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Biomedical subjects

S N Chatziioannou

Publications and source records attributed to S N Chatziioannou.

7 recordsLinked to original sources
PubMed2001

The role of radionuclides in primary musculoskeletal tumors beyond the 'bone scan'.

Radionuclides represent a means of functional imaging, which is able to reflect the metabolic state of tissues. Recently developed radiotracers and older radiotracers with newer applications, imaged through single photon emission computed tomography (SPECT) and positron emission tomography (PET), can provide significant information in the diagnosis, grading, therapy response or recurrence of primary musculoskeletal tumors. The unique ability of these radiotracers to demonstrate non-invasively the efflux pump rate, which is a common reason of therapy failure, as well as the metabolic and proliferative rates of the tumors should be a powerful tool in the orthopaedic oncology in the evaluation of musculoskeletal tumors.

Bone Neoplasms↗
PubMed2000

Hepatobiliary scintigraphy is superior to abdominal ultrasonography in suspected acute cholecystitis.

BACKGROUND: Hepatobiliary scintigraphy is a very accurate test in the diagnosis of acute cholecystitis. However, ultrasonography is extensively used for the diagnosis of this disease. In this study, we directly compare the diagnostic accuracy of these techniques for acute cholecystitis. MATERIALS AND METHODS: The diagnostic accuracy of scintigraphy and ultrasonography was evaluated in 107 consecutive patients with suspected acute cholecystitis who underwent both imaging modalities within one day. The incremental diagnostic value of each modality was determined. RESULTS: The sensitivity, specificity, positive and negative predictive values, and accuracy for the diagnosis of acute cholecystitis in the entire cohort were superior for scintigraphy compared with ultrasonography. The accuracy was 92% for scintigraphy and 77% for ultrasonography. Similarly, if only surgically treated patients were considered, the accuracy of scintigraphy was 91% versus 61% for ultrasonography. The diagnostic value of scintigraphy for the entire cohort was significantly superior to ultrasonography (global, chi(2) = 58.1 vs 9.7, respectively); the addition of the information derived from the latter did not further improve the diagnostic value of scintigraphy (global, chi(2) = 58.2). CONCLUSIONS: Hepatobiliary scintigraphy has superior diagnostic accuracy for acute cholecystitis compared with ultrasonography. The addition of ultrasonography does not further improve the diagnostic accuracy of scintigraphy alone.

Acute Disease↗
PubMed2000

Indium-111 leukocyte scintigraphy in suspected bowel ischemia.

OBJECTIVE: The purpose of this study was to evaluate the utility of indium-111 leukocyte (In-111 WBC) scintigraphy in a large number of patients with suspected bowel ischemia. METHODS: All patients who underwent In-111 WBC scintigraphy for possible bowel ischemia over a 4-yr period and had subsequent endoscopic or surgical biopsy were retrospectively evaluated. Early (1-4 h postinjection) and late (18-24 h postinjection) images were obtained. Any study with tracer activity in the bowel on early or late images was considered positive for bowel ischemia. RESULTS: Fifty-nine patients were included in the analysis. In-111 WBC scintigraphy detected 23 of 24 cases of bowel ischemia (sensitivity = 96%). Of 35 cases without ischemia, 16 had a negative In-111 WBC scintiscan (specificity = 46%). Negative and positive predictive values for the diagnosis of bowel ischemia were 94% and 55%, respectively. Of the 19 cases without bowel ischemia and a positive scintiscan, 15 had another intraabdominal process responsible for the patients' symptomatology. CONCLUSIONS: In-111 WBC scintigraphy is a highly sensitive diagnostic tool for bowel ischemia. A normal In-111 WBC scintiscan strongly suggests that this disease is not present.

Aged↗
PubMed2000

Gating of myocardial perfusion imaging for the identification of artifacts: is it useful for experienced physicians?

Gating of myocardial perfusion imaging helps to differentiate artifacts from perfusion defects. We used this technique to evaluate the impact of routine gating on the interpretation of results by physicians experienced in this field. We studied, prospectively, 270 consecutive patients (161 men and 109 women) who underwent gated myocardial perfusion imaging. Single-photon emission-computed tomography was performed to evaluate myocardial perfusion in patients at rest and after stress, using technetium-99m sestamibi and post-stress gating. Participating physicians interpreted each study and indicated a confidence level for the interpretation. Initially, these opinions were formed on the basis of static slices alone and subsequently, with the addition of gating information. The impact of gating was evaluated by the number of studies in which gating led to a change in interpretation from normal to abnormal or vice versa, or from borderline to definite. The interpretation was changed from abnormal to normal or vice versa in 10 studies (3.7%) and from borderline to definite in 3 (1.1%). In 37 studies (13. 7%), the confidence level was increased from confident to very confident with no change in interpretation. We conclude that routine gating of every myocardial perfusion imaging study for the identification of artifacts is of low value for physicians experienced in interpreting such studies. Although gating frequently increases the confidence level, it seldom leads to a change in interpretation. Specific subgroups of patients who would benefit from gating should be identified.

Aged↗
PubMed1999

Prognostic value of myocardial perfusion imaging in patients with high exercise tolerance.

BACKGROUND: Although high exercise tolerance is associated with an excellent prognosis, the significance of abnormal myocardial perfusion imaging (MPI) in patients with high exercise tolerance has not been established. This study retrospectively compares the utility of MPI and exercise ECG (EECG) in these patients. METHODS AND RESULTS: Of 388 consecutive patients who underwent exercise MPI and reached at least Bruce stage IV, 157 (40.5%) had abnormal results and 231 (59.5%) had normal results. Follow-up was performed at 18+/-2.7 months. Adverse events, including revascularization, myocardial infarction, and cardiac death, occurred in 40 patients. Nineteen patients had revascularization related to the MPI results or the patient's condition at the time of MPI and were not included in further analysis. Seventeen patients (12.2%) with abnormal MPI and 4 (1.7%) with normal MPI had adverse cardiac events (P<0.001). Cox proportional-hazards regression analysis showed that MPI was an excellent predictor of cardiac events (global chi2=13.2; P<0.001; relative risk=8; 95% CI=3 to 23) but EECG had no predictive power (global chi2=0.05; P=0.8; relative risk=1; 95% CI=0.4 to 3.0). The addition of Duke's treadmill score risk categories did not improve the predictive power of EECG (global chi2=0.17). The predictive power of the combination of EECG (including Duke score categories) and MPI was no better than that of MPI alone (global chi2=13.5). CONCLUSIONS: Unlike EECG, MPI is an excellent prognostic indicator for adverse cardiac events in patients with known or suspected CAD and high exercise tolerance.

Adult↗
PubMed1999

The significance of incidental noncardiac findings in Tc-99m sestamibi myocardial perfusion imaging: illustrated by a case.

Technetium 99m sestamibi is widely used in the evaluation of myocardial perfusion imaging. Although the aim of such imaging is cardiac evaluation, numerous other organs are included in the imaging field. Failure to identify incidental abnormal findings in these organs delays diagnosis and treatment. In common with other radiopharmaceutical agents, technetium 99m sestamibi is distributed throughout the body and accumulates in multiple tissues. When interpreting studies that involve this radiotracer, the physician must be aware of its physiologic distribution, in order to recognize abnormal uptake. We present an illustrative case in which areas of decreased tracer activity were noted incidentally during the evaluation of unprocessed single photon emission computed tomography data. These findings were due to metastasis of colon cancer to the liver.

Adenocarcinoma, Mucinous↗