium of the corpus callosum, were compared. The Cognitive Abilities Screening Instrument (CASI) was administered to all participants at imaging. RESULTS The ESRD group had significantly lower FA values in all regions than the control group. FA values were generally lower in older patients and in those who had been undergoing dialysis for a longer duration. Duration of dialysis was more often than age found to be correlated with differences in FA values. In areas in which there was a significant correlation between age, duration, and FA values, the regression coefficients were greater for those who had been undergoing dialysis longer than for those who were older. Patients with ESRD had significantly lower CASI scores than control subjects (P = .03). There were no significant group differences in FLAIR values (P = .25-.89). CONCLUSION Changes in FA values may be used to follow-up white matter changes in patients with ESRD who are undergoing maintenance dialysis. SUPPLEMENTAL MATERIAL http://radiology.rsnajnls.org/cgi/content/full/2523080484/DC1.

Comparison of radiographic landmarks and the echocardiographic SVC/RA junction in the positioning of long-term central venous catheters

Background:  When implanting a permanent central venous catheter, the usual aim is to place the tip at the superior vena cava/right atrial (SVC/RA) junction. However, data validating radiographic landmarks of the SVC/RA junction are limited. This investigation was undertaken to compare the radiographic landmarks with the SVC/RA junction as determined by transesophageal echocardiography (TEE).

Correlation between EGFR mutation status and computed tomography features in patients with advanced pulmonary adenocarcinoma.

Purpose: To correlate computed tomography (CT) imaging features and epidermal growth factor receptor (EGFR) mutation status in patients with advanced lung adenocarcinoma. Materials and Methods: Patients with advanced pulmonary adenocarcinoma who were diagnosed between January 1, 2009 and December 31, 2011 and who had available chest CT and their tumors analyzed for EGFR mutations at a university hospital were enrolled in this retrospective study. Two radiologists independently evaluated the CT images and recorded the target lesions size, shape, margin, density, and the presence or absence of an air bronchogram and calcification. Results: One hundred and forty-nine patients were enrolled into this study (66 men, 83 women), with a mean age of 63±11 years (range 32 to 89 y). Seventy-eight (52.3%) patients had EGFR mutations. The tumors in the patients harboring no EGFR mutations (EGFR wild type) were larger than in those whose tumors harbored EGFR mutations (P=0.01). An irregular shape was more common in the tumors with wild-type EGFR (P=0.01), and an oval shape was more common in tumors with EGFR mutations. Tumors with exon 21 mutations were larger than those with exon 19 deletions (P=0.02). Air bronchograms were more common in tumors with exon 19 deletions than in those with wild-type EGFR or exon 21 mutations (P=0.004 and 0.01, respectively). Calcification was more common in the tumors with wild-type EGFR than in those with EGFR mutations (P=0.03). Conclusions: Adenocarcinomas with wild-type EGFR were significantly associated with larger tumors and an irregular shape. In particular, calcification was more common in the tumors with wild-type EGFR than in those with EGFR mutations. In addition, air bronchograms were more common in the tumors with exon 19 deletions.

Split-Bolus Portal Venous Phase Dual-Energy CT Urography: Protocol Design, Image Quality, and Dose Reduction

OBJECTIVE The purpose of this study is to evaluate the image quality of split-bolus portal venous phase urography and the potential reduction of radiation dose by using a second-generation dual-source dual-energy CT (DECT) scanner. MATERIALS AND METHODS DECT urography was performed in 84 patients. Unenhanced CT was performed 20 minutes after drinking 800 mL of water. The split-bolus protocol consisted of a sequence of injections, as follows: 200 mL of normal saline (2.0 mL/s), 50 mL of contrast medium (2.5 mL/s) at 0 second, 70 mL of contrast medium (2.5 mL/s) at 360 seconds, and a saline flush of 25 mL. The scan was started at 420 seconds. Virtual unenhanced images were reconstructed from contrast-enhanced images. The mean CT density and signal-to-noise ratio (SNR) of the renal parenchyma, vessels, upper urinary tract, normal reference tissues, and tumors were measured for image quantitative analysis. Image quality and opacification of the collecting systems were rated by two radiologists using 3- or 4-point scales. RESULTS The SNR of all measured sites, except the renal pelvis, showed a statistically significant correlation (p < 0.001) between the true unenhanced and virtual unenhanced images. The overall sensitivity of stone detection was 87.5% (28/32) in virtual unenhanced images. Image quality of the renal parenchyma, arteries, and veins was excellent in 59.5%, 75.0%, and 97.6% of cases, respectively. Opacification of the intrarenal collecting systems, proximal, middle, and distal ureters, and bladder was complete in 92.9%, 83.9%, 78.6%, 77.4%, and 26.2% of patients, respectively. Omitting the unenhanced scan can reduce the mean radiation dose from 15.6 to 6.7 mSv. CONCLUSION Portal venous phase split-bolus DECT urography provides sufficient image quality with potential to reduce radiation exposure.

