Enhancements in hepatobiliary imaging: the spectrum of gadolinium-ethoxybenzyl diethylenetriaminepentaacetic acid usages in hepatobiliary magnetic resonance imaging.

Gadolinium-ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a unique hepatocyte-specific contrast agent approved for clinical use in the United States in 2008. Gd-EOB-DTPA-enhanced MR has shown to improve detection and characterization of hepatic lesions. Gd-EOB-DTPA is now being routinely used in daily clinical practice worldwide. Therefore, it is important for radiologists to be familiar with the potential uses and pitfalls of Gd-EOB-DTPA, which extends beyond the assessment of focal hepatic lesions. The purpose of this article is to review the various usages of Gd-EOB-DTPA in hepatobiliary MR imaging.

Tender Cystic Structure on the Back in an Infant.

A 1-year-old Hispanic boy with multiple congenital anomalies including a double-outlet right ventricle, significant scoliosis, kyphosis, and multiple hemivertebrae and hemilamina presented with recurrent febrile episodes. He was found to have Staphylococcus epidermidis meningitis, which persisted despite medical management. On physical examination, a 1×1-cm, tender, erythematous cystic structure with a purulent focus was discovered on the upper portion of his back (Figure 1). His mother noted that the structure was not present at birth, but there was a small red area at the time of delivery that had slowly developed into the lesion shown. T2-weighted sagittal magnetic resonance imaging showed a 4-mm sinus connection from the superficial cystic structure (white arrow) to another 2.4×1.5-cm cystic structure (black arrow) at the level of the hemivertebrae (Figure 2).

Gadoxetate Disodium-Enhanced MRI to Differentiate Dysplastic Nodules and Grade of Hepatocellular Carcinoma: Correlation With Histopathology.

OBJECTIVE: The objective of our study was to determine quantitative differences to differentiate low-grade from high-grade dysplastic nodules (DNs) and low-grade from high-grade hepatocellular carcinomas (HCCs) using gadoxetate disodium-enhanced MRI. MATERIALS AND METHODS: A retrospective study of 149 hepatic nodules in 127 consecutive patients who underwent gadoxetic acid-enhanced MRI was performed. MRI signal intensities (SIs) of the representative lesion ROI and of ROIs in liver parenchyma adjacent to the lesion were measured on unenhanced T1-weighted imaging and on dynamic contrast-enhanced MRI in the arterial, portal venous, delayed, and hepatobiliary phases. The relative SI of the lesion was calculated for each phase as the relative intensity ratio as follows: [mass SI / liver SI]. RESULTS: Of the 149 liver lesions, nine (6.0%) were low-grade DNs, 21 (14.1%) were high-grade DNs, 83 (55.7%) were low-grade HCCs, and 36 (24.2%) were high-grade HCCs. The optimal cutoffs for differentiating low-grade DNs from high-grade DNs and HCCs were an unenhanced to arterial SI of ≥ 0 or a relative SI on T2-weighted imaging of ≤ 1.5, with a positive predictive value (PPV) of 99.2% and accuracy of 88.6%. The optimal cutoffs for differentiating low-grade HCCs from high-grade HCCs were a relative hepatobiliary SI of ≤ 0.5 or a relative T2 SI of ≥ 1.5, with a PPV of 81.0% and an accuracy of 60.5%. CONCLUSION: Gadoxetate disodium-enhanced MRI allows quantitative differentiation of low-grade DNs from high-grade DNs and HCCs, but significant overlap was seen between low-grade HCCs and high-grade HCCs.

Efficacy of the American Association for the Study of Liver Disease and Barcelona criteria for the diagnosis of hepatocellular carcinoma.

OBJECTIVES: Dynamic contrast-enhanced CT scan and MRI are essential for preoperative diagnosis of hepatocellular carcinoma (HCC), using the established Barcelona and AASLD criteria, which have been validated in only a few reports. The aim of this study is to retrospectively assess the diagnostic performance of these criteria in diagnosing or excluding HCC in at-risk patients with histopathology confirmation. METHODS: After institutional review board approval, a HIPAA compliant study was performed. The study cohort consisted of 156 de novo hepatic nodules imaged by either dynamic contrast-enhanced CT or MRI within 90 days of histopathology. Images were retrospectively reviewed by two abdominal radiologists blinded to clinical details, and all nodules were categorized as either meeting or not meeting AASLD and Barcelona criteria. By AASLD or Barcelona criteria, HCC was defined as any nodule greater than or equal to 1 or 2 cm, respectively, with hyperenhancement relative to background liver on arterial phase and hypoenhancement relative to background liver on portal venous or delayed phases. Significant differences in cohorts were analyzed using chi squared analysis (p < 0.05). RESULTS: On biopsy, 141/156 (90.38%) nodules were diagnosed as HCC. The respective sensitivity, specificity, accuracy and positive predictive value of AASLD and Barcelona were 78.7% and 63.1% (sensitivity), 73.3% and 86.7% (specificity), 78.2% and 65.4% (accuracy), and 82% and 63% (positive predictive value) (p < 0.001). CONCLUSIONS: Using established imaging criteria, up to 21.8% of presumed HCC nodules are inaccurately characterized and many small HCC nodules remain undiagnosed.

