Hyo Sung Kwak

Detection of hepatocellular carcinoma: gadoxetic acid-enhanced 3-dimensional magnetic resonance imaging versus multi-detector row computed tomography.

Purpose: The aim of this study was to compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced magnetic resonance imaging (MRI) with multi-detector row computed tomography (MDCT) for the detection of hepatocellular carcinomas (HCCs). Materials: Sixty-two patients (81 HCCs) who underwent MDCT and gadoxetic acid-enhanced MRI using a 3-dimensional volumetric interpolated technique with a mean interval of 7 days (range, 3-11 days) were included in this study. Two observers reached a consensus on 2 sets of images: the gadoxetic acid set (unenhanced, early dynamic, 10-minute, and 20-minute hepatocyte phase images) and the 3-phase MDCT. Diagnostic accuracy and sensitivity were evaluated using the alternative-free response receiver operating characteristic method. Results: There was a trend toward increased area under the receiver operating characteristic curve (Az value) for the gadoxetic acid set (0.963) as compared with the MDCT (0.930), but no significant difference was found (P = 0.41). Sensitivity of the gadoxetic acid set (91.4%) was better than that of the MDCT (71.6%; P = 0.0001). There were 12 lesions that showed only arterial hypervascularization on MDCT but showed arterial hypervascularization and delayed hypointensity on the gadoxetic acid set. Conclusions: Gadoxetic acid-enhanced MRI, including hepatocyte phase imaging, is more sensitive than MDCT for the detection of HCCs.

Three-dimensional dynamic liver MR imaging using sensitivity encoding for detection of hepatocellular carcinomas: comparison with superparamagnetic iron oxide-enhanced mr imaging.

To assess the diagnostic performance of three‐dimensional dynamic liver imaging with sensitivity encoding (SENSE), including double arterial phase images and increased resolution, by comparing it to superparamagnetic iron oxide (SPIO)‐enhanced magnetic resonance (MR) imaging for the detection of hypervascular hepatocellular carcinoma (HCC).

High resolution MR imaging in patients with symptomatic middle cerebral artery stenosis

PURPOSE High resolution magnetic resonance imaging (HRMRI) has been used as an imaging modality to depict the intracranial artery wall. The aim of this study was to compare images of the vessel wall between symptomatic and asymptomatic atherosclerotic plaques of the middle cerebral artery (MCA) using HRMRI. MATERIALS AND METHODS From September 2009 to August 2010 we prospectively screened consecutive patients for MCA stenosis using time-of-flight (TOF) MR angiography. We studied 14 patients with symptomatic MCA stenosis and 16 patients with asymptomatic MCA stenosis. The HRMRI protocol included three different scans: T1-, T2-, and proton density (PD)-weighted black blood MRI. The cross-sectional images of the MCA wall on HRMRI were compared between the two groups based on the degree of stenosis, remodeling ratio, outward or inward remodeling, plaque signal intensity, plaque surface irregularity, and presence of an intact inner wall. RESULTS The degree of MCA stenosis and the ratio of plaque thickening to patent lumen in the symptomatic group were significantly higher than in the asymptomatic group. Outward remodeling of the stenotic area in symptomatic group was significantly higher than that seen in the asymptomatic group, and the reverse was true for inward remodeling of the stenotic area (it was significantly higher in the asymptomatic group compared to the symptomatic group). T2- and PD-weighted high signal foci, eccentric wall thickening, and plaque volume in the stenotic area were all similar between the two groups. CONCLUSIONS HRMRI has the potential to distinguish between atherosclerotic plaques in symptomatic and asymptomatic MCA stenoses.

Detection and characterization of focal hepatic tumors: A comparison of T2-weighted MR images before and after the administration of gadoxectic acid

To evaluate if T2‐weighted images (T2WI) after administration of gadoxetic acid have diagnostic capability comparable to precontrast T2WI in the detection and characterization of focal liver lesions.

