Israel Medical Association Journal

Background: Acute mesenteric ischemia (AMI) is a medical condition with high levels of morbidity and mortality. However, most patients suspected of AMI will eventually have a different diagnosis. Nevertheless, these patients have a high risk for co-morbidities.

Objectives: To analyze patients with suspected AMI with an alternative final diagnosis, and to evaluate a machine learning algorithm for prognosis prediction in this population.

Methods: In a retrospective search, we retrieved patient charts of those who underwent computed tomography angiography (CTA) for suspected AMI between January 2012 and December 2015. Non-AMI patients were defined as patients with negative CTA and a final clinical diagnosis other than AMI. Correlation of past medical history, laboratory values, and mortality rates were evaluated. We evaluated gradient boosting (XGBoost) model for mortality prediction.

Results: The non-AMI group comprised 325 patients. The two most common groups of diseases included gastrointestinal (33%) and biliary-pancreatic diseases (27%). Mortality rate was 24.6% for the entire cohort. Medical history of chronic kidney disease (CKD) had higher risk for mortality (odds ratio 2.2). Laboratory studies revealed that lactate dehydrogenase (LDH) had the highest diagnostic ability for predicting mortality in the entire cohort (AUC 0.70). The gradient boosting model showed an area under the curve of 0.82 for predicting mortality.

Conclusions: Patients with suspected AMI with an alternative final diagnosis showed a 25% mortality rate. A past medical history of CKD and elevated LDH were associated with increased mortality. Non-linear machine learning algorithms can augment single variable inputs for predicting mortality.

Background: Pulmonary embolism (PE) is the third most frequently occurring cardiovascular disease. However, the clinical presentation in patients with PE is variable.

Objectives: To evaluate the prevalence of radiological findings detected in contrast-enhanced computed tomography angiography (CTA) and their significance in patients with PE; and to assess whether the CTA findings differed in patients receiving tissue plasminogen activator (tPA) therapy from those who did not.

Methods: We retrospectively reviewed CTA scans of 186 patients diagnosed with acute PE. Incidental findings on CTA scan were assessed, including mediastinal and parenchymal lymph nodes, pleural effusion, space-occupying lesions, consolidations, emphysema, and pericardial effusion.

Results: Patients receiving tPA (19.9%) were less likely to have pleural effusion (29.7% vs. 50.3%, P = 0.024). Other CTA findings did not differ between the tPA and non-tPA groups, including lung infiltrates (40.5% vs. 38.9, P = 0.857), space-occupying lesions (5.4% vs. 6.7%, P = 1), pericardial effusion (8.1% vs. 8.7%, P = 1), emphysema (21.6% vs. 17.4%, P = 0.557), lung (18.9% vs. 24.2%, P = 0.498), and mediastinal ( 24.3% vs. 25.5%, P = 0.883) lymph nodes, respectively.

Conclusion: The prevalence of pleural effusion (unilateral or bilateral) was higher in patients not treated with tPA. Therefore, in patients with a borderline condition, the presence of pleural effusion could support the decision not to give tPA treatment.

Background: Trans-catheter valve implantation (TAVI) is a non-surgical alternative for patients with severe aortic stenosis (AS). Pre-procedural computed tomography angiography (CTA) allows accurate “road mapping,” aortic annulus sizing and the detection of incidental findings.

Objectives: To document the prevalence of non-valvular extra-cardiac findings on CTA prior to TAVI and the impact of these findings on the procedure.  

Methods: Ninety AS patients underwent CTA as part of pre-TAVI planning. Scans extended from the clavicles to the groin. Non-vascular non-valvular findings were documented and graded as follows: (A) significant findings causing TAVI cancellation or postponement, (B) significant findings leading to a change in the TAVI procedure approach, (C) non-significant findings not affecting the TAVI procedure. 

Results: TAVI was planned for 90 patients; their average age was 80.2 ± 7.5 years, 53% were females. Overall, non-valvular cardiac, extra-cardiac and extra-vascular significant and non-significant incidental findings were documented in 97% of scans (87/90). Significant pathologies causing TAVI cancellation or postponement (category A) were documented in 8%. Significant findings affecting the TAVI procedure (category B) were found in 16% of patients. 

