Non-invasive detection of significant coronary artery disease with multi-section computed tomography angiography in patients with suspected coronary artery disease.

AIM: The objective of this prospective study was to compare the accuracy of multi-section computed tomography (MSCT) coronary angiography with invasive selective coronary angiography in the detection of significant coronary stenosis (> or =50% lumen diameter narrowing). METHODS: Thirty consecutive patients (mean age 59+/-10 years) with suspected coronary artery disease underwent both invasive coronary angiography and MSCT using a 40-section multidetector row machine with temporal resolution of 53ms. Reconstruction images were performed in eight phases of the cardiac cycle. Images of MSCT and invasive coronary angiography were analysed using the 16-segment model of the American Heart Association. RESULTS: A total of 480 segments from 30 patients were evaluated. Coronary segments distal to a vessel occlusion and segments with coronary stent were not considered for analysis (20 segments in total). Ninety-four (20.4%) segments showed significant (> or =50%) stenosis by invasive coronary angiogram. The accuracy of coronary MSCT was computed on a per segment basis. Average sensitivity, specificity, positive predictive value, and negative predictive value of MSCT were 99, 98, 94, and 99%, respectively. CONCLUSION: This study demonstrated that MSCT is as reliable as coronary angiography at detecting significant obstructive coronary artery disease. In selected groups of patients, it may replace the more invasive and potentially more dangerous conventional coronary angiography.

MRI of the fornix and mamillary body in temporal lobe epilepsy.

We performed MRI on 27 patients with clinically proven temporal lobe epilepsy (TLE), all with prior EEG lateralisation, and 10 volunteers, studied to evaluate disparity in size arising from biological variation (group 1). Three-dimensional spoiled GRASS (3DSPGR) sequences provided 2-mm contiguous sections of the limbic system, enabling assessment of the hippocampus (HC), fornix (FN) and mamillary body (MB). Measurements of FN and MB width were made from a workstation. Any percentage difference in size was computed. In 19 cases there was unilateral abnormality in the HC (group 2); in 18 and 19 cases respectively there was a smaller FN and MB on the same side as the abnormal HC. This percentage difference in size was significantly greater than that in group 1 in the FN and MB in 17 and 17 cases respectively. Comparison of percentage difference computations for FN and MB between groups 1 and 2 showed high statistical significance (P < 0.0002). In 5 patients with clinical TLE the HC was normal on MRI (group 3). Unequal FN and MB sizes were found in 4, significant in 2. Comparison of percentage difference computations for FN and MB showed statistical significance (P < 0.0005 and P < 0.0003 respectively). There was no case of discordance between the sides of hippocampal abnormality and the smaller FN or MB or between the sides of smaller FN and MB. The strong concordance between the changes in the HC and those in the FN and MB suggests that this combination will play an important role in the assessment of TLE and limbic system abnormality.

Diagnosis of deep venous thrombosis: accuracy of colour doppler ultrasound compared with venography.

Doppler ultrasound is becoming increasingly accepted as an accurate, non-invasive means of imaging in suspected deep venous thrombosis (DVT). Several studies done abroad have reported (combined) sensitivity of 95% and specificity of 98%. Locally, however, we have still been relying primarily on venography to diagnose lower limb DVT. We performed a prospective study to assess the accuracy of ultrasound compared to venography, in the local context. Forty-one limbs were studied by ultrasound within 24 hours of a venogram examination. We assessed grey-scale appearance, compressibility, presence or absence of flow, and flow characteristics. Seventeen venograms were positive for DVT, and ultrasound was positive in all seventeen cases. There were two false positive ultrasound examinations. Two cases of small localised thrombi in the superficial femoral vein only were accurately detected by ultrasound. One case of isolated calf thrombosis was also successfully diagnosed. Overall, sensitivity and specificity for detection of lower limb DVT was 100% and 91.7% respectively. Overall accuracy was 95.1%.

High resolution computed tomography of the temporal bone: preliminary experience.

High Resolution Computed Tomography (HRCT) can demonstrate the detailed anatomy and pathology of the temporal bone and is fast becoming an important imaging modality in the diagnosis and preoperative management of our local patients with temporal bone diseases. We present our experience in the usage of HRCT in temporal bone lesions in Tan Tock Seng Hospital, using 8 cases as illustration. The protocol that we used to obtain the images is described. We also give an overview of those clinical conditions whereby HRCT can provide information which will help surgeons in the management of their patients. These clinical conditions are hearing loss, external auditory canal atresia, middle ear inflammation/cholesteatoma, temporal bone trauma, pulsatile tinnitus and vascular tympanic membrane.

Preliminary report on ultrasound guided transrectal prostatic biopsy.

Transrectal ultrasound (TRUS)-guided transrectal biopsy was performed on 15 patients. Histological findings were carcinoma in three cases (20%), prostatitis in three cases (20%) and glandular atypia in two cases (13%). All lesions were located in the peripheral zone. Hyperechoic lesions on TRUS were seen in two of the three cases of prostatic carcinoma while hypoechoic lesions were seen in all three cases of prostatitis. Directed biopsies established the diagnosis in six cases. However, random biopsies revealed that the extent of involvement was underestimated in five of these six cases. In addition, random biopsies established the diagnosis in two cases where the directed specimen was negative. Where both digital rectal examination (DRE) and TRUS were positive for nodules and the prostatic specific antigen (PSA) was elevated, the histology was positive in 100%. Where both the DRE and TRUS were negative, the histology was negative irrespective of the PSA level. Patient acceptance of the procedure was high. Complications to the procedure were haematuria, passing blood per rectum and fever.

Basal ganglia calcification on computer tomographic scan. A clinical and radiological correlation.

Computerised tomography of the brain was used to demonstrate basal ganglia calcification which may be of an insufficient degree to be seen on skull X-ray. Cases referred for CT scan from hospitals in Singapore for various reasons over a period of 12 months were studied for basal ganglia calcification. There was a startlingly high incidence of 1.5%, as 47 cases (all except 2 were Chinese) showed such calcification. In 42 cases there was no evidence of basal ganglia calcification on skull X-ray. 16 cases showed neurological affection, fits being the commonest manifestation. An unexpected finding was that no case had abnormality of calcium metabolism or evidence of hypoparathyroidism or pseudohypoparathyroidism. The CT scan is very sensitive in demonstrating minimal basal ganglia calcification and our impression is that such calcification is common.

Cerebral metastasis in bronchial carcinoma.

A prospective study of 61 consecutive cases of bronchial carcinoma was done to detect cerebral metastasis and study their clinical presentations. Computerised tomography (CT Scan) was utilised as a screening procedure in 36 cases along with electroencephalography to detect cerebral secondaries. Of the cases studied with CT Scan and autopsy, 55% had brain secondaries. 18% of these cases had silent cerebral secondaries. 30% of the 61 cases studied has signs and symptoms referable to brain secondaries. An interesting clinical presentation was a dysequilibrium which in many of them was an extreme truncal ataxia, confining them helplessly to bed and relieved to some extent by a shunt operation.