Sung Soo Ahn

Added Value of Gadoxetic Acid-enhanced Hepatobiliary Phase MR Imaging in the Diagnosis of Hepatocellular Carcinoma

PURPOSE To determine the added value of hepatobiliary phase images in gadoxetic acid-enhanced magnetic resonance (MR) imaging in the evaluation of hepatocellular carcinoma (HCC). MATERIALS AND METHODS Institutional review board approved this retrospective study and waived the informed consent. Fifty-nine patients with 84 HCCs underwent gadoxetic acid-enhanced MR examinations that included 20-minute delayed hepatobiliary phase imaging. MR imaging was performed with a 1.5-T system in 19 patients and a 3.0-T system in 40 patients. A total of 113 hepatic nodules were documented for analysis. Three radiologists independently reviewed two sets of MR images: set 1, unenhanced (T1- and T2-weighted) and gadoxetic acid-enhanced dynamic images; set 2, hepatobiliary phase images and unenhanced and gadoxetic acid-enhanced dynamic images. For each observer, the diagnostic accuracy was compared by using the area under the alternative free-response receiver operating characteristic curve (A(z)). Sensitivity and specificity were also calculated and compared between the two sets. RESULTS For all observers, A(z) values were higher with the addition of the hepatobiliary phase. The observer who had the least experience in abdominal imaging (2 years) demonstrated significant improvement in A(z), from 0.895 in set 1 to 0.951 in set 2 (P = .049). Sensitivity increased with the addition of hepatobiliary phase images but did not reach statistical significance. Nine HCCs (10.7%) in six patients (10.1%) were seen only on hepatobiliary phase images. CONCLUSION Hepatobiliary phase images obtained after gadoxetic acid-enhanced dynamic MR imaging may improve diagnosis of HCC and assist in surgical planning.

Outcomes and prognostic factors of intracranial unruptured vertebrobasilar artery dissection

Objective: We aimed to evaluate the long-term clinical outcomes and prognostic factors of symptomatic intracranial unruptured vertebrobasilar artery dissection (siu-VBD). Methods: A total of 191 patients (M:F = 127:64; median age, 46 years) with siu-VBD were treated between January 2001 and December 2008. Presentations, treatments, outcomes, and prognostic factors were retrospectively analyzed. Results: Clinical manifestations were ischemic symptoms with headache (n = 97) or without headache (n = 13) and headache without ischemic symptoms (n = 81). Forty-six patients (24.1%) underwent endovascular treatment. The remaining 145 patients (75.9%) were medically treated with anticoagulants (n = 49), antiplatelets (n = 48), or analgesics alone (n = 48). Clinical follow-up data were available in 178 patients (102 ischemic and 76 nonischemic) at 15 to 102 months (mean, 46 months). None of the siu-VBD hemorrhaged. All 76 patients without ischemic presentation had favorable outcomes (modified Rankin Scale, 0–1). Of the 102 patients with ischemic presentation, outcomes were favorable in 92 and unfavorable in 10 patients. Four patients died; 3 died of causes unrelated to VBD, and one died as a result of basilar artery (BA) dissection. Old age (odds ratio [OR] 1.099; 95% confidence interval [CI] 1.103–1.204; p = 0.042) and BA involvement (OR 11.886; 95% CI 1.416–99.794; p = 0.023) were independent predictors of unfavorable outcomes in siu-VBD with ischemic presentation. Conclusions: Clinical outcomes for siu-VBD were favorable in all patients without ischemic symptoms and in most patients with ischemic presentation. None of the siu-VBD caused subarachnoid hemorrhage. Old age and BA involvement were independent predictors of unfavorable outcome in siu-VBD with ischemic presentation.

