Is a lung perfusion scan obtained by using single photon emission computed tomography able to improve the radionuclide diagnosis of pulmonary embolism?

Planar pulmonary scintigraphy is still regularly performed for the evaluation of pulmonary embolism (PE). However, only about 50-80% of cases can be resolved by this approach. This study evaluates the ability of tomographic acquisition (single photon emission computed tomography, SPECT) of the perfusion scan to improve the radionuclide diagnosis of PE. One hundred and fourteen consecutive patients with a suspicion of PE underwent planar and SPECT lung perfusion scans as well as planar ventilation scans. The final diagnosis was obtained by using an algorithm, including D-dimer measurement, leg ultrasonography, a V/Q scan and chest spiral computed tomography, as well as the patient outcome. A planar perfusion scan was considered positive for PE in the presence of one or more wedge shaped defect, while SPECT was considered positive with one or more wedge shaped defect with sharp borders, three-plane visualization, whatever the photopenia. A definite diagnosis was achieved in 70 patients. After exclusion of four 'non-diagnostic' SPECT images, the prevalence of PE was 23% (n =15). Intraobserver and interobserver reproducibilities were 91%/94% and 79%/88% for planar/SPECT images, respectively. The sensitivities for PE diagnosis were similar for planar and SPECT perfusion scans (80%), whereas SPECT had a higher specificity (96% vs 78%; P =0.01). SPECT correctly classified 8/9 intermediate and 31/32 low probability V/Q scans as negative. It is concluded that lung perfusion SPECT is readily performed and reproducible. A negative study eliminates the need for a combined V/Q study and most of the 'non-diagnostic' V/Q probabilities can be solved with a perfusion image obtained by using tomography.

Use of DNA restriction fragment typing in the differentiation of Mycobacterium tuberculosis complex isolates from animals and humans in Burundi.

SETTING: Bubanza Hospital and Veterinary Laboratory in Bujumbura, Burundi. OBJECTIVE: To monitor the rate of Mycobacterium bovis infections among tuberculosis (TB) patients and among slaughtered cattle, and to analyse the polymorphism among deoxyribonucleic acid (DNA) fingerprints of the M. tuberculosis complex isolates. DESIGN: 135 lymph node biopsies and 35 sputum specimens from human patients, together with specimens from 46 healthy animals and 36 animals suspected for bovine tuberculosis (BTB), were cultured. Isolates were identified phenotypically and DNA fingerprints were obtained by IS6110 based restriction fragment length polymorphism. RESULTS: 119 M. tuberculosis complex isolates were obtained from 170 human specimens. M. bovis was not identified in any human sample. One out of 46 healthy animals and 14 out of 36 BTB suspected animals yielded M. bovis isolates. DNA fingerprinting revealed four to eight copies of IS6110 for all M. bovis isolates with some degree of polymorphism, and some clustering for human TB isolates. No relationship was observed between human and bovine isolates. CONCLUSION: At present M. bovis seems to play a minor role in human TB in Burundi, despite the high prevalence of both human immunodeficiency virus infection in humans and M. bovis in cattle. DNA fingerprinting is able to differentiate between bovine isolates.

Rapid, early and specific diagnosis of tuberculosis and other mycobacterial diseases in Burundi.

The potential usefulness of ELISA based serological tests to assist in rapid, early and specific diagnosis of tuberculosis was investigated. The materials were selected, based on published data and on our preliminary findings. Initially screening tests were performed using crude antigens such as Purified Protein Derivate (PPD) and a BCG-filtrate. Unfortunately, the results with these antigens were not promising. The specificity of both antigens using sera from 94 healthy controls was 64%. As a consequence of these findings, the crude antigens were excluded from further tests, and the study was continued with purified antigens. The work focused on 2 purified proteins: Antigen 60 (A60), a lipopolysaccharide-protein complex, and P32, a stress protein produced in zinc deprived cultures, identified as Antigen 85 A in the BCG reference system, both isolated from Mycobacterium bovis BCG. The commercial A60 based ELISA and our own P32 based ELISA were used to test a total of 300 sera from HIV positive, negative and unscreened individuals, mainly originating from Burundi. These sera were collected from clinical established cases of pulmonary TB, extrapulmonary TB, and patients with non-tuberculous tropical diseases such as salmonellosis, trypanosomiasis, malaria, etc. and healthy individuals. The A60 based ELISA had a sensitivity of 76.8% for the proven cases of active pulmonary tuberculosis and 61.9% for the extrapulmonary tuberculosis cases. No difference was shown between HIV positive and HIV negative patients. Specificity reached 95.2% for healthy individuals, but dropped to 68.1% when persons with active non-tuberculous tropical diseases were included. Eighty-six percent of the pulmonary cases and 87.7% of the extrapulmonary cases were detected by the ELISA-P32. These findings suggest that this test might be useful as a confirmatory test for the diagnosis of extrapulmonary tuberculosis. Again no difference was noticed between HIV negative and positive patients. The main contraindication for the use of the ELISA-P32 for the diagnosis of tuberculosis is its low specificity: 70.2% with sera from healthy controls and 22.2% for hospitalised patients and persons with non-tuberculous tropical diseases. In a small recent prospective study 4 out of 10 HIV+ persons with no evidence for TB yielded a positive result for the ELISA-P32. Two of them developed pulmonary tuberculosis within 6 months, whereas 2 P32-positives and 6 P32-negatives remained up to now without any manifestations of tuberculosis. The difference was not significant, but the number of cases was limited.(ABSTRACT TRUNCATED AT 400 WORDS)