Two-Dimensional Spoiled Gradient-Recalled Echo Magnetic Resonance Imaging of the Liver Using Respiratory Navigator-Gating Techniques

imageObjective: We assessed the feasibility of T1-weighted 2-dimensional spoiled gradient-recalled (2D SPGR) acquisition in steady-state imaging of the liver with various respiratory navigator gating techniques.

Methods: A total of 12 healthy volunteers underwent in-phase and out-of-phase 2D SPGR imaging of the liver during breath-holding and free-breathing. Four techniques for respiratory navigation, 2 conventional navigator techniques and 2 self-navigator techniques, were used for free-breathing imaging.

Results: Good navigator waveforms were obtained in conventional navigation, whereas fluctuations were evident in self navigation. All of the 4 navigator-based methods provided better images in terms of background signals and visual image quality compared with images obtained with no respiratory control. However, differences remained in comparison with breath-holding. Superiority of self-navigation to conventional navigation was not shown.

Conclusions: Navigator-gating techniques improved 2D SPGR images of the liver acquired during free-breathing, suggesting feasibility and beneficial effects, although navigator-based images were still inferior to breath-hold images.

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Relationship of Nonseptal Late Gadolinium Enhancement to Ventricular Tachyarrhythmia in Hypertrophic Cardiomyopathy

imageObjective: This study aimed to determine the relationship between the extent and the location of late gadolinium enhancement (LGE) and ventricular tachyarrhythmia or implantable cardioverter defibrillator (ICD) in hypertrophic cardiomyopathy (HCM).

Methods: We enrolled 115 patients with HCM and LGE. The location of LGE was divided into septal and nonseptal segments. Clinical backgrounds and LGE were compared in patients between with and without the arrhythmia or consequent ICD installation.

Results: There were significant differences in the number of risk markers, left ventricular ejection fraction, extent of global LGE, and extent of nonseptal LGE between the groups (P

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Correlation Between Bile Reflux Gastritis and Biliary Excreted Contrast Media in the Stomach

imageObjective: This study aimed to evaluate the relationship between biliary excreted contrast media in the stomach and the presence of bile reflux gastritis.

Methods: Consecutive 111 patients who underwent both gadoxetic acid–enhanced magnetic resonance cholangiography (gadoxetic MRC) and gastric endoscopy were included in this study. We performed a review of the gadoxetic-MRC image sets acquired 60 minutes after intravenous injection of contrast media and endoscopic images. We recorded amount of contrast media in the stomach. The sensitivity, specificity, and accuracy of duodenogastric bile reflux diagnosis were evaluated for the gadoxetic MRC. Statistical analysis was performed using the Fisher exact test and the linear-by-linear association test.

Results: Among the 111 patients, 39 had 60-minute delayed images showing the presence of contrast media in the stomach. Of these 39 patients, 13 had bile reflux gastritis and 5 showed bile in the stomach without evidence of erythematous gastritis. Of the 72 patients who did not show contrast media in the stomach, none had bile reflux gastritis and 2 patients showed bile staining in the stomach without evidence of erythematous gastritis. Bile reflux gastritis was significantly more frequent in patients with contrast media in the stomach on gadoxetic MRC than in those without. Patients with high-grade extension of contrast media in the stomach had significantly frequent bile reflux gastritis than did those with low-grade extension.

Conclusion: Biliary excreted contrast media in the stomach on 60-minute delayed gadoxetic MRC has a correlation with the presence of bile reflux gastritis on endoscopic examination.

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Comparison of 270 Versus 320 mg I/mL of Iodixanol in 1 Image Assessment of Both Renal Arteries and Veins With Dual-Energy Spectral CT Imaging in Late Arterial Phase and Their Influence on Renal Function

imageObjective: The objective of this study was to compare the image quality of renal arteries and veins with dual-energy spectral computed tomography (CT) imaging in late arterial phase using 270 and 320 mg I/mL of iodixanol and their influence on renal function.

Methods: A total of 1062 patients underwent renal CT angiography with 270 or 320 mg I/mL of iodixanol with dual-energy spectral CT imaging in late arterial phase. Image quality and their influence on renal function were compared.

Results: There were no significant differences of CT value, signal-to-noise ratio, contrast-to-noise ratio, and subjective score of renal vessels between 2 groups (all P > 0.05). The incidence of contrast-induced nephropathy in patients with abnormal renal function using 320 mg I/mL of iodixanol was significantly higher than using 270 mg I/mL of iodixanol (P = 0.043).

Conclusions: The renal arteries and veins can be fully assessed in late arterial phase with 270 mg I/mL of iodixanol using dual-energy spectral CT scan with better preserved renal function.