MDCT for Differentiation of Category T1 and T2 Malignant Lesions from Benign Gastric Ulcers

OBJECTIVE The purpose of this study was to evaluate MDCT parameters for differentiating malignant (category T1 and T2) from benign gastric ulcers and to evaluate the performance characteristics of these predictors with optimal cutoff points determined in receiver operator characteristic analysis. SUBJECTS AND METHODS The subjects were 26 patients with gastric cancer (11 with T1 lesions, 15 with T2 lesions) and 26 patients with benign gastric ulcer. MDCT and virtual gastroscopic findings were analyzed according to four qualitative criteria: ulcer shape, base, and margin and changes in adjacent folds. The quantitative criteria ulcer size, thickness of the gastric wall around an ulcer, thickness of the enhanced ulcer base, and enhancement around an ulcer were measured on multiplanar reconstruction images. We calculated the sensitivity and specificity of each quantitative criterion. Receiver operator characteristic analysis was used to identify cutoff points yielding optimal sensitivity and specificity for the diagnosis of gastric cancer. RESULTS On virtual gastroscopy, ulcer shape and margin and gastric fold changes had sensitivities of 80.8%, 84.6%, and 90.9% and specificities of 76.9%, 73.1%, and 77.8%, respectively, in the diagnosis of gastric cancer. On multiplanar reconstruction images, thickness of the enhanced ulcer base and enhancement around the ulcer had sensitivities of 80.8% and 73.1% and specificities of 100% and 100%. CONCLUSION MDCT combined with virtual gastroscopy and multiplanar reconstruction enhances the morphologic details of gastric ulcers and is a useful way to differentiate malignant (T1 and T2) and benign gastric ulcers.

Duodenal Metastasis of Malignant Pleural Mesothelioma

Metastatic malignant mesothelioma of the pleura is uncommon at the time of initial diagnosis. The gastrointestinal lumen is rarely found at autopsy in patients with widespread disease. Here, we describe an extremely rare case of isolated duodenal metastasis of sarcomatoid mesothelioma of the pleura in a 73-year-old man, without memory of any direct exposure to asbestos. The possibility of gastrointestinal tract metastasis should be considered in the presence of anemia or positive occult blood test in patients with malignant pleural mesothelioma.

Pleural Tags on CT Scans to Predict Visceral Pleural Invasion of Non-Small Cell Lung Cancer That Does Not Abut the Pleura.

PURPOSE To evaluate the association of pleural tags with visceral pleural invasion of non-small cell lung cancer (NSCLC) that does not abut the pleural surface. MATERIALS AND METHODS This retrospective study was approved by the institutional review board. Informed consent was waived. The study of NSCLC that does not abut the pleura in 141 patients (44 patients [31.2%] with visceral pleural invasion proved by pathologic analysis and 97 patients [68.8%] without pleural invasion) was conducted at a single tertiary center. The pleural tags were classified into three types (type 1, one or more linear pleural tag; type 2, one or more linear pleural tag with soft tissue component at the pleural end; and type 3, one or more soft tissue cord-like pleural tag) and prioritized into types 3, 2, and 1 when more than one type was present. Diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive likelihood ratio (LR) were calculated. RESULTS In the absence of pleural tags, no pleural invasion was found. The presence of type 2 pleural tags was moderately associated with visceral pleural invasion with the following results: positive LR, 5.06; accuracy, 71%; sensitivity, 36.4%; specificity, 92.8%; PPV, 76.2%; and NPV, 69.6%. Type 1 pleural tags provided weak evidence to rule out visceral pleural invasion (positive LR, 0.38). Type 3 pleural tags indicated minimal increase in the likelihood of visceral pleural invasion (positive LR, 1.68). CONCLUSION Type 2 pleural tags on conventional CT images can increase the accuracy of early diagnosis of visceral pleural invasion by NSCLC that does not abut the pleura.

