The effects of sublingual nitroglycerin administration in coronary computed tomography angiography.

PURPOSE: The purpose of our study was to compare coronary luminal diameters in patients undergoing coronary computed tomography angiography (CCTA) performed with different sublingual nitroglycerin (NTG) spray regimens. MATERIALS AND METHODS: We retrospectively reviewed CCTA studies performed in two historical groups (Group 1, single dose nitroglycerin 2 min prior to CCTA, and Group 2, single dose 10 min prior), and a current protocol group (Group 3, single dose at 2 and 10 min prior). Thirty patients were evaluated per group. Two blinded readers measured coronary luminal diameters with comparison of diameter measurements. A third blinded reader assessed image quality of coronary artery segments. RESULTS: Significant group-level differences in median luminal diameters were identified. Higher median diameters (95% CI) across all segments of 0.40 mm (0.20, 0.60) for Group 2 versus 1 and 0.50 mm (0.30, 0.70) for Group 3 versus 1 were recorded (both P < 0.001). No significant differences in median luminal diameters were found between Groups 2 and 3. No significant differences in image quality were found among the groups apart from higher image quality for the distal LAD for both Groups 2 and 3 compared to Group 1. CONCLUSION: Sublingual nitroglycerin spray administered as a single dose at 10 minute dilates coronary arteries more than when only administered at 2 min prior to CCTA. Combined two doses at 10 and 2 min prior to CCTA do not yield further dilatation of coronary arteries.

Retrospective review of CT brain image quality, diagnostic adequacy and radiation dose in a paediatric population imaged at a non-paediatric tertiary hospital.

INTRODUCTION: Minimising radiation exposure in paediatric imaging examinations whilst maintaining acceptable diagnostic quality continues to present a challenge. The aims of this study were to assess institutional compliance of paediatric CT brain (CTB) examinations performed in an adult hospital with ARPANSA radiation dose recommendations and to compare qualitative CTB diagnostic acceptability with objective imaging parameters and radiation dose. METHODS: A retrospective review of 115 consecutive paediatric CTB examinations was undertaken at an adult tertiary referral centre in Australia over a 2-year period. Dose length product (DLP) was compared with the ARPANSA standards. CTB image quality was subjectively classified by two neuroradiologists independently, with discordant results resolved by consensus. Objective assessment of image quality included measurements of signal-to-noise (SNR) and contrast-to-noise ratios (CNR) of grey and white matter. RESULTS: All patient scans complied with ARPANSA DLP recommendations; however, 10 out of 115 scans were classified as being of diagnostically suboptimal image quality. These scans had significantly lower mean DLP values compared with diagnostically adequate examinations (105.1 vs 379.2 mGy.cm; P < 0.0001). CTB scans of adequate diagnostic quality, when compared to suboptimal scans, had significantly higher CNR (1.8 vs 1.1; P < 0.0001) and SNR in grey (7.1 vs 4.6; P < 0.0001) and white matter (5.6 vs 3.8; P < 0.0001). CONCLUSION: All CTB examinations in this series complied with the ARPANSA DLP recommendations; however, 9% were of suboptimal diagnostic image quality. While it is important to minimize unnecessary radiation exposure, our results suggest that excessively low DLP values can lead to suboptimal diagnostic image quality.

Highly Accelerated Breath-Hold Noncontrast Electrocardiographically- and Pulse-Gated Balanced Steady-State Free Precession Magnetic Resonance Angiography of the Thoracic Aorta: Comparison With Electrocardiographically-Gated Computed Tomographic Angiography.

OBJECTIVE: The aim of this study was to evaluate agreement of measured thoracic aortic caliber in patients with aortic disease, using electrocardiographically-(ECG) and pulse-gated breath-hold noncontrast balanced steady-state free precession MRA (ECG-MRA, P-MRA) at 1.5 T, compared with ECG-gated computed tomographic angiography (CTA). METHODS: Thirty-one patients underwent ECG-MRA, P-MRA, and CTA. Two readers independently measured aortic caliber in 7 segments, with agreement between techniques and readers evaluated. Image quality was qualitatively assessed. RESULTS: There was overall excellent agreement among ECG-MRA, P-MRA, and CTA for measured aortic caliber (Lin's concordance correlation coefficient ≥0.94, all comparisons); however, lower concordance was noted at the annulus (Lin's concordance correlation coefficient <0.6) at segmental assessment. There was excellent interreader agreement for aortic caliber for all 3 techniques (intraclass correlation coefficient >0.94). Image quality was poorer for both MRA techniques compared with CTA, particularly at the aortic root. CONCLUSIONS: Electrocardiographically-gated MRA and P-MRA at 1.5 T achieve comparable thoracic aortic measurements to gated CTA in clinical patients, despite inferior image quality.