Biomedical subjects

C R Bellina

Publications and source records attributed to C R Bellina.

32 records · Page 2Linked to original sources

PubMed1988

Performance characteristics of a whole-body positron tomograph.

This paper describes an investigation of some of the important physical characteristics of a whole-body positron tomograph consisting of two rings of bismuth germanate detectors of dimensions 5.6 mm X 30 mm X 30 mm (512/ring). The resolution applicable to in vivo imaging is six mm or more, depending on radionuclide and reconstruction filter and is very uniform over the field of view normally used. Axial resolution can be varied by moving side collimation (maximum approximately 16 mm FWHM with interplane septa). A simple scheme has been devised to correct for loss of true coincidence events with varying count rate based on the total random and multiple coincidence rates. It is concluded that correction for scattered radiation should be implemented for reliable quantitation.

Humans↗

PubMed1984

Pleural liquid pressure gradients and intrapleural distribution of injected bolus.

In supine anesthetized dogs we measured pleural liquid pressure (Pliq) in mediastinal, diaphragmatic, apical, and costal regions at different lung heights during eupneic breathing. At end expiration and at a given height, Pliq was similar in the costal and apical regions, but it was lower in the diaphragmatic and mediastinal compartments. Inspiratory swings toward lower values were progressively greater with increasing height and moving from costal to apical, diaphragmatic and mediastinal compartments. Thus during inspiration, at any height, the costomediastinal and costodiaphragmatic Pliq difference increased while a costoapical difference developed. One minute after injection of 0.5-1 ml of saline at different points within the cavity, end-expiratory liquid pressure became higher on the average by 0.45, 1.55, and 0.55 cmH2O in the apical, mediastinal, and diaphragmatic compartments, respectively, while no change was observed on costal side. These results suggested liquid accumulation in the compartments displaying a lower Pliq. This was confirmed by following, with a gamma camera, on a frontal projection of the lung, the intrapleural distribution of a bolus containing 99mTc-labeled albumin injected at various places.

Animals↗

PubMed1984

An electronic "diaphragm" for the gamma camera, with adjustable zooming and offset.

We describe a new device for data acquisition from a gamma camera using an electronic spatial "diaphragm," with variable offset and zooming. The device, mainly applied to cardiac studies, permits selection of the desired part of the field of vision to be digitized and to zoom, before the computer acquisition. The spatial diaphragm spans 0.4-0.9 of the diameter of the FOV, and the amplification factor from 1.1 to 2.5.

Computers↗

PubMed1980

CAMIRD/III: a revised version of the CAMIRD/II and MIRD-S packages for internal dose calculation: concise communication.

We describe the characteristics of the CAMIRD/III, a software package for the calculation of radiation dose from internally distributed radionuclides. The work concerns the preparation of a revised version of both CAMIRD/II, which uses prestored data of the specific absorbed-energy fraction, and MIRD-S, which uses the precalculated "S" values. Some improvement in the dose computation has been realized, for instance in the case of organs with walls, The software, written in FORTRAN IV, runs on an IBM 370/168 computer.

Computers↗

PubMedDate not supplied

Incremental diagnostic value of dipyridamole echocardiography and exercise thallium 201 scintigraphy in the assessment of presence and extent of coronary artery disease.

BACKGROUND: The incremental diagnostic information of two noninvasive tests for the detection of coronary artery disease (CAD), dipyridamole echocardiography, and exercise 201Tl myocardial scintigraphy was assessed in a series of 102 patients with ordered logistic regression and receiver-operating characteristic curves. METHODS AND RESULTS: Patients were selected from those referred to our cardiovascular centers with the clinical suspicion of CAD. After clinical evaluation, all patients underwent both noninvasive tests during hospitalization 2 weeks before coronary arteriography. The coronary arteriogram was used as a gold standard: CAD was defined as the presence of one or more vessels with 50% or greater narrowing of the luminal diameter. Clinical data were 73.0% +/- 5.7% accurate in the prediction of CAD. The addition of dipyridamole echocardiographic data to the clinical model yielded a diagnostic accuracy of 88.3% +/- 4.3% (p < 0.00001), whereas the addition of thallium scintigraphic parameters to the clinical model improved diagnostic accuracy to 93.8% +/- 2.6% (p < 0.00001). A significant increase in accuracy to 97.2% +/- 1.4% was achieved when thallium scintigraphic data were added to the clinical and dipyridamole-echocardiographic model (p < 0.00001). CONCLUSION: Both noninvasive methods for detection of CAD, DET, and ETS showed a good diagnostic accuracy especially when tests-derived parameters were combined with clinical data by means of relative logistic models; nevertheless the ETS model showed a higher sensitivity in comparison with the DET model, essentially in presence of a lower extent of CAD.

Adult↗

PubMedDate not supplied

Incremental diagnostic value of dobutamine stress echocardiography and dobutamine scintigraphy (technetium 99m-labeled sestamibi single-photon emission computed tomography) for assessment of presence and extent of coronary artery disease.