Detection of liver metastases: Gadoxetic acid-enhanced three-dimensional MR imaging versus ferucarbotran-enhanced MR imaging

PURPOSE To compare the diagnostic performance of gadoxetic acid-enhanced MRI with ferucarbotran-enhanced MRI for the detection of liver metastases. MATERIALS AND METHODS Thirty-six patients with 80 liver metastases who underwent gadoxetic acid-enhanced MRI using a three-dimensional volumetric interpolated technique and ferucarbotran-enhanced MRI with a mean interval of 7 days (range, 5-10 days) were included in this study. Two observers independently interpreted the two sets of images - the gadoxetic acid set (unenhanced, early dynamic and 20min delayed phase images) and the ferucarbotran set (unenhanced and ferucarbotran-enhanced T2*-weighted-gradient echo and T2-weighted turbo spin echo images). Diagnostic accuracy was evaluated using the alternative-free response receiver operator characteristic (ROC) method. Sensitivity and positive predictive value were also evaluated. RESULTS There was a trend toward increased areas under the ROC curve (Az values) for the gadoxetic acid set (0.950, 0.948) as compared with the ferucarbotran set (0.941 and 0.939) of images, but no significant difference was found for both observers (p<0.05). Sensitivities of the gadoxetic acid set (93.8% and 92.5%) were also slightly better than those of the ferucarbotran set (88.8% and 87.5%) with no significant difference (p=0.13). The two image sets showed similar positive predictive values (98.7% and 98.6%, respectively). CONCLUSIONS Gadoxetic acid-enhanced MRI showed comparable diagnostic performance to ferucarbotran-enhanced MRI for the detection of liver metastases.

Usefulness of combining sequentially acquired gadobenate dimeglumine-enhanced magnetic resonance imaging and resovist-enhanced magnetic resonance imaging for the detection of hepatocellular carcinoma: comparison with computed tomography hepatic arteriography and computed tomography arterioportography using 16-slice multidetector computed tomography.

Objective: To investigate the diagnostic efficacy of sequentially acquired gadobenete dimeglumine-enhanced 3-dimensional dynamic magnetic resonance imaging (MRI) and Resovist-enhanced MRI for detecting hepatocellular carcinoma (HCC) by comparing with combined computed tomography (CT) hepatic arteriography (CTHA) and CT arterioportography (CTAP) using 16-slice multidetector CT. Materials: Twenty-nine patients with 50 HCCs underwent sequentially acquired double-contrast MRI-gadobenate dimeglumine-enhanced dynamic MRI and Resovist-enhanced MRI-and combined CTHA and CTAP using 16-slice multidetector CT. Dynamic MRI was obtained using volumetric interpolated technique and sensitivity encoding on a 1.5-T unit. Resovist-enhanced MRI was composed of T2-weighted turbo spin-echo and T2*-weighted gradient echo sequences. Sensitivity, positive predictive value, and diagnostic accuracy for double-contrast MRI, gadolinium-enhanced MRI, and combined CTHA and CTAP were calculated by 2 observers using an alternative-free response receiver operating characteristic analysis. Results: For all observers, the Az values of double-contrast MRI (mean, 0.96) and combined CTHA and CTAP (mean, 0.93) were similar, which tended to be better than that of gadolinium-enhanced MRI (mean, 0.91). The sensitivity of double-contrast MRI (mean, 93%) and combined CTHA and CTAP (mean, 92%) was equivalent for all observers, which was better than that of gadolinium-enhanced MRI (mean, 85%; P < 0.05). The positive predictive value of double-contrast MRI was better than that of combined CTHA and CTAP (P < 0.05). Conclusion: The sequentially acquired double-contrast MRI and combined CTHA and CTAP showed a similar diagnostic accuracy and sensitivity for detecting HCC.

High-resolution Magnetic Resonance Imaging of Symptomatic Middle Cerebral Artery Dissection

Dissection of the middle cerebral artery (MCA) is less frequent compared with dissection of vessels in the vertebrobasilar system or dissection of the carotid artery. High-resolution cross-sectional magnetic resonance imaging (HRMRI) has emerged as a potential technique for atherosclerotic plaque imaging in MCA. We enrolled 3 patients with MCA dissection on whom HRMRI was performed for evaluation of MCA stenosis. Two patients had an embolic infarction in the MCA territory and focal dissection. One patient had a massive infarction in the MCA territory and long-segment dissection of the MCA. On HRMRI, our objectives had an intimal flap with patency of the lumen and 1 had extensive hemorrhaging in the false lumen.