Diagnostic Performance of Split-Bolus Portal Venous Phase Dual-Energy CT Urography in Patients With Hematuria

OBJECTIVE The purpose of this study is to evaluate the diagnostic performance of split-bolus portal venous phase dual-energy CT (DECT) urography in patients with hematuria. MATERIALS AND METHODS True unenhanced and split-bolus portal venous phase contrast-enhanced weighted-average images were obtained in 171 patients with hematuria. Virtual unenhanced and iodine-overlay images were reconstructed from contrast-enhanced 80-kVp and tin-filtered 140-kVp scans. Images were independently reviewed by two radiologists who were blinded to the final diagnoses in two separate reading sessions: virtual unenhanced and iodine-overlay images (single phase) in the first session and true unenhanced and contrast-enhanced weighted-average images (dual phase) in the second session (mean ± SD, 52 ± 8 days later). Sensitivity, specificity, and accuracy of mass detection were calculated from the data of both reading sessions. The number of calculi detected on virtual unenhanced images was compared with the number detected on true unenhanced images. The difference in radiation dose between the single- and dual-phase protocols was calculated. The statistical significance was determined by ANOVA. RESULTS The sensitivity, specificity, and accuracy were 98.7%, 98.9%, and 98.8%, respectively, for the single-phase approach to malignant mass detection and 98.7%, 97.9%, and 98.3%, respectively, for the dual-phase approach (p > 0.05 for all comparisons). The overall sensitivity of stone detection was 86.7% (39/45) for virtual unenhanced images. Omitting the unenhanced scan reduced the mean radiation dose from 15.4 to 6.7 mSv. CONCLUSION The diagnostic performance of both the single- and dual-phase approaches of portal venous phase split-bolus DECT urography is equally good in patients with hematuria, and single-phase acquisition has the added benefit of radiation reduction.

Utility of the Iodine Overlay Technique and Virtual Nonenhanced Images for the Preoperative T Staging of Colorectal Cancer by Dual-Energy CT with Tin Filter Technology

Objectives To evaluate the diagnostic accuracy and the potential radiation dose reduction of dual-energy CT (DECT) for tumor (T) staging of colorectal cancer (CRC) using iodine overlay (IO) and virtual nonenhanced (VNE) images. Materials and Methods This retrospective study included 103 consecutive patients who underwent nonenhanced CT and enhanced DECT for preoperative CRC staging. Enhanced weighted-average (WA), IO and VNE images were reconstructed from enhanced 80 kVp and Sn140 kVp scans. Two radiologists assessed image qualities of the true nonenhanced (TNE) and VNE images. For T-staging, another two radiologists independently interpreted all scans in two separate reading sessions: in the first session, only images derived from the single phase DECT acquisition (IO and VNE images) were read. In the second reading session after 30 to 50 (average:42) days, the same assessment was again performed with the TNE and enhanced WA images thereby simulating conventional dual-phase single-energy CT. The tumor node metastasis (TNM) system was used for staging with histopathologic reports as gold standard. Analysis of variance was used for statistical analysis. Results The signal-to-noise ratios (SNRs) of the tumors and normal reference tissues showed significant correlation between the TNE and VNE images (P<0.01). The mean iodine overlay value (48.4 HU±12.2) and enhancement (49.4 HU±11.8) value of CRCs had no significant difference (P = 0.52).The mean image noise on TNE (5.0±1.1) and VNE (5.3±1.1) images were similar (P = 0.07). The quantitative qualities of the VNE images were mildly inferior to the TNE images. Overall accuracy of T-stage CRC when using single-phase acquisition was slightly better than the dual-phase acquisition (90.3% vs 87.4%) (P = 0.51). The mean dose of the single-phase DECT acquisition was 6.2mSv comparing with 14.3mSv of dual-phase. Conclusion Single-phase DECT using IO and VNE images yields a high accuracy in T-staging of CRCs. Thereby, the radiation exposure of the patients can be reduced.