Comprehensive low-dose imaging of carotid and coronary arteries with a single-injection dual-source CT angiography protocol.

AIM: To assess the feasibility of a fast single-bolus combined carotid and coronary computed tomography angiography (CTA) protocol in asymptomatic patients. MATERIALS AND METHODS: Thirty-three consecutive patients (18 women and 15 men) with a median age of 61 ± 14 years old (range 37-87 years) with known or suspected atherosclerotic disease were enrolled in this prospective study. A single breath-hold, single biphasic injection protocol (50 ml at 3 ml/s, 50 ml at 5 ml/s, 50 ml saline flush at 5 ml/s) was used for combined CTA imaging of the supra-aortic (SAA) and coronary arteries (CA) on a 64-slice dual-source CT (DSCT) machine. Helical CTA acquisition of the SAA was followed by prospective electrocardiography (ECG)-triggered coronary CTA. Subjective (four-point scale) image quality and objective signal-to-noise (SNR) and contrast-to-noise (CNR) measurements were performed. Vascular disease was graded on a four-point scale (grade 1: absent; grade 2: mild, grade 3: moderate; grade 4: severe). The radiation dose was recorded for each patient. RESULTS: The average enhancement and subjective quality score of SAA and CA segments were 396 HU/358 HU and 1.2 ± 0.3/1.72 ± 0.4, respectively. The SNR was 27.1 ± 1.7 in the SAA and 21.6 ± 1.6 in the CA (p < 0.0001). The CNR was 18.1 ± 1.2 and 15.9 ± 1.8, respectively (p = 0.4). Four percent of SAA and 14% of CA segments (mostly due to peri-venous streak artefacts and small calibre, respectively) produced non-diagnostic images. SAA findings were as follows: 26/33 (79%) patients showed no disease and 6/33 (18%) had grade 2 and 1/33 (3%) had grade 3 disease. CA findings were as follows: 25/33 (76%) showed no disease and 6/33 (18%) patients had grade 2 and 2/33 (6%) had grade 3 disease. Five patients had disease in both districts. The average radiation dose for the combined CTA angiogram was 4.3 ± 0.6 mSv. CONCLUSION: A fast, low-dose combined DSCT angiography protocol appears technically feasible for imaging carotid and coronary atherosclerotic disease.

Does sialography require antibiotic prophylaxis?

The objective of this study was to identify if bacteraemias occur during sialography, which could predispose to endocarditis in susceptible patients. Patients requiring sialography who gave informed consent were included in the trial. Patients taking antibiotics, or who were predisposed to infective endocarditis, were excluded. Sialography was performed using a standard hand injection technique with a water-soluble non-ionic contrast agent (Niopam, Bracco, UK). An indwelling cannula was inserted into the forearm prior to the procedure and then three blood samples of at least 10 ml were taken: sample one before sialography; sample two was taken as a continuous withdrawal during the sialographic procedure; and sample three over a further 10 min period after sialography. The blood samples were cultured for bacteria using the BacT/ALERT system (BioMerieux, UK). 32 patients were included in the study. No samples showed evidence of bacteraemia. Three patients had bacterial contamination from skin commensals. Using the rule of three, we have shown a 95% confidence interval of 3/32 = 0.09. In conclusion, the results of this study suggest that sialography is not associated with bacteraemia.

3D high-spatial-resolution cerebral MR venography at 3T: a contrast-dose-reduction study.

BACKGROUND AND PURPOSE: The effect of various contrast-dose regimens for cerebral MR venography (MRV) has not been previously evaluated at 3T, to our knowledge. Our purpose was to evaluate and compare the diagnostic image quality resulting from half-versus-full-dose contrast regimens for high-spatial-resolution 3D cerebral MRV at 3T. MATERIALS AND METHODS: Forty consecutive patients with known or suggested cerebrovascular disease underwent 3D high-spatial-resolution (0.7 x 0.6 x 0.9 mm(3)) cerebral contrast-enhanced MRV (CE-MRV) at 3T, by using an identical acquisition protocol. Patients were assigned to 1 of 2 groups: 1) full-dose (approximately 0.1 mmol/kg), and 2) half-dose (approximately 0.05 mmol/kg). Two readers evaluated the resulting images for overall image quality, venous structure definition, and arterial contamination. Signal intensity-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were evaluated in 8 consistent sites. Statistical analysis was performed by using Mann-Whitney U, Wilcoxon signed rank, and t tests and a kappa coefficient. RESULTS: Both readers scored venous-structure definition as excellent or sufficient for diagnosis in approximately 90% of segments for the full-dose group (kappa = 0.87) and in approximately 80% of segments for the half-dose group (kappa = 0.85). Delineation grades were significantly lower for small venous segments, including the middle cerebral, septal, superior cerebellar, inferior vermian, posterior tonsillar, and thalamostriate veins in the half-dose group (P < .01). No significant difference existed for arterial contamination grades between the 2 groups (P > .05). SNR and CNR values were lower in the half-dose group (P < .01). CONCLUSIONS: At 3T, high-spatial-resolution cerebral MRV can be performed with contrast doses as low as 7.5 mL, without compromising image quality as compared with full-dose protocols, except in the smallest veins, and without compromise of acquisition speed or spatial resolution.

