Dual-phase 16 slice CT angiography in stroke imaging: a poor man's multiphase study?

Multiphase CT angiography (CTA) in collateral assessment provides time-resolved cerebral angiograms of the intracranial vasculature, requiring a high-speed multidetector CT (MDCT) scanner with ≥ 64 slices. Unfortunately, many hospitals are equipped with lower speed MDCT scanners. Herein, we present our experience performing dual-phase CTA (d-CTA) on a 16 slice MDCT with a biphasic rate injection to grade intracranial collaterals as predictor of clinical outcome. 42 patients were evaluated with both dual-phase CTA (d-CTA) and single-phase CTA (s-CTA) for occluded anterior intracranial circulation and collaterals. They were treated with endovascular reperfusion. Univariate and multivariate analyses were performed to define the independent predictors for favorable outcome at 3 months. Good collateral circulation status on d-CTA was associated with a lower median 24-h (5 vs. 7.5, p = 0.03) and discharge (2 vs. 4.6, p = 0.04) NIHSS. A logistic regression model showed that only age (OR 0.95, 95% CI 0.91-0.98, p = 0.03) and good collateral circulation status at d-CTA (OR 4.3, 95% CI 1.87-11.3, p < 0.01) were independent predictors of favorable functional outcome at 3 months, but that s-CTA was not. The collateral status on d-CTA can be a useful predictor for clinical outcome in acute stroke patients. The proposed protocol adapted to a low-speed MDCT scanner could be of particular interest in hospitals without access to the more up-to-date technology.

MR angiography of the carotid arteries: parameters affecting image quality.

RATIONALE AND OBJECTIVES: This study was performed to evaluate the relationship between dose levels of contrast medium and image quality in magnetic resonance (MR) angiography of the carotid arteries with fluoroscopically monitored, manually triggered, elliptically ordered image acquisitions. MATERIALS AND METHODS: Twenty-five patients with clinical indications for angiography of the carotid arteries were examined with MR at 1.5 T by using a fluoroscopically monitored, manually triggered, elliptically ordered pulse sequence with the administration of one of three different volumes of gadolinium-based contrast medium. The signal intensities of the vessel lumen and the surrounding tissues were measured in single partitions at the origin of the common carotid artery, the carotid bifurcation, and the intracranial internal carotid arteries. The contrast-to-noise ratio in these regions of interest also was measured. Maximum intensity projection image quality was appraised for blurring, artifacts, venous enhancement, background suppression, and contrast medium distribution. RESULTS: No artifacts or venous enhancement was observed. The position of the fluoroscopic section affected the distribution of contrast medium along the vessel, as evidenced by the difference between the contrast-to-noise ratio at the origin of the common carotid artery and the ratio at the carotid bifurcation and the intracranial internal carotid arteries (P < .01). The contrast medium dose administered was strongly correlated with image quality (r = 0.90). CONCLUSION: Contrast medium dose is related to image quality in MR angiography of the carotid arteries performed with elliptical ordering, fluoroscopic monitoring, and manual triggering.

Inversion time prolongation at late enhancement cardiac MRI in a myeloma patient.

A patient undergoing chemotherapy for multiple myeloma had a sudden onset of heart failure. Cardiac magnetic resonance was performed after echocardiography to rule out myocardial late enhancement, which was not detected. In- terestingly, the inversion time of the T1-weighted inversion recovery late enhancement sequence needed to be significantly increased (from the usual 250-300 to 490 ms) to obtain diagnostic images. This report presents the clinical case of this patient, and discusses potential implications.

Magnetic resonance angiography with elliptical ordering and fluoroscopic triggering of the renal arteries.

PURPOSE: To evaluate centric ordered MR angiography with fluoroscopic triggering of renal artery disease. MATERIAL AND METHODS: 21 patients underwent MR-Angiography with a fluoroscopically triggered centric ordered sequence. The fluoroscopic trigger was obtained with the parameters that follow: TR/TE/TI: 1000/1.7/500 ms; NEX 1; MTX 141 x 256; SL 10mm; AT 0.83 s. The angiographic sequence was obtained with a CareBolus sequence (TR/TE: 3.9/1.5 ms; NEX 1; MTX 176 x 512; SL 1.1 mm; AT ~20s) after the intra-venous injection of 18 ml of Gd-BOPTA 0.5M followed by saline solution at a rate of 2.5 ml.s-1. Contrast-to-noise ratio (CNR) was obtained at the origin of the renal arteries. Statistical analysis was performed considering image quality, contrast media dose and the CNR. RESULTS: Ringing artifacts never occurred. The collaboration of the patient and the use of the earphones are critical to avoid motion artifacts. Renal veins have never been visualized. High CNR were noticed. CONCLUSIONS: This technique allows a more efficient use of the contrast media. MRA with centric ordering and fluoroscopic triggering allows an optimal and easy assessment of the renal arteries.