Diffusion-weighted imaging of the abdomen at 3 T: image quality comparison with 1.5-T magnet using 3 different imaging sequences.

OBJECTIVE: This study aimed to perform comparisons between diffusion-weighted imaging (DWI) sequences at 3 T with 1.5 T. METHODS: Thirteen healthy volunteers underwent abdominal DWI on both 3- and 1.5-T magnets using 3 sequences including breath hold without parallel imaging (PI), breath hold with PI, and free breathing with PI at b50 and b1000. Artifacts and subjective image quality scores, signal intensity, and apparent diffusion coefficient were compared. RESULTS: For breath hold without PI, higher artifact was noted at 3 T b50 compared with 1.5 T (P < 0.0001). For b50 and b1000 breath hold with PI, artifacts were not different between the magnets, but image quality was better at 3 T (P = 0.04 and P = 0.02, respectively). For b50 and b1000 free breathing sequences, artifact and image quality scores were significantly better at 1.5 T. For breath hold acquisitions, the signal-to-noise ratio of gallbladder, kidneys, and pancreas was generally higher and that of the liver was lower on 3 T. Imaging at 3 T showed significantly higher image quality and lower artifacts for breath hold with PI compared with free breathing. Most apparent diffusion coefficients were not significantly different between the 2 magnets (P > 0.05). CONCLUSIONS: Three-tesla magnets can provide good images using breath hold with PI sequence.

Coronary venous aneurysm in patients without cardiac arrhythmia as detected by MDCT: an anatomic variant or a pathologic entity.

OBJECTIVES: The aim of this study was to determine the prevalence of coronary venous aneurysm in patients with no history of cardiac arrhythmia using 64-slice multidetector computed tomography. BACKGROUND: Coronary vein aneurysm frequently has been reported in association with cardiac arrhythmias such as ventricular pre-excitation. METHODS: Coronary computed tomography angiograms of 187 patients (108 men, 79 women; mean age +/- SD, 60 +/- 12 years) were analyzed retrospectively for the presence of a focal coronary venous aneurysm. Fusiform aneurysm was defined as a focal dilatation of twice the normal vein. However, any size of diverticular aneurysms was included. Cross-sectional diameters of normal and aneurysmal segments of the posterior interventricular vein, great cardiac vein, and coronary sinus (CS) were measured at mid-diastole, late systole, and atrial systole. The Student t test was used for continuous variables and contingency tables were used for categorical variables. RESULTS: A single aneurysm was found in 19 (10%) patients (fusiform, n =16; diverticular, n = 3). The most common anatomic location was the posterior interventricular vein near the confluence with the CS (n = 14), followed by the great cardiac vein near the junction with the CS (n = 3), and the CS (n = 2). The mean diameter of the aneurysms was 9.3 +/- 1.2 mm (range, 8.1 to 11.4 mm) at mid-diastole and 10.4 +/- 1.4 mm (range, 8.5 to 12.7 mm) at late systole. However, the difference was not statistically significant. All normal CSs and 1 aneurysm arising from the CS showed contraction during atrial systole, which may suggest atrial myocardial coverage of these structures. Patients with a venous aneurysm were significantly older than patients without an aneurysm (67.6 +/- 11 vs. 59 +/- 12 years, respectively; p = 0.006). CONCLUSIONS: Coronary vein aneurysms (especially the fusiform type) were seen in up to 10% of patients with no history of cardiac arrhythmia and can be well visualized on computed tomography angiograms.

Prevalence of left atrial appendage pseudothrombus filling defects in patients with atrial fibrillation undergoing coronary computed tomography angiography.

