Comparison of calcium scoring with 4-multidetector computed tomography (4-MDCT) and 64-MDCT: a phantom study

COMPARISON OF RADIATION DOSE AND IMAGE QUALITY IN HEAD CT SCANS AMONG MULTIDETECTOR CT SCANNERS

The present study compares three different multidetector CT (MDCT) scanners for routine brain imaging in terms of image quality and radiation doses. The volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (E) were calculated. Subjective image assessment was obtained based on a scale ranging from 1 (unacceptable) to 5 (optimum). All images scored 3.5 or over, with the 160-slice MDCT images being favoured. For the 4-, 16- and 160-slice MDCT scanners, the respective median values for CTDIvol were 57 mGy, 41 mGy, and 28 mGy; DLP values were 901 mGy.cm, 680 mGy.cm, and 551 mGy.cm; and effective doses were 2 mSv, 1.5 mSv, and 1 mSv, respectively. Compared to the 160-slice MDCT, the dose values for the 4- and 16-slice units were significantly greater. In practice, the CT modality used must be carefully selected to avoid elevated radiation doses and maintain image quality.

Coronary age, based on coronary calcium measurement, is increased in patients with morbid obesity

Purpose

Obesity is a well-known of risk factor for atherosclerosis. However, recently an “obesity paradox” has been discussed, which is considered as a protective effect of obesity on the development coronary artery disease (CAD). An aim of the study was to investigate the risk of CAD in morbidly obese patients using coronary artery calcium measurement.

Material and methods

Fifty-one patients with morbid obesity (BMI ≥ 40 kg/m²) and thirty controls were scanned to determine the amount of coronary artery calcification (CAC), which was expressed as calcium score (CS) and coronary age (CA). The control group consisted of patients scanned for the clinical suspicion of CAD, who did not fulfil the criteria of obesity.

Results

Mean BMI of obese patients and controls was 47.3 and 26.5, respectively (p < 0.0001). Arterial hypertension, dyslipidaemia, and smoking were more frequent in the control group than in the obesity group (p < 0.02). The prevalence of CAC was higher in the obesity group (53% vs. 23%, p < 0.01). The groups did not differ regarding CS and CA. However, the difference between coronary age and metrical age was higher in obese patients than in controls (+5.6 vs. –4.8 years, respectively, p < 0.005).

Conclusions

Patients with morbid obesity present an increased risk of CAD that is reflected by the difference between their coronary age and metrical age.

Chest adipose tissue distribution in patients with morbid obesity

Purpose

Obesity is a well-known of risk factor for atherosclerosis and the amount of visceral adipose tissue is considered as an independent predictor of coronary artery disease (CAD). An aim of the study was to investigate the distribution of intrathoracic adipose tissue in morbidly obese patients.

Material and methods

Fifty-one patients with morbid obesity (BMI ≥ 40 kg/m²) and thirty controls were scanned in a coronary calcium scoring protocol. Control group consisted of patients scanned due to a clinical suspicion of CAD, who did not fulfill obesity criteria. The amount of adipose tissue was measured as epicardial adipose tissue (EAT) thickness, pericoronary fat (PCF) thickness, total intra-pericardial fat (IPF) volume, and total intrathoracic fat (ITF) volume.

Results

Mean BMI of obese patients and controls was 47.3 and 26.5, respectively (p < 0.0001). Patients with obesity and controls did not differ with respect to mean EAT, mean PCF, and IPF. However, ITF was lower in obesity group than in control group (268 vs. 332 cm³, respectively; p < 0.03). Moreover, ROC analysis presented relation between obesity and the superior EAT thickness, PCF at LCX, mean PCF, ITF, and chest soft tissue (CST) thickness (p < 0.03). CST thickness of > 60 mm was the parameter that presented the strongest association with morbid obesity (AUC 0.95; p < 0.0001).

Conlcusions

Increased chest soft tissue thickness but not the increased intrathoracic adipose tissue volume was associated with morbid obesity. Since the quantity of the pericardiac fat is not directly related to the obesity, its accumulation may be related to a mechanism different than that of subcutaneous adipose tissue growth.