Biopsy of Thyroid Nodules: Comparison of Three Sets of Guidelines

OBJECTIVE The purpose of this study was to compare the results with three sets of guidelines for fine-needle aspiration biopsy of thyroid nodules. MATERIALS AND METHODS A total of 1,398 nodules confirmed with fine-needle aspiration biopsy or surgery were included in the study. We compared the diagnostic value of three sets of guidelines for ultrasound findings that should lead to fine-needle aspiration biopsy of a nodule. According to the Kim criteria, a nodule should have at least one of the following findings: marked hypoechogenicity, irregular or microlobulated margins, microcalcifications, or length greater than width. According to the Society of Radiologists in Ultrasound, biopsy should be performed on a nodule 1 cm in diameter or larger with microcalcifications, 1.5 cm in diameter or larger that is solid or has coarse calcifications, and 2 cm in diameter or larger that has mixed solid and cystic components, and a nodule that has undergone substantial growth or is associated with abnormal cervical lymph nodes. According to the American Association of Clinical Endocrinologists, a hypoechoic nodule with at least one additional feature, such as irregular margins, length greater than width, and microcalcifications, should be biopsied. RESULTS For all nodules, the diagnostic accuracy of the Kim (area under the receiver operating characteristic curve [Az]=0.868) and American Association of Clinical Endocrinologists (Az=0.850) criteria was greater than that of the Society of Radiologists in Ultrasound criteria (Az=0.551). The number of nodules for which fine-needle aspiration biopsy was recommended (25.6%) was smallest with use of the American Association of Clinical Endocrinologists criteria, and the smallest number (7.3%) of missed malignant lesions was associated with use of the Kim criteria. The results did not change for the subgroup with nodules larger than 1 cm. CONCLUSION The Kim and American Association of Clinical Endocrinologists criteria are more accurate than the Society of Radiologists in Ultrasound criteria. The American Association of Clinical Endocrinologists guidelines are recommended for achieving high specificity, and the Kim criteria may be chosen for higher sensitivity.

Parathyroid incidentalomas detected on routine ultrasound-directed fine-needle aspiration biopsy in patients referred for thyroid nodules and the role of parathyroid hormone analysis in the samples.

Many patients who have undergone surgical treatment for thyroid cancer are treated with postoperative radioactive iodine ablation. Thyroid hormone is generally stopped for several weeks prior to treatment. We report the case of a woman on long-standing treatment with lithium for bipolar disorder who, after 3 weeks of withdrawal from thyroid hormone, presented to the hospital with severe lithium toxicity. She required admission to the intensive care unit and was treated with hemodialysis and supportive care with resolution of her illness. In this patient, renal dysfunction associated with her hypothyroid state was likely the precipitating event leading to the lithium toxicity. We review the effect of hypothyroidism on renal function and the association of hypothyroidism with drug toxicities. This case illustrates the potential for hypothyroid-induced renal dysfunction to lead to adverse clinical consequences in patients taking medications cleared by the kidneys.

Glioma grading capability: comparisons among parameters from dynamic contrast-enhanced MRI and ADC value on DWI.

Objective Permeability parameters from dynamic contrast-enhanced MRI (DCE-MRI) and apparent diffusion coefficient (ADC) value on diffusion-weighted imaging (DWI) can be quantitative physiologic metrics for gliomas. The transfer constant (Ktrans) has shown efficacy in grading gliomas. Volume fraction of extravascular extracellular space (ve) has been underutilized to grade gliomas. The purpose of this study was to evaluate ve in its ability to grade gliomas and to assess the correlation with other permeability parameters and ADC values. Materials and Methods A total of 33 patients diagnosed with pathologically-confirmed gliomas were examined by 3 T MRI including DCE-MRI and ADC map. A region of interest analyses for permeability parameters from DCE-MRI and ADC were performed on the enhancing solid portion of the tumors. Permeability parameters form DCE-MRI and ADC between low- and high-grade gliomas; the diagnostic performances of presumptive metrics and correlation among those metrics were statistically analyzed. Results High-grade gliomas showed higher Ktrans (0.050 vs. 0.010 in median value, p = 0.002) and higher ve (0.170 vs. 0.015 in median value, p = 0.001) than low-grade gliomas. Receiver operating characteristic curve analysis showed significance in both Ktrans and ve for glioma grading. However, there was no significant difference in diagnostic performance between Ktrans and ve. ADC value did not correlate with any of the permeability parameters from DCE-MRI. Conclusion Extravascular extracellular space (ve) appears to be comparable with transfer constant (Ktrans) in differentiating high-grade gliomas from low-grade gliomas. ADC value does not show correlation with any permeability parameters from DCE-MRI.