BACKGROUND: Previous reports have shown that computed tomography (CT) is a useful, noninvasive test for detecting atrial thrombi. However, blood stasis in the left atrial appendage (LAA) of patients with atrial fibrillation (AF) may be a common cause for false-positive results. OBJECTIVES: We retrospectively evaluated the prevalence of filling defects that may simulate thrombus in the LAA of patients with AF during routine coronary CT angiography (CTA). METHODS: The LAA of 7 patients with AF was studied for the presence of filling defects and compared with 250 healthy persons. LAA volume in the patients with AF was measured at 10 different cardiac phases and compared with 30 healthy patients. RESULTS: Of the 7 patients with AF studied with CTA, 5 were positive for LAA filling defects. Follow-up imaging studies, including transesophageal echocardiogram, contrast-enhanced magnetic resonance angiography, or delayed-CT, were negative for LAA thrombus. Of 250 patients without AF, CTA showed no evidence of LAA filling defects. Patients with AF had significantly larger LAA volumes at all cardiac phases measured compared with patients without AF (15.2 +/- 6.93 mL compared with 6.85 +/- 3.01 mL at atrial contraction [P = 0.0187], 17.4 +/- 7.76 mL compared with 9.46 +/- 3.43 mL at ventricular systole [P = 0.0351], and 14.5 +/- 5.87 mL compared with 8.48 +/- 3.10 mL at mid-diastole [P = 0.0341]). Compared with the healthy persons, the patients with AF showed reduced percentages of change in LAA volume when the atrial contraction phase was compared with other phases: 44.0% +/- 25.6% compared with 16.5% +/- 12.2% compared with ventricular systole (P = 0.0004) and 29.5% +/- 23.7% compared with -1.63% +/- 8.84% at mid-diastole (P < 0.0001). CONCLUSIONS: Pseudothrombus filling defects are common in the LAA of patients with AF undergoing coronary CTA and should not be mistaken for real thrombus.

Multidetector computed tomography shows intramyocardial fat deposition.

BACKGROUND: Intramyocardial fat deposition occurs as an age-related process and in multiple pathologic processes. OBJECTIVE: We evaluated the presence of left ventricular (LV) and right ventricular (RV) intramyocardial fat with 64-slice multidetector computed tomography (MDCT). METHODS: One hundred persons with no history of coronary artery disease (47 women, 53 men; mean age [+/- SD], 53 +/- 12.2 years) and 25 patients with CT findings of myocardial infarction (17 men, 8 women; mean age, 71.3 +/- 9.6 years) were studied for intramyocardial fat in defined segments of the ventricles (17 LV and 10 RV segments) at 3 levels. Fat deposition was defined as density range of -30 to -190 Hounsfield units on images both before and after contrast. RESULTS: In healthy persons, LV intramyocardial fat was primarily located in the basal segments (5% anteroseptal, 5% inferior), and RV intramyocardial fat was primarily located in the anterolateral (24% of base, 23% of mid) and inferolateral (27% base, 27% mid) segments. Older age was associated with an increased odds of RV (sex-adjusted odds ratio [OR] per decade increment, 1.61; 95% confidence interval [CI], 1.11-2.33; P = 0.012) but not LV (OR, 0.97; 95% CI, 0.67-1.40; P = 0.85) intramyocardial fat. Compared with women, men had a lower risk of LV (95% CI, 0.1-0.64; P = 0.004) but not RV (95% CI, 0.35-1.87; P = 0.62) intramyocardial fat. Patients with old myocardial infarction (>3 years) had increased percentage of fat in infarcted left ventricles at all 3 levels (P

Imaging of patent foramen ovale with 64-section multidetector CT.

PURPOSE: To investigate the feasibility of 64-section multidetector computed tomography (CT) by using CT angiography (a) to demonstrate anatomic detail of the interatrial septum pertinent to the patent foramen ovale (PFO), and (b) to visually detect left-to-right PFO shunts and compare these findings in patients who also underwent transesophageal echocardiography (TEE). MATERIALS AND METHODS: In this institutional review board-approved HIPAA-compliant study, electrocardiographically gated coronary CT angiograms in 264 patients (159 men, 105 women; mean age, 60 years) were reviewed for PFO morphologic features. The length and diameter of the opening of the PFO tunnel, presence of atrial septal aneurysm (ASA), and PFO shunts were evaluated. A left-to-right shunt was assigned a grade according to length of contrast agent jet (grade 1, 1 cm to 2 cm; grade 3, >2 cm). In addition, 23 patients who underwent both modalities were compared (Student t test and linear regression analysis). A difference with P < .05 was significant. RESULTS: A flap valve, seen in 101 (38.3%) patients, was patent at the entry into the right atrium (PFO) in 62 patients (61.4% of patients with flap valve, 23.5% of total patients). A left-to-right shunt was detected in 44 (16.7% of total) patients (grade 1, 61.4%; grade 2, 34.1%; grade 3, 4.5%). No shunt was seen in patients without a flap valve. Mean length of PFO tunnel was 7.1 mm in 44 patients with a shunt and 12.1 mm in 57 patients with a flap valve without a shunt (P < .0001). In patients with a tunnel length of 6 mm or shorter, 92.6% of the shunts were seen. ASA was seen in 11 (4.2%) patients; of these patients, a shunt was seen in seven (63.6%). In 23 patients who underwent CT angiography and TEE, both modalities showed a PFO shunt in seven. CONCLUSION: Multidetector CT provides detailed anatomic information about size, morphologic features, and shunt grade of the PFO. Shorter tunnel length and septal aneurysms are frequently associated with left-to-right shunts in patients with PFO.