BACKGROUND: The incremental diagnostic value of dobutamine stress echocardiography (DSE) and 99mTc-labeled sestamibi single-photon emission computed tomography for the evaluation of the presence and extent of coronary artery disease (CAD) was assessed with ordered logistic regression and receiver-operating characteristic curves. METHODS AND RESULTS: Forty-five consecutive patients (33 men and 12 women; 53 +/- 6.8 years) underwent exercise electrocardiography and simultaneous DSE and sestamibi single-photon emission computed tomographic imaging. Coronary angiography was performed in all patients (significant coronary stenosis > 50%). On the basis of the results of exercise electrocardiography, the pretest probability for CAD (Diamond's algorithm) was low (45.6% +/- 12.7%). According to ordered logistic regression analysis, some models were estimated that performed a diagnostic accuracy level for CAD. In particular, we evaluated a clinical model (model 1) determined by the following parameters: sex, age, presence of chest pain, and positivity of electrocardiogram during dobutamine stress test. This model was 64.3% +/- 10.7% accurate for the prediction of CAD. The addition to model 1 of DSE parameters (wall motion stress and rest score index and relative difference) (model 2) yielded a diagnostic accuracy of 81.4% +/- 4.3% (p < 0.045), whereas the addition to model 1 of single-photon emission computed tomographic parameters (the difference between perfusional stress and rest score index) (model 3) improved diagnostic accuracy to 92.3% +/- 5.5% (p < 0.003), a level that appeared significantly higher than that of model 2 (p < 0.016). CONCLUSION: Both noninvasive methods for the detection of CAD showed a good diagnostic accuracy, especially when test-derived parameters were combined with clinical data. Nevertheless, the single-photon emission computed tomographic model showed a higher sensitivity compared with the DSE model.

Adult↗

PubMedDate not supplied

Detection of melanoma cells in peripheral blood and sentinel lymph nodes by RT-PCR analysis: a comparative study with immunohistochemistry.

The presence of lymph node metastases is the best prognostic factor for predicting relapse or survival in melanoma patients. It has been demonstrated that melanoma metastases spread through the first lymph node(s) draining the tumor (sentinel lymph node, SN) to the lymphatic system and that detection of melanoma cells in peripheral blood directly correlates with prognosis in melanoma. To identify lymph node metastases and circulating melanocytes, we developed a single-step reverse transcriptase-polymerase chain reaction assay (RT-PCR) for detection of two melanoma-specific markers: the tyrosinase gene, which encodes an enzyme associated with melanin synthesis, and melanoma antigen-related T-cells, which are present in tumor infiltrating T-lymphocytes. This method detects two tumor cells in a background of 10(7) lymphocytes. Thirty patients with stage I-IV cutaneous melanoma entered the study. Blood samples were taken preoperatively, one month after excision of the primary melanoma lesion and the SN or total lymphadenectomy, and before the start of chemotherapy and every three months thereafter in metastatic patients. SNs were collected from 22 patients, bisected and analyzed by RT-PCR and routine pathological and immunohistochemical tests. The preliminary results indicate that RT-PCR for melanoma markers is a sensitive and valuable method for the detection of micrometastases and for early diagnosis and staging of melanoma.

Adult↗

PubMedDate not supplied

Gamma probe-guided thoracoscopic surgery of small pulmonary nodules.

Video-assisted thoracic surgery (VATS) is an interesting and emerging procedure for the diagnosis and treatment of peripheral pulmonary nodules. We developed a new radioguided surgical technique for the detection during VATS of pulmonary nodules smaller than 2 cm, situated deep in the lung parenchyma and neither visible nor palpable with endoscopic instruments. The procedure is divided into two phases. Two hours before surgery 0.3 ml of a solution composed of 0.2 mL of 99mTc-labeled human serum albumin microspheres (5-10 MBq) and 0.1 mL of non-ionic contrast is injected into the lesion under CT guidance. Then the patient is submitted to VATS. During thoracoscopy a collimated probe of 11 mm diameter connected to a gamma ray detector is introduced via an 11.5 mm trocar and the pleural surface of the suspected area is scanned. A hot spot indicates the presence of the radiolabeled nodule and hence the area to be resected. We treated 39 patients with small pulmonary nodules (mean size, 8.3 mm; range, 4-19 mm). The patients were 27 men and 12 women (mean age, 60.8 years; range, 13-80 years). Nineteen patients had a history of synchronous or metachronous malignancy. In all cases the nodule was detected and resected and the resection margins were pathologically free of tumor. Histological examination showed 21 benign and 18 malignant lesions (7 metastases and 11 primary lung cancers). Nine patients with a frozen section-based histopathological diagnosis of lung cancer without functional contraindications underwent a completion lobectomy by open surgery in the same surgical session. In conclusion, the radiolocalization of small pulmonary nodules by gamma probe during VATS is a safe and easy procedure, with fewer complications and a lower failure rate than other localization techniques.

Adolescent↗

PubMedDate not supplied