Conclusions: Pre-TAVI CTA detected non-valvular extra-vascular pathologies leading to procedure cancellation/postponement or procedure modification in 8% and 16%, respectively. Comprehensive CTA evaluation that acknowledges the importance of such findings is of major importance since it might alter the TAVI procedure or even render it inappropriate. 

 

Background: Coronary computed tomography angiography (CCTA) is an established modality for ruling out coronary artery disease. However, it has been suggested that CCTA may be a source of non-negligible radiation exposure.

Objectives: To evaluate the potential degradation in coronary image quality when using prospective gated (PG) CCTA as compared with retrospective gated (RG) CCTA in chest pain evaluation.

Methods: The study cohort comprised 216 patients: 108 consecutive patients in the PG CCTA arm and 108 patients matched for age, gender and heart rate in the RG CCTA arm. Scans were performed using a 64-slice multidetector CT scanner. All 15 coronary segments were evaluated subjectively for image quality using a 5-point visual scale. Dose-length product was recorded for each patient and the effective radiation dose was calculated

Results: The PG CCTA technique demonstrated a significantly higher incidence of step artifacts in the middle and distal right coronary artery, the distal left anterior descending artery, the second diagonal, the distal left circumflex artery, and the second marginal branches. Nevertheless, the diagnostic performance of these scans was not adversely affected. The mean effective radiation doses were 3.8 ± 0.9 mSv vs.17.2 ± 3 mSv for PG CCTA and RG CCTA, respectively (P < 0.0001).

Conclusions: Artifacts caused by the PG CCTA technique (64 MDCT) scanners tended to appear in specific coronary segments but did not impair the overall diagnostic quality of CCTA and there was a marked reduction in radiation exposure. We conclude that 64-slice PG CCTA is suitable for clinical use, especially for acute chest pain "fast track" evaluation targeted at relatively young subjects in a chest pain unit.
 

Background: Coronary CT angiography is an accurate imaging modality; however, its main drawback is the radiation dose. A new technology, the "step and shoot," which reduces the radiation up to one-eighth, is now available.

Objectives: To assess our initial experience using the "step-and-shoot" technology for various vascular pathologies.

Methods: During a 10 month period 125 consecutive asymptomatic patients (111 men and 14 women aged 25–82, average age 54.9 years) with various clinical indications that were appropriate for step-and-shoot CCTA[1] (regular heart rate < 65 beats/minute and body weight < 115 kg) were scanned with a 64-slice multidetector computed tomography Brilliance scanner (Philips, USA). The preparation protocol for the scan was the same as for the regular coronary CTA. All examinations were interpreted by at least one experienced radiologist and one experienced interventional cardiologist. The quality of the examinations was graded from 1 (excellent imaging quality of all coronary segments) to 4 (poor quality, not diagnostic). There were 99 patients without a history of coronary intervention, 13 after coronary stent deployment (19 stents), and 3 after coronary artery bypass graft.

Results: Coronary interpretation was obtained in 122 examinations (97.6%). The imaging quality obtained was as follows: 103 patients scored 1 (82.4%), 15 scored 2 (12%), 4 scored 3 (3.2%) and 3 scored 4 (2.4%). The grades were unrelated to cardiac history or type of previous examinations. Poor image quality occurred because of sudden heart rate acceleration during the scan (one patient), movement and respiration (one patient), and arrhythmia and bad scan timing (in one). Two patients were referred to percutaneous coronary intervention based on the CCTA findings, which correlated perfectly.

Conclusions: Step-and-shoot CCTA is a reliable technique and CCTA algorithm comparable to the regular CCTA. This technique requires the lowest radiation dose, as compared to other coronary imaging modalities, that can be used for all CCTA indications based on the inclusion criteria of low (> 65 bpm) and stable heart rate.

Background: Cardiac computed tomography angiography is a relatively new imaging modality to detect coronary atherosclerosis.

Objectives: To explore the diagnostic value of CTA[1] in assessing coronary artery disease among asymptomatic patients.