Coronary artery to pulmonary artery fistulae with multiple aneurysms: radiological features on dual-source 64-slice CT angiography.

Coronary artery fistula is a rare vascular anomaly in which there is abnormal communication between the coronary artery and the great vessels or cardiac chambers. We report the case of a 66-year-old man with two separate coronary artery to pulmonary artery fistulas (one of which demonstrated multiple aneurysms), which were diagnosed on dual-source 64-slice coronary CT and reconfirmed by coronary catheter angiography.

Left ventricular ejection fraction using 64-slice CT coronary angiography and new evaluation software: initial experience.

The purpose of this study was to evaluate the feasibility and reliability of software-based quantification of left ventricular function using 64-slice CT coronary angiography. Data were collected from 26 subjects who underwent a 64-slice coronary CT angiography study. Two volumetric data sets at end diastole and end systole were reconstructed from each scan by means of retrospective electrocardiogram gating. Data sets were evaluated with a prototype of now commercially available software (Syngo Circulation I; Siemens Medical Solutions, Erlangen, Germany), which automatically segments the blood volume in the left ventricle after the user defines the mitral valve plane and any point within the ventricle. After segmentation of the blood pool in end systole and end diastole, the software automatically measures end systolic and end diastolic volume and calculates stroke volume and ejection fraction (EF). Two readers processed all CT data sets twice to assess for intra- and inter-observer variation. In addition, CT EF measurements were compared with those obtained by clinical echocardiography. Intra-observer variation for the calculated EF with CT were 13.6% and 15.6% for Readers 1 and 2, respectively. No significant difference in left ventricular functional parameters on CT existed between the readers (p > 0.05). A Bland-Altman plot revealed a slight mean difference between EF measurements on CT and echocardiography, with all differences falling within two standard deviations of the mean in the setting of wide limits of agreement. In conclusion, assessment of left ventricular EF from CT coronary data using the new analysis software is rapid and easy. The software is user-friendly and provides good reproducibility for EF measurements with CT.

Low-dose, time-resolved, contrast-enhanced 3D MR angiography in cardiac and vascular diseases: correlation to high spatial resolution 3D contrast-enhanced MRA.

AIM: To evaluate the effectiveness of low-dose, contrast-enhanced, time-resolved, three-dimensional (3D) magnetic resonance (MR) angiography (TR-MRA) in the assessment of various cardiac and vascular diseases, and to compare the results with high-resolution contrast-enhanced MRA (CE-MRA). MATERIALS AND METHODS: Thirty consecutive patients underwent contrast-enhanced 3D TR-MRA and high spatial resolution 3D CE-MRA for evaluation of cardiac and thoracic vascular diseases at 1.5 T, and neurovascular, abdominal and peripheral vascular diseases at 3T. Gadolinium-based contrast medium was administered at a constant dose of 5 ml for TR-MRA, and 20 ml (lower extremity 30 ml) for CE-MRA. Two readers evaluated image quality using a four-point scale (from 0=excellent to 3=non-diagnostic), artefacts and findings on both datasets. Interobserver variability was tested with kappa coefficient. RESULTS: The overall image quality for TR-MRA was in the diagnostic range (median 0, range 0-1; k=0.74). Readers demonstrated important additional dynamic information on TR-MRA in 28 of 30 patients (k=0.84). Confident evaluation of organ perfusion (n=23), arteriovenous malformation/fistula flow patterns (n=7), exclusion of intra-cardiac shunts (n=6), and assessment of stent and conduit patency (n=5) were performed by both readers using TR-MRA. Readers demonstrated fine vascular details with higher confidence in 10 patients on CE-MRA. Using CE-MRA, Reader 1 and 2 depicted anatomical details in 6 and 5 patients, respectively, only on CE-MRA. CONCLUSION: Low-dose TR-MRA yields rapid and important functional and anatomical information in patients with cardiac and vascular diseases. Due to limited spatial resolution, TR-MRA is inferior to CE-MRA in demonstrating fine vascular details.