CT Detection of Subendocardial Fat in Myocardial Infarction

OBJECTIVE We sought to systemically analyze the characteristics of fat accumulation in patients with myocardial infarction (MI) relative to various clinical parameters. MATERIALS AND METHODS We included 161 patients (129 men, 32 women; mean age, 60.7 years) who had previously been diagnosed with MI and had undergone CT coronary angiography between February 2003 and April 2005. We analyzed the characteristics of myocardial fat, if present, and compared the clinical parameters of the patients with and those without myocardial fat. RESULTS Myocardial fat was found in the subendocardial region in 36 (22.4%) patients with MI. In all cases, the myocardial fat was located in the subendocardial region and was typically detected in the left anterior descending artery territory (75%, n = 27). The mean attenuation value of myocardial fat was -29.6 HU on unenhanced CT. Myocardial fat was more frequently associated with a greater infarct age, milder coronary artery stenosis, and fewer number of diseased vessels. Patients with myocardial fat had more severe regional wall motion abnormalities on follow-up echocardiography. Age, sex, the presence of ST elevation or Q wave, elevated levels of cardiac enzymes, ejection fraction, and end-diastolic left ventricular dimension on follow-up echocardiography, as well as the presence of arrhythmia, were not significantly different between the two groups. CONCLUSION Myocardial fat was detected in 22.4% of MI patients and was more frequently associated with a longer postinfarct period, milder coronary artery stenosis, fewer number of diseased vessels, and more severe regional wall motion abnormalities.

Spontaneous Symptomatic Intracranial Vertebrobasilar Dissection: Initial and Follow-up Imaging Findings

PURPOSE To evaluate initial radiologic findings of symptomatic intracranial vertebrobasilar dissections (VBDs) as well as the results at follow-up imaging of dissections that are conservatively managed. MATERIALS AND METHODS The respective institutional review boards approved this retrospective study and waived the need for informed consent. The initial radiologic findings of 210 patients with 230 symptomatic intracranial VBDs were retrospectively evaluated (48 ruptured, 182 unruptured). Those patients had undergone conventional angiography as well as magnetic resonance imaging and/or computed tomographic angiography, so that angiographic shapes and pathognomonic findings (eg, intramural hematoma, intimal flap) could be reviewed. The primary angiographic shapes of the symptomatic intracranial VBDs were subdivided into three groups: (a) dilatation without stenosis, (b) pearl-and-string, and (c) stenosis without dilatation. Furthermore, the radiologic evolution of conservatively managed symptomatic intracranial VBDs was evaluated. The respective frequencies of the radiologic findings at initial and follow-up imaging studies were compared by using χ2 tests. RESULTS Primary shape differed significantly between ruptured and unruptured symptomatic intracranial VBDs. Most ruptured dissections presented with one of two main structures: dilatation without stenosis or pearl-and-string appearance. The primary shape of unruptured dissections was evenly distributed among the three types of findings. Intramural hematomas were most frequently found in the stenosis-without-dilatation group (42 of 60 [70%]), followed by the pearl-and-string group (27 of 90 [30%]). Intimal flap was most frequently found in the pearl-and-string group (21 of 90 [23%]), followed by the stenosis-without-dilatation group (eight of 60 [13%]). Follow-up results significantly differed by initial VBD shapes: Seventy-four percent (25 of 34) of the dilatation-without-stenosis group showed no change, whereas improvement was observed in 91% (39 of 43) of the stenosis-without-dilatation group (P<.05). Intracranial VBDs with intramural hematoma showed improvement in 63% (34 of 54) of cases, progression occurred in 20% (11 of 54), and only 17% (nine of 54) exhibited no change (P<.05). CONCLUSION Primary angiographic shapes of symptomatic intracranial VBDs differed between ruptured and unruptured lesions. The stenosis-without-dilatation lesions most frequently exhibited radiologic improvement at follow-up imaging, followed by pearl-and-string and dilatation-without-stenosis lesions.

Indicative findings of pancreatic cancer in prediagnostic CT

We examined 20 prediagnostic CTs from 16 patients for whom the diagnosis of pancreatic cancer was delayed until full diagnostic CT was performed. Three radiologists independently reviewed the prediagnostic CTs along with 50 CTs of control subjects, including patients without pancreatic disease (n = 38) or with chronic pancreatitis without calcification visible on CT (n = 12). The reviewers recorded the presence of biliary or pancreatic ductal dilation, interruption of the pancreatic duct, distal parenchymal atrophy, contour abnormality and focal hypoattenuation. Frequency, sensitivity and specificity of the significant findings were calculated. Logistic regression analysis was performed. Findings indicative of pancreatic cancer were seen on 85% (17/20) of the prediagnostic CTs. Patients with pancreatic cancer were significantly (p < 0.05) more likely to show focal hypoattenuation, pancreatic duct dilation, interruption of the pancreatic duct, and distal parenchymal atrophy, with sensitivities and specificities of 75%/84%, 50%/78%, 45%/82% and 45%/96%, respectively. Focal hypoattenuation and distal parenchymal atrophy were the independent predictors of pancreatic cancer with odds ratios of 20.92 and 11.22, respectively. In conclusion, focal hypoattenuation and pancreatic duct dilation with or without interruption, especially when accompanied by distal parenchymal atrophy, were the most useful findings for avoiding delayed diagnosis of pancreatic cancer.