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Preoperative Computed Tomography Assessment for Perinephric Fat Invasion: Comparison With Pathological Staging

imageObjective: The aim of this study was to assess the accuracy of computed tomography (CT) imaging in diagnosing perinephric fat (PNF) invasion in patients with renal cell carcinoma.

Methods: We retrospectively reviewed the medical records and preoperative CT images of 161 patients (105 men and 56 women) for pT1–pT3a renal cell carcinoma. We analyzed the predictive accuracy of CT criteria for PNF invasion stratified by tumor size. We determined the predictive value of CT findings in diagnosing PNF invasion using logistic regression analysis.

Results: The overall accuracy of perinephric (PN) soft-tissue stranding, peritumoral vascularity, increased density of the PNF, tumoral margin, and contrast-enhancing soft-tissue nodule to predict PNF invasion were 56%, 59%, 35%, 80%, and 87%, respectively. Perinephric soft-tissue stranding and peritumoral vascularity showed high sensitivity but low specificity regardless of tumor size. A contrast-enhancing soft-tissue nodule showed low sensitivity but high specificity in predicting PNF invasion. Among tumors 4 cm or less, PN soft-tissue stranding showed 100% sensitivity and 70% specificity, and tumor margin showed 100% sensitivity and 98% specificity. Among CT criteria for PNF invasion, PN soft-tissue stranding was chosen as the only significant factor for assessing PNF invasion by logistic regression analysis.

Conclusions: Computed tomography does not seem to reliably predict PNF invasion. However, PN soft-tissue stranding was shown to be the only significant factor for predicting PNF invasion, which showed good accuracy with high sensitivity and high specificity in tumors 4 cm or less.

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Dynamic Contrast-Enhanced Magnetic Resonance Imaging of Ocular Melanoma as a Tool to Predict Metastatic Potential

imagePurpose: This study explores the capability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to differentiate tumor characteristics of metastatic and nonmetastatic choroidal melanoma as a potential tool for patient management.

Materials and Methods: A total of 13 patients (69 ± 9 years) with choroidal melanoma were imaged using DCE-MRI on a 3-T MRI system with a 16-channel head coil. The Tofts 2-compartment model was chosen for quantification, and parameters Ktrans (the transfer constant from the blood plasma to the extracellular space) and Kep (the transfer constant from the extracellular space to the blood plasma) were calculated and compared. Metastasis was excluded by subsequent clinical work-up or confirmed by histology after targeted biopsy.

Results: Six patients were diagnosed with metastatic melanoma and 7 without. All orbital tumors were at least larger than 2 mm. A significant difference was identified in Ktrans between patients with (0.73 ± 0.18/min) and without (1.00 ± 0.21/min) metastatic melanoma (P = 0.03), whereas the difference was not significantly shown in Kep (2.58 ± 1.54/min of metastatic patients vs 2.98 ± 1.83/min of nonmetastatic patients, P = 0.67).

Conclusions: Dynamic contrast-enhanced magnetic resonance imaging has the potential to differentiate orbital melanomas with metastatic and nonmetastatic spread. Thus, DCE-MRI has the potential to be an in vivo imaging technique to predict early which patients are prone to metastatic disease.

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Computed Tomography Perfusion Following Transarterial Chemoembolization of Hepatocellular Carcinoma: A Feasibility Study in the Early Period

imageObjectives: The aim of this study was to assess the feasibility of computed tomography (CT) perfusion in early follow-up after transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC).

Methods: Fifteen patients with a total of 16 HCC who were referred to our institution for TACE were included in the study. Computed tomography perfusion was performed within 1 to 3 days before and 4 to 7 days after TACE. Multiphase contrast-enhanced CT was performed 35 (SD, 20) days after TACE. Hepatic arterial blood flow and portal venous blood flow, as well as the perfusion index (PI), were calculated for each HCC using the dual input maximum slope method. Visual grading of the PI and visual grading of the amount of deposition of embolic material within the HCC were performed using a 6-step scale. Differences in perfusion before and after TACE and correlation of perfusion before TACE with the amount of embolization material depositions 1 week and 1 month after TACE were tested.

Results: No statistically significant correlation was found between pre-TACE perfusion parameters and the amount of embolization material deposition in the post-TACE studies. There was no statistically significant difference between pre- and post-TACE arterial blood flow and portal venous blood flow, whereas PI was significantly lower after TACE. Congruently, visual grading of PI was statistically significantly lower after TACE. There was no statistically significant difference in quantitative pre-TACE and post-TACE PI between tumors, which showed hypervascularization in the multiphase follow-up CT and tumors that did not show hypervascularization. However, tumors that showed hypervascularization in the multiphase follow-up CT had significantly higher visual grading of PI after TACE than tumors that did not show hypervascularization.