CT findings of mild forms or early manifestations of acute cholecystitis

OBJECTIVE The objective of this study was to determine the most predictive CT feature of the mild forms or early manifestations of acute cholecystitis. MATERIALS AND METHODS Two radiologists analyzed CT of 34 patients with mild or early acute cholecystitis and 34 control patients for pericholecystic increased attenuation on the arterial phase, indistinctness of the interface between the gallbladder (GB) and the liver, enhancement of the GB wall, and increased attenuation of the GB bile. RESULTS There were significant differences in the mean values for each CT feature but increased attenuation of the GB bile between patients and control group (P<.05). The most significant predictor of mild or early acute cholecystitis on CT was the presence of pericholecystic increased attenuation on the arterial phase (sensitivity, 82.4%), followed by indistinctness of the interface between the GB and liver (sensitivity, 38.0%), which were identified by both observers with good agreement (kappa=0.735 and kappa=0.687). CONCLUSIONS The pericholecystic increased attenuation on arterial phase CT was the most significant predictor of mild forms or early manifestations of acute cholecystitis.

Detection of intracranial aneurysms using three-dimensional multidetector-row CT angiography: is bone subtraction necessary?

PURPOSE The aim of this study was to evaluate the usefulness of three-dimensional CT angiography (3D CTA) with bone subtraction in a comparison with 3D CTA without bone subtraction for the detection of intracranial aneurysms. MATERIALS AND METHODS Among 337 consecutive patients who had intracranial aneurysms detected on 3D CTA, 170 patients who underwent digital subtraction angiography (DSA) were included in the study. CTA was performed with a 16-slice multidetector-row CT (MDCT) scanner. We created the 3D reconstruction images with and without bone subtraction by using the volume rendering technique. Three neuroradiologists in a blinded fashion interpreted both 3D CTA images with and without bone subtraction. The diagnostic accuracy of both techniques was evaluated using the alternative free-response receiver operating characteristic (ROC) analysis. The sensitivity and positive predictive value were also evaluated. RESULTS A total of 200 aneurysms (size: 2-23 mm) were detected in 170 patients. The area under the receiver operating characteristic curve (Az) for 3D CTA with bone subtraction (mean, Az=0.933) was significantly higher than that for 3D CTA without bone subtraction (mean, Az=0.879) for all observers (P<0.05). The sensitivity of 3D CTA with bone subtraction for three observers was 90.0, 92.0 and 92.5%, respectively, while the sensitivity of 3D CTA without bone subtraction was 83.5, 83.5 and 87.5%, respectively. No significant difference in positive predictive value was observed between the two modalities. CONCLUSIONS 3D CTA with bone subtraction showed significantly higher diagnostic accuracy for the detection of intracranial aneurysms as compared to 3D CTA without bone subtraction.

Manual Aspiration Thrombectomy Using Penumbra Catheter in Patients with Acute M2 Occlusion : A Single-Center Analysis.

Objective The efficacy and safety of manual aspiration thrombectomy using Penumbra in an acute occlusion of large intracranial arteries has been proven in many previous studies. Our study aimed to retrospectively assess the efficacy and safety of manual aspiration thrombectomy using Penumbra in patients with small vessel occlusions (M2 segment of the MCA). Methods We conducted a retrospective review of 32 patients who underwent manual aspiration thrombectomy using the Penumbra 4 MAX Reperfusion Catheter for treatment of an M2 occlusion between January 2013 and November 2014. We evaluated immediate angiographic results and clinical outcomes through review of patient electronic medical records. Results There were slightly more men in this study (M : F=18 : 14) and the median age was 72.5 (age range : 41–90). The rate of successful recanalization (TICI grade ≥2b) was 84% (27/32). NIHSS at discharge and favorable clinical outcomes at 3 months were significantly improved than baseline. Median initial NIHSS score was 10 (range : 4–25) and was 4 (range : 0–14) at discharge. Favorable clinical outcomes (mRS score ≤2 at 3 months) were seen in 25 out of 32 patients (78%). There were no procedure-related symptomatic intracerebral hemorrhages. One patient expired after discharge due to a cardiac problem. Conclusion Manual aspiration thrombectomy might be safe and is capable of achieving a high rate of successful recanalization and favorable clinical outcomes in patients with distal cerebral vessel occlusion (M2).