Prediction of methylguanine methyltransferase promoter methylation in glioblastoma using dynamic contrast-enhanced magnetic resonance and diffusion tensor imaging

OBJECT The methylation status of the methylguanine methyltransferase (MGMT) promoter has been associated with treatment response in glioblastoma. The authors aimed to assess whether MGMT methylation status can be predicted by dynamic contrast-enhanced (DCE) MRI and diffusion tensor imaging (DTI). METHODS This retrospective study included 43 patients with pathologically diagnosed glioblastoma who had undergone preoperative DCE-MRI and DTI and whose MGMT methylation status was available. The imaging features were qualitatively assessed using conventional MR images. Regions of interest analyses for DCE-MRI permeability parameters (transfer constant [Ktrans], rate transfer coefficient [Kep], and volume fraction of extravascular extracellular space [Ve]) and DTI parameters (apparent diffusion coefficient [ADC] and fractional anisotropy [FA]) were performed on the enhancing solid portion of the glioblastoma. Chi-square or Mann-Whitney tests were used to evaluate relationships between MGMT methylation and imaging parameters. The authors performed receiver operating characteristic curve analysis to find the optimal cutoff value for the presence of MGMT methylation. RESULTS MGMT methylation was not significantly associated with any imaging features on conventional MR images. Ktrans values were significantly higher in the MGMT methylated group (median 0.091 vs 0.053 min(-1), p = 0.018). However, Kep, Ve, ADC, and FA were not significantly different between the 2 groups. The optimal cutoff value for the presence of MGMT methylation was Ktrans > 0.086 min(-1) with an area under the curve of 0.756, a sensitivity of 56.3%, and a specificity of 85.2%. CONCLUSIONS Ktrans may serve as a potential imaging biomarker to predict MGMT methylation status preoperatively in glioblastoma; however, further investigation with a larger cohort is necessary.

Factors Affecting the Accuracy of Controlled Attenuation Parameter (CAP) in Assessing Hepatic Steatosis in Patients with Chronic Liver Disease

Background & Aims Controlled attenuation parameter (CAP) can measure hepatic steatosis. However, factors affecting its accuracy have not been described yet. This study investigated predictors of discordance between liver biopsy (LB) and CAP. Methods A total of 161 consecutive patients with chronic liver disease who underwent LB and CAP were enrolled prospectively. Histological steatosis was graded as S0 (<5%), S1 (5–33%), S2 (34–66%), and S3 (>66% of hepatocytes). Cutoff CAP values were calculated from our cohort (250, 301, and 325 dB/m for ≥S1, ≥S2, and S3). Discordance was defined as a discrepancy of at least two steatosis stages between LB and CAP. Results The median age (102 males and 59 females) was 49 years. Repartition of histological steatosis was as follows; S0 26.1% (n = 42), S1 49.7% (n = 80), S2 20.5% (n = 33), and S3 3.7% (n = 6). In multivariate linear regression analysis, CAP value was independently associated with steatosis grade along with body mass index (BMI) and interquartile range/median of CAP value (IQR/MCAP) (all P<0.05). Discordance was identified in 13 (8.1%) patients. In multivariate analysis, histological S3 (odd ratio [OR], 9.573; 95% confidence interval [CI], 1.207–75.931; P = 0.033) and CAP value (OR, 1.020; 95% CI, 1.006–1.034; P = 0.006) were significantly associated with discordance, when adjusting for BMI, IQR/MCAP, and necroinflammation, reflected by histological activity or ALT level. Conclusions Patients with high grade steatosis or high CAP values have a higher risk of discordance between LB and CAP. Further studies are needed to improve the accuracy of CAP interpretation, especially in patients with higher CAP values.