Multidetector computed tomography coronary angiography: sublingual nitroglycerine improves image quality significantly because of peripheral coronary vasodilatation.

PURPOSE: In this study, we investigated the influence of sublingual nitroglycerine (NTG) on the peripheral diameter, intraluminal contrast agent density, and image quality of coronary arteries during computed tomography coronary angiography (CTCA). MATERIALS AND METHODS: Thirty patients with sublingual NTG application were matched to 30 patients without NTG. The diameters of the left anterior descending coronary artery (LAD), the left circumflex coronary artery and the right coronary artery were measured at 1-, 4-, and 8-cm length of each vessel as well as the intraluminal contrast agent density along the LAD. Vessel diameters and contrast attenuation at 4 and 8 cm were referenced against the values at 1 cm and processed as percentage reduction. Image quality of the posterior descending artery was assessed subjectively by 2 independent observers. RESULTS: The percentage of peripheral vessel diameter reduction and the peripheral attenuation of contrast agent density for all measured coronary arteries was significantly smaller in the group with NTG administration. The image quality of the posterior descending artery was significantly higher in the group with NTG. CONCLUSIONS: Sublingual administration of NTG before CTCA results in improved diagnostic image quality because of a significant dilatation and improved intraluminal contrast agent density of the peripheral vessels.

Aortic wall thickness assessed by multidetector computed tomography as a predictor of coronary atherosclerosis.

Purpose of this study was the evaluation of the thoracic aortic wall thickness as a potential identifier of patients at increased risk for future cardiac events. Thoracic aortic wall thickness was measured with MDCT in 160 patients. The CT-scans were implemented as non-invasive coronary angiography studies. Relationships between aortic wall thickness, sex, age, major risk factors and atherosclerotic plaque burden of the coronary arteries were explored. Higher values of maximum aortic wall thickness of the descending aorta (women P = 0.02, men P = 0.01) were found in patients with coronary atherosclerosis, compared to patients with same gender but excluded atherosclerosis. Aortic wall thickness of the mid-portion of the descending aorta of 3.0 mm is associated with coronary artery disease (CAD) with a specificity of 96.6% (sensitivity 27.5%) and a positive predictive value (PPV) of 93.3%. For patients with two or more major risk factors and a maximum wall thickness of equal or more than 2.6 mm we found a PPV of 100%. We conclude that measurements of maximum wall thickness of the descending aorta are a potential tool for detecting patients with coronary atherosclerosis. The potential effect of combining measurements of aortic wall thickness at routine chest CT studies with a possible cardiovascular screening is substantial and merits further study.

Prospectively gated axial CT coronary angiography: preliminary experiences with a novel low-dose technique.

To assess image quality and radiation exposure with prospectively gated axial CT coronary angiography (PGA) compared to retrospectively gated helical techniques (RGH). Forty patients with suspected coronary artery disease (CAD) and a stable heart rate below 65 bpm underwent CT coronary angiography (CTCA) using a 64-channel CT system. The patient cohort consisted of 20 consecutive patients examined using a PGA technique and 20 patients examined using a standard RGH technique. Both groups were matched demographically according to age, gender, body mass index, and heart rate. For both groups, two independent observers assessed image quality for all coronary segments on an ordinal scale from 1 (nonassessable) to 5 (excellent quality). Image quality and radiation exposure were compared between patient groups. There were no significant differences in vessel-based image quality between the two groups (P > 0.05). Mean (+/- SD) effective radiation exposure in the PGA group was 3.7 +/- 0.8 mSv compared to 18.9 +/- 3.8 mSv in the RGH group without ECG-based tube current modulation (P < 0.001). Preliminary experience shows PGA technique to be a promising approach for CTCA resulting in a substantial reduction in radiation exposure with image quality comparable to that of standard RGH technique.

Multienergy photon-counting K-edge imaging: potential for improved luminal depiction in vascular imaging.

