Diagnostic accuracy of cardiac computed tomography angiography for myocardial infarction

AIM:To investigate diagnostic accuracy of high,low and mixed voltage dual energy computed tomography(DECT) for detection of prior myocardial infarction(MI).METHODS:Twenty-four consecutive patients(88% male,mean age 65 ± 11 years old) with clinically documented prior MI(】 6 mo) were prospectively recruited to undergo late phase DECT for characterization of their MI.Computed tomography(CT) examinations were performed using a dual source CT system(64-slice Definition or 128-slice Definition FLASH,Siemens Healthcare) with initial first pass and 10 min late phase image acquisitions.Using the 17-segment model,regional systolic function was analyzed using first pass CT as normal or abnormal(hypokinetic,akinetic,dyskinetic).Regions with abnormal systolic function were identified as infarct segments.Late phase DE scans were reconstructed into:140 kVp,100 kVp,mixed(120 kVp) images and iodine-only datasets.Using the same 17-segment model,each dataset was evaluated for possible(grade 2) or definite(grade 3) late phase myocardial enhancement abnormalities.Logistic regression for correlated data was used to compare reconstructions in terms of the accuracy for detecting infarct segments using late myocardial hyperenhancement scores.RESULTS:All patients reported prior history of documented myocardial infarction,with most occurring more than 5 years prior(n = 18;75% of cohort).Fiftyfive of 408(13%) segments demonstrated abnormal wall motion and were classified as infarct.The remaining 353 segments were classified as non-infarcted segments.A total of 1692 segments were analyzed for late phase enhancement abnormalities,with 91(5.5%) segments not interpretable due to artifact.Combined grades 2 and 3 compared to grade 3 only enhancement abnormalities demonstrated significantly higher sensitivity and similar specificity for detection of infarct segments for all reconstructions evaluated.Evaluation of different voltage acquisitions demonstrated the highest diagnostic performance for the 100 kVp reconstruction which had higher diagnostic accuracy(87%;95%CI:80%-90%),sensitivity(86%-93%;95%CI:54%-78%) and specificity(90%;95%CI:86%-93%) compared to the other reconstructions.For sensitivity,there were significant differences noted between 100 kVp vs 140 kVp(P【0.0005),100 kVp vs mixed(P【0.0001),and 100 kVp vs iodine only(P【0.005) using combined grade 2 and grade 3 perfusion abnormalities.For specificity,there were significant differences noted between 100 kVp vs 140 kVp(P【0.005),and 100 kVp vs mixed(P【0.01) using combined grades 2 and 3 perfusion abnormalities.CONCLUSION:Low voltage acquisition CT,100 kVp in this study,demonstrates superior diagnostic performance when compared to higher and mixed voltage acquisitions for detection of prior MI.

Dual source computed tomography coronary angiography in new onset cardiomyopathy

AIM: To evaluate safety and utility of coronary computed tomography angiography (CCTA) compared to invasive coronary angiography (ICA) in new cardiomyopathy. METHODS: Eighteen patients (mean age 56.5 years, 10 males) who presented for evaluation of new onset heart failure with evidence of systolic dysfunction (ejection fraction < 40%) on echocardiography and recent ICA were prospectively enrolled. Patients with known coronary artery disease, atrial fibrillation, creatinine > 1.5 g/dL, and contraindication to intravenous contrast administration were excluded. CCTA was performed using a dual source 64-slice scanner. Mean heart rate was 75 beats per minute. Stenosis was graded for each coronary segment as: none, mild (< 50%), moderate (50%-70%), severe (> 70%), or non-evaluable. Ischemic cardiomyopathy (ICM) was diagnosed if severe stenosis was present in the left main, proximal left anterior descending artery, or two or more major arteries. RESULTS: Two patients were diagnosed with ICM by ICA. CCTA correctly identified 2 patients with ICM and 16 patients as non-ICM. CCTA successfully evaluated 240/246 coronary segments with an accuracy of 97.5%, sensitivity 70%, specificity 98.7%, positive predictive value of 70%, and negative predictive value of 98.7% for identifying severe stenosis on a per-segment level. CONCLUSION: Dual source 64-slice multi-detector CCTA is a safe, accurate, and non-invasive technique for diagnosing ICM in patients presenting during the acute phase of newly diagnosed cardiomyopathy.