Conclusions: Our findings indicate that visual interpretation of the PI of HCC derived from dual-input maximum slope CT perfusion may be an early predictor of response to TACE.

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Gastric Heterotopic Pancreas: Computed Tomography With Clinicopathologic Correlation

imageAbstract: Asymptomatic heterotopic pancreas (HP) is benign and can be monitored long term without further intervention. Heterotopic pancreas is sometimes surgically resected because it can be difficult to distinguish HP from neoplastic submucosal masses such as gastrointestinal stromal tumors. Although it is not very common, HP should be considered in the differential diagnosis when diagnosing extramucosal gastric masses to avoid unnecessary intervention. We review gastric HP with pathologic correlation to help with diagnosing HP on computed tomography.

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Intraluminal Uterine Hypodensity in CT Scans of Postmenopausal Women: Recommendations for Interpretation

imageObjective: This study aims to investigate the association between intraluminal uterine hypodensity and uterine malignancy and establish thresholds that would minimize routine gynecological evaluation.

Methods: Two groups were recruited retrospectively: cancer group, which comprised 32 sequential endometrial cancer patients, and postmenopausal group, which comprised 63 women, with no known gynecologic malignancy.

Two radiologists independently measured hypodensity, transversely in the axial plane and anterioposteriorly in the sagittal plane.

The association between cancer and hypodensity was evaluated. Receiver operating characteristic curves were evaluated diameters predictive of cancer.

Results: Hypodensity was associated with cancer (cancer group, 93.8% vs. postmenopausal group, 38.1%; P

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CT Attenuation of Pericoronary Adipose Tissue in Normal Versus Atherosclerotic Coronary Segments as Defined by Intravascular Ultrasound

imageBackground: The factors influencing genesis of atherosclerosis at specific regions within the coronary arterial system are currently uncertain. Local mechanical factors such as shear stress as well as metabolic factors, including inflammatory mediators released from epicardial fat, have been proposed. We analyzed computed tomographic (CT) attenuation of pericoronary adipose tissue in normal versus atherosclerotic coronary segments as defined by intravascular ultrasound (IVUS).

Patients and Methods: We evaluated the data sets of 29 patients who were referred for invasive coronary angiography and in whom IVUS of 1 coronary vessel was performed for clinical reasons. Coronary CT angiography was performed within 24 hours from invasive coronary angiography. Computed tomographic angiography was performed using dual-source CT (Siemens Healthcare; Forchheim, Germany). A contrast-enhanced volume data set was acquired (120 kV, 400 mA/rot, collimation 2 × 64 × 0.6 mm, 60–80 mL intravenous contrast agent). Intravascular ultrasound was performed using a 40-MHz IVUS catheter (Atlantis; Boston Scientific Corporation, Natick, Mass) and motorized pullback at 0.5 mm/s. Sixty corresponding coronary artery segments within the coronary artery system were identified in both dual source computed tomography and IVUS using bifurcation points as fiducial markers. In dual source computed tomography data sets, 8 serial parallel cross sections (2-mm slice thickness) were rendered orthogonal to the center line of the coronary artery for each segment. For each cross section, pericoronary adipose tissue within a radius of 3 mm from the coronary artery and enclosed within the epicardium (excluding coronary veins and myocardium) was manually traced and mean CT attenuation values were obtained. Intravascular ultrasound was used to define coronary segments as follows: presence of predominantly fibrous atherosclerotic plaque (hyperechoic), presence of predominantly lipid-rich atherosclerotic plaque (hypoechoic), and absence of atherosclerotic plaque.

Results: In IVUS, 20 coronary segments with fibrous plaque, 20 segments with lipid-rich plaque, and 20 coronary segments without plaque were identified. The mean CT attenuation of pericoronary adipose tissue for segments with any coronary atherosclerotic plaque was −34 ± 14 Hounsfield units (HU), as compared with −56 ± 16 HU for segments without plaque (P = 0.005). The density of pericoronary fat in segments with fibrous versus lipid-rich plaque as defined by IVUS was not significantly different (−35 ± 19 HU vs −36 ± 16 HU, P = 0.8).

Conclusions: Mean CT attenuation of pericoronary adipose tissue is significantly lower for normal versus atherosclerotic coronary segments. This supports a hypothesis of different types of pericoronary adipose tissue, the more metabolically active of which might exert local effects on the coronary vessels, thus contributing to atherogenesis.

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