The purpose of this study was to investigate whether spectral computed tomography (CT) has the potential to improve luminal depiction by differentiating among intravascular gadolinium-based contrast agent, calcified plaque, and stent material by using the characteristic k edge of gadolinium. A preclinical spectral CT scanner with a photon-counting detector and six energy threshold levels was used to scan a phantom vessel. A partially occluded stent was simulated by using a calcified plaque isoattenuated to a surrounding gadolinium chelate solution. The reconstructed images showed an effective isolation of the gadolinium with subsequent clear depiction of the perfused vessel lumen. The calcified plaque and the stent material are suppressed.

Objective evaluation of vessel attenuation in multidetector-row computed tomographic pulmonary angiography using high-density contrast material for the detection of pulmonary embolism.

OBJECTIVE: The purpose of this study was to analyze the pulmonary vessel enhancement obtainable using high-density contrast material and saline flushing with automated bolus tracking for multidetector-row computed tomographic (MDCT) pulmonary angiography in a routine clinical setting. METHODS: Attenuation values of pulmonary vessels were retrospectively measured in 51 CT scans performed on a 40-channel MDCT for unselected emergency patients with clinically suspected pulmonary embolism. RESULTS: Mean vascular attenuation measured 326.7 +/- 104 Hounsfield units (HU) in the pulmonary trunk and 299.1 +/- 102 HU in the left distal lower lobe artery. Mean vascular attenuation values in the distal lower lobe artery were equal or higher than 150 HU for 94.1% (48/51) of patients. CONCLUSIONS: In conclusion, the combination of high-density contrast media and saline flushing with automated bolus tracking on a fast CT scanner reliably results in a homogenously high attenuation of pulmonary vessels, allowing precise delineation of clots down to the subsegmental level in MDCT pulmonary angiography.

A 25-year-old woman with a gastric GIST and a PET-positive epicardial tumor.

BACKGROUND: A 25-year-old woman presented with a history of abdominal pain. Endoscopy of the upper gastrointestinal tract revealed a tumor that protruded into the prepyloric antrum. After resection, a 'high-risk' gastrointestinal stromal tumor was histologically confirmed. INVESTIGATIONS: Endoscopy, endoscopic ultrasound, hemigastrectomy, [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT scan, histological examination, immunohistochemistry, cardiac MRI, high-resolution CT with electrocardiogram gating, CT angiography, and cardiac surgery. DIAGNOSIS: Gastrointestinal stromal tumor, epicardial paraganglioma, and Carney's syndrome. MANAGEMENT: Abdominal ultrasound and endoscopy combined with endoscopic ultrasound, annual FDG-PET/CT scan.

Multislice MR first-pass myocardial perfusion imaging: impact of the receiver coil array.

PURPOSE: To compare a new 12-element body phased-array coil with a conventional four-element surface receiver coil array to provide increased signal-to-noise ratios (SNRs) for cardiac steady state free precession (SSFP) perfusion imaging. MATERIALS AND METHODS: Thirteen consecutive patients were included in the study. Patients were examined both with a four-element surface coil array and a 12-element body coil array. First-pass myocardial perfusion imaging using saturation recovery SSFP was acquired during antecubital injection of Gd-DTPA. Imaging parameters: TR 2.8 msec/TE 1.3 msec, flip angle 50 degrees , bandwidth 960 Hz/pixel and half-Fourier acquisition. SNR was calculated using six regions of interest (ROI) for the myocardial perfusion scans. Calculations of corresponding ROIs using the two different coil setups were compared using analysis of variance (ANOVA). Semiquantitative perfusion parameters were calculated for both groups. RESULTS: The mean SNR in myocardial perfusion imaging increased by 21% using the 12-element coil setup (P < 0.001) when compared to the four-element coil. ROI comparisons revealed an increased signal inhomogeneity with the 12-element coil when compared to four-element coil experiments. Absolute normal range values of semiquantitative perfusion parameters were consistently higher using the 12-element coil setup (P < 0.001). CONCLUSION: The 12-element coil array provides higher SNR, but these improvements come with trade-offs in image homogeneity. Increased SNR translates into higher semiquantitative perfusion values and offers the potential for improved detection of perfusion defects.