Impact of sublingual nitroglycerin dosage on FFRCT assessment and coronary luminal volume-to-myocardial mass ratio.

OBJECTIVES: Fractional flow reserve computed tomography (FFRCT) depends upon nitroglycerin (NTG) inducing maximal hyperemia. However, the impact of NTG dosages on FFRCT analysis including coronary volume-to-mass ratio (V/M) is unknown. METHODS: Eighty patients with repeat coronary CT angiograms (CCTAs) with different sublingual spray NTG doses (0.4 mg and 0.8 mg) were retrospectively analyzed with 45 patients excluded. Patient and scan demographics, post-stenosis and nadir FFRCT values, coronary volume, and coronary volume-to-mass ratio (V/M) were compared at initial CCTA (0.4 mg NTG) and follow-up CCTA (0.8 mg NTG). Differences were compared by Wilcoxon signed-rank test. RESULTS: Thirty-five patients were included (time between CCTAs, 3.9 ± 1.6 years). Segment involvement score was 2.4 ± 3.3 and 2.8 ± 3.4 at initial and repeat CCTA (0.4 and 0.8 mg NTG), respectively (p = 0.004). There was similar image quality (4.1 ± 0.7 vs 4.1 ± 0.8; p = 0.51). Nadir FFRCT values did not differ in the left (0.4 mg, 0.80 ± 0.08 vs 0.8 mg, 0.80 ± 0.03; p = 0.66), right (0.4 mg, 0.90 ± 0.04 vs 0.8 mg, 0.90 ± 0.06; p = 0.25), or circumflex coronaries (0.4 mg, 0.87 ± 0.06 vs 0.8 mg, 0.88 ± 0.06; p = 0.34). Post-stenosis FFRCT values did not differ (p = 0.65). Coronary volume increased with 0.8 mg of NTG (2639 ± 753 mm3 vs 2844.8 ± 827 mm3; p = 0.009) but V/M ratio did not (p = 0.20). CONCLUSIONS: Use of 0.8 mg versus 0.4 mg of NTG in routine clinical CCTAs significantly increased coronary volume determined from FFRCT analysis but did not alter FFRCT or V/M. Further evaluation of repeat CCTAs in a more contemporaneous fashion using varied nitrate doses and disease severity is needed. KEY POINTS: • Fractional flow reserve from computed tomography (FFRCT) is a noninvasive method for evaluating the coronary arteries and relies on nitroglycerin (NTG) to induce coronary vasodilation, but the impact of different NTG dosages is unknown. • Retrospective analysis evaluated use of different NTG doses on FFRCT. • Increased NTG dose increased coronary luminal volume on FFRCTanalysis, but did not change FFRCTvalues.

The imaging features of nontuberculous mycobacterial immune reconstitution syndrome.

OBJECTIVE: The purpose was to characterize the spectrum of imaging findings of nontuberculous mycobacterial immune reconstitution syndrome in patients infected with the human immunodeficiency virus. METHODS: A retrospective review of 33 human immunodeficiency virus-infected patients with nontuberculous mycobacterial immune reconstitution syndrome was performed. Radiography, ultrasound, and computed tomography (CT) imaging was reviewed. RESULTS: Intrathoracic and intra-abdominal abnormalities were identified in 16 and 14 patients, respectively. Lymphadenopathy was detected on chest radiographs in 11 patients and on CT in 13. Focal consolidation (n = 8) and centrilobular nodularity (n = 8) were common CT findings. Lymphadenopathy was the predominant abdominal finding (n = 10). Splenomegaly (n = 9), ascites (n = 7), and multiple hypoattenuating splenic lesions (n = 6) were additional findings. Peripheral lymph node masses were detected in 7 patients. CONCLUSIONS: The most common manifestation of nontuberculous mycobacterial immune reconstitution syndrome is lymphadenopathy. Other common findings are pulmonary consolidation and centrilobular nodularity, ascites, splenomegaly, multiple hypoattenuating splenic lesions, and peripheral lymphadenopathy.