Bachmann Bundle and its arterial supply: imaging with multidetector CT--implications for interatrial conduction abnormalities and arrhythmias.

PURPOSE: To retrospectively investigate anatomy of Bachmann Bundle (BB) and its vascular supply at 64-section multidetector computed tomography (CT) in healthy patients and patients with abnormalities. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and waived informed consent. Clinical histories, electrocardiograms (ECGs), and coronary 64-section multidetector CT angiograms in 317 patients were reviewed (healthy group, 164; group with abnormalities, 153). Among patients with abnormalities, 68 had atrial fibrillation (AF) or interatrial conduction block (IAB) (P wave duration, >or=120 msec), 46 had severe coronary artery disease (CAD) (>or=70% stenosis of coronary artery giving rise to sinuatrial node [SAN] artery), and 39 had severe CAD and an abnormal ECG (AF or IAB). Length, anteroposterior and superoinferior diameters, attenuation, and vascular supply of BB were studied. Student t test for continuous variables and contingency tables for categorical variables were used. RESULTS: BB was visualized, to greater degree, in the healthy group (90.2% vs 73.9% for group with abnormalities, P < .001). Visualization of BB was similar among subgroups with abnormalities: 71.7% in patients with severe CAD, 73.5% in patients with abnormal ECG, and 76.9% in patients with severe CAD and abnormal ECG. BB measurements were similar for both groups. Patients with nonvisualized BB displayed lower overall mean attenuation in the region, with -30.6 HU +/- 33.4 (standard deviation), but mean attenuation in healthy patients was 51.3 HU +/- 59.9 (P < .001). This finding suggests fatty infiltration. BB and BB region were mainly supplied by the right SAN artery (55.5%), followed by the left SAN artery (39.6%) and both SAN arteries (4.9%). In the group with abnormalities, there was a significant difference for SAN artery nonvisualization between those with and without identifiable BB (P = .001). CONCLUSION: BB and its vascular supply can easily be demarcated on cardiac CT images. BB was visualized less in patients with severe CAD and abnormal ECG, a finding that suggests that disease of BB fibers may play a role in development of atrial arrhythmias.

MDCT of the S-shaped sinoatrial node artery.

OBJECTIVE: The purpose of this study was to use 64-MDCT to investigate the anatomic characteristics of the S-shaped variant of the sinoatrial node (SAN) artery and to describe the clinical implications of the findings in ablative procedures involving the left atrium. MATERIALS AND METHODS: Coronary CT angiograms of 250 patients (152 men, 98 women; mean age, 60 +/- 12 [SD] years) were retrospectively analyzed for identification of the origin, number, anatomic course, mode of termination, and S-shaped variant of the SAN artery. RESULTS: At least one SAN artery was detected in 244 patients. The S-shaped variant was seen in 35 (14.3%) of these patients. Thirty-four of the variants (30.6% of all left SAN arteries) arose from the proximal to middle portion of the left circumflex artery (mean distance between the ostium of the left circumflex artery and the origin of S-shaped variant, 28.7 +/- 13.1 mm). The other variant (0.7% of all right SAN arteries) originated from the distal right coronary artery. The S-shaped variant was the only artery supplying the SAN in 28 (11.4%) of the patients. In patients with two arteries supplying the SAN, the right SAN artery and the S-shaped variant of the left SAN artery were seen together in seven patients. The S-shaped SAN artery (mean distance from atrial wall, 2.43 +/- 0.992 mm) had a predictable proximal course, lying in the posterior aspect in a groove between the orifices of the left superior pulmonary vein and the left atrial appendage close to the left atrial wall. The terminal segment of the artery approached the nodal tissue posterior to the superior vena cava in 22 patients, anterior to the vena cava in 10 patients, and through branches surrounding the vena cava in two patients. CONCLUSION: The S-shaped variation of the SAN artery is common and has a characteristic anatomic course. MDCT can be used to plan surgical and catheter-based left atrial interventions in which this artery is at risk of injury.