No abstract

To evaluate the effective radiation dose and image quality resulting from use of 100 vs. 120 kV among patients referred for cardiac dual source CT exam (DSCT). Prospective data was collected on 294 consecutive patients referred for DSCT. For each scan, a physician specializing in cardiac CT chose all parameters including tube current and voltage, axial versus helical acquisition, and use of tube current modulation. Lower tube voltage was selected for thinner patients or when lower radiation was desired for younger patients, particularly females. For each study, image quality (IQ) was rated on a subjective IQ score and contrast (CNR) and signal-to-noise (SNR) ratios were calculated. Tube voltage of 100 kV was used for 77 (26%) exams while 120 kV was used for 217 (74%) exams. Use of 100 kV was more common in thinner patients (weight 166 lbs vs. 199 lbs, P < .001). The effective radiation dose for the 100 and 120 kV scans was 8.5 and 15.4 mSv respectively. Among scans utilizing 100 and 120 kV, there was no difference in exam indication, use of beta blockers, heart rate, scan length and use of radiation saving techniques such as prospective ECG triggering and tube current modulation. The IQ score was significantly higher for 100 kV scans. While 100 kV scans were found to have higher image noise then those utilizing 120 kV, the contrast-to-noise and signal-to-noise were significantly higher (SNR: 9.4 vs. 8.3, P = .02; CNR: 6.9 vs. 6.0, P = .02). In selected non-obese patients, use of low kV results in a substantial reduction of radiation dose and may result in improved image quality. These results suggest that low kV should be used more frequently in non-obese patients.

No abstract

A 16-year-old girl from an area in Brazil where tuberculosis was endemic was admitted because of recurrent chest pain, progressive dyspnea with exertion, and inability to climb more than 1 flight of stairs. She described fatigue, weight loss, night sweats, and adenopathy of her right axilla and neck during the previous 3 months. On admission she looked distressed, with a heart rate of 76 bpm and blood pressure of 110/55 mm Hg. The ECG demonstrated sinus rhythm with first-degree heart block ( Figure 1).Her admission chest radiograph demonstrated cardiomegaly with pulmonary edema (Figure 2). Her cardiac enzymes were negative. The patient underwent cardiac evaluation with 2-dimensional echocardiography (not shown), which revealed an interatrial septal mass, mild tricuspid regurgitation, preserved systolic function, and moderate pericardial effusion.For further characterization of the mass, cardiovascular magnetic resonance imaging (MRI) was performed. Coronal black-blood T2-Turbo Spin Echo and T2-Short T1/Tau Inversion Recovery images of the chest showed adenopathy of the right axilla and a multicystic mass located on the posterior mediastinum (Figure 3). Four-chamber view cine-MRI demonstrated mitral and tricuspid regurgitation, pericardial effusion, and an interatrial septum mass (Figure 4A and 4B). A large retrocardiac pulsatile lesion involving the distal thoracic aorta was also noted (Figure 4 and Movie I of the online-only Data Supplement). Delayed-enhancement MRI confirmed the rounded interatrial septal mass with no evidence of enhancement, consistent with a hematoma of the interatrial septum ( Figure 4C), possibly secondary to a leaking aortic root pseudoaneurysm ( Figure 5B and Movie II of the online-only Data Supplement).Time-resolved contrast-enhanced 3-dimensional magnetic resonance angiography demonstrated multiple pseudoaneurysms extensively distributed throughout the ascending and descending thoracic aorta. Longitudinal aorta and 4-chamber views further depicted partially thrombosed pseudoaneurysms, extensive thickening, and late enhancement of the thoracic aortic wall ( Figures 4C and 5), indicating a likely inflammatory cause.Excisional biopsy of her palpable cervical node was performed after her purified protein derivative test proved to be highly reactive (18 mm). The biopsy results demonstrated caseous and noncaseous necrotizing granulomas with positive culture for acid-fast bacilli ( Figure 6).The patient was given an antitubercular 4-medication regimen. Planned surgical intervention decision was precluded when the patient experienced sudden hypovolemic