Methods: In this retrospective single-centered analysis, 622 consecutive patients underwent CTA of coronary arteries between November 2004 and May 2006 at the Mor Institute for Cardiovascular Imaging in Bnei Brak, Israel. All patients were asymptomatic but had at least one risk factor for atherosclerotic CAD[2]. The initial 244 patients were examined with the 16-slice Brilliance CT scanner (Philips, Cleveland, OH, USA), and in the remaining 378 patients the 64-slice scanner (GE Healthcare, The Netherlands) with dedicated cardiac reconstruction software and electrocardiography triggering was used. Scanning was performed in the cranio-caudal direction. Images reconstructed in different phases of the cardiac cycle using a retrospective ECG-gated reconstruction algorithm were transferred to a dedicated workstation for review by experienced CT radiologists and cardiologists.

Results: Of 622 patients, 52 (8.4%) had severe obstructive atherosclerosis (suspected ≥ 75% stenosis) according to CTA interpretation. Invasive coronary angiography was performed in 48 patients while 4 patients had no further procedure. A non-significant CAD (e.g., diameter stenosis < 70%) was identified in 6 of 48 patients (12%) by selective coronary angiography. Forty-two patients showed severe CAD with at least one lesion of ≥ 70% stenosis. Percutaneous coronary intervention was performed in 35 patients and coronary artery bypass grafting surgery in the other 4 patients. Angioplasty procedures were successful in all 35 patients and stents were utilized in all cases without complications. No further complications occurred among the study cohort undergoing either PCI[3] or surgery. The 6 month survival rate in these patients was 100%.

Conclusions: Non-invasive coronary CTA appears to be a reliable technique, with reasonably high accuracy, to detect obstructive atherosclerosis in asymptomatic high risk patients for atherosclerotic CAD.

Background: Diseases causing increased pulmonary pressure will subsequently cause a dilation of the pulmonary arteries and right heart chambers.

Objectives: To assess the capability of computed tomography angiography and high resolution CT to diagnose and estimate the severity of pulmonary arterial hypertension as compared with standard means of right heart catheterization, echocardiography and pulmonary function tests.

Methods: The study included 38 patients with PHT[1] who underwent CT angiography and HRCT[2] as part of their routine evaluation. Diagnose included: primary PHT (n=20), Eisenmenger syndrome (n=6), scleroderma (n=3), thromboembolic disease (n=3), and others (n=6). Mean pulmonary artery pressure was 58 mmHg (range 39–92 mmHg) by catheterization and peak systolic pressure 79 mmHg (range 40–135) by echocardiography. Findings for the diameters of the main pulmonary artery and its main branches, the ascending aorta, the right atria and ventricle as well as the position of the interventricular septum were compared with 22 chest CT scans as compared to patients with no known clinical history of pulmonary hypertension, performed for other reasons (trauma, oncology follow-up) during the study period. Correlations were also calculated with recent right heart catheterization, echocardiography and pulmonary function tests of the study group.

Results: Mean main pulmonary artery diameter in the study group was 3.55 ± 0.66 cm, pulmonary artery/ascending aorta ratio 1.2 ± 0.29, right pulmonary artery 2.63 ± 0.49 cm, left pulmonary artery 2.57 ± 0.5 cm. All diameters were significantly different from the control group (P < 0.0001). Main and right pulmonary artery diameters correlated to the pressure measurement by echocardiography (P = 0.001). Bronchial collaterals were found in 11 patients (30%). The position of the interventricular septum correlated well with the echocardiography study.

Conclusions: The size of the main pulmonary artery on CT angiography has a good predictive value regarding the severity of PHT.

Objectives: To evaluate the accuracy of 16-slice multi-detector CT angiography in the diagnosis of coronary artery disease, and assess coronary bypass grafts and coronary anomalies.

Methods: We conducted a retrospective study of 223 patients who were examined at our medical center over a period of 2 years with a 16-slice CT angiography scanner and retrospective electrocardiographic gating.

Results: There were no significant complications, and good visualization of the coronary arteries was achieved in all but eight patients. A high correlation with the results of the invasive angiography was noted (sensitivity 85%, specificity 93%, negative predictive value 98%). Altogether, 131 bypass conduits were examined with excellent graft visualization. Several coronary anomalies were detected, as were significant extra-cardiac findings.

Conclusions: Multi-slice CT angiography is a reliable non-invasive diagnostic procedure for demonstration of the coronary arteries and bypass grafts. In the future it will probably replace part of the diagnostic invasive coronary angiography and, as a result, a large proportion of coronary angiography procedures will be therapeutic.