Paulo Schiavom Duarte

Exclusion of chronic osteomyelitis with F-18 fluorodeoxyglucose positron emission tomographic imaging

PURPOSE Excluding the diagnosis of chronic osteomyelitis is often difficult with noninvasive techniques, especially when bone anatomy and structure have been altered by trauma, surgery, or soft-tissue infection. It has been reported that fluorodeoxyglucose (FDG) positron emission tomography (PET) has excellent potential to diagnose osteomyelitis. In this study, the accuracy of FDG PET in the diagnosis of chronic osteomyelitis was determined. METHOD Twenty-two patients with possible osteomyelitis (5 in the tibia, 5 in the spine, 4 in the proximal femur, 4 in the pelvis, 2 in the maxilla, and 2 in the feet) who underwent FDG PET imaging and on whom operative or clinical follow-up data were available were included in this analysis. The final diagnosis was made by surgical exploration or clinical follow-up during a 1-year period. RESULTS FDG PET correctly diagnosed the presence or absence of chronic osteomyelitis in 20 of 22 patients. Six had chronic osteomyelitis and 16 proved to be free of osteomyelitis. FDG PET correctly identified all six patients with chronic osteomyelitis but produced two false-positive results. This study had a sensitivity rate of 100%, a specificity rate of 87.5%, and an accuracy rate of 90.9%. CONCLUSION FDG PET is a highly effective imaging method to exclude osteomyelitis when a negative scan result is obtained. However, positive results can be caused not only by true osteomyelitis but also by inflammation in the bone or surrounding soft tissues as a result of other causes. Overall, FDG PET may prove to be the preferred study in the management of patients with possible chronic osteomyelitis.

Rapid normalization of osseous FDG uptake following traumatic or surgical fractures

It is known that following a traumatic fracture or surgical intervention, bone scintigraphy reveals positive results for an extended period of time, posing a challenge when evaluating patients for possible malignancy or superimposed osteomyelitis. Previous reports indicate that acute fractures can also result in increased fluorine-18 fluorodeoxyglucose (FDG) accumulation and therefore cause difficulties when patients are evaluated for other indications by FDG-PET. The purpose of this study was to assess the pattern and time course of abnormal FDG uptake following traumatic or surgical fracture. A total of 1,517 consecutive patients who underwent whole-body FDG-PET imaging were retrospectively studied. A history of fractures or orthopedic intervention was obtained from an interview prior to scanning. The FDG-PET results were compared with the results of other imaging studies, including bone scans, radiographs, CT, and MRI, as well as surgical pathology reports. Thirty-seven patients with a known date of traumatic or surgical fracture were identified. Among these, 14 had fractures or surgery within 3 months prior to FDG-PET, while 23 had fractures or surgical intervention greater than 3 months prior to FDG-PET. FDG-PET showed no abnormally increased uptake at the known fracture or surgical sites in 30 of these patients. Notably, in the 23 patients with fractures more than 3 months old, all but one showed no abnormally increased uptake. Furthermore, the positive FDG uptake in this exception was a result of complicating osteomyelitis. In the 14 patients with a history of fracture less than 3 months old, only six had abnormally increased FDG uptake. Following traumatic or surgical fractures, FDG uptake is expected to be normal within 3 months unless the process is complicated by infection or malignancy.

The receiver operating characteristic curve for the standard uptake value in a group of patients with bone marrow metastasis.

PURPOSE The aim of this work was to determine the standard uptake value (SUV) threshold for differentiating malignant from benign bone lesions. MATERIAL AND METHODS Ninety-nine bone sites in 33 patients who had undergone a 2-deoxy-2-[18F]fluoro-D-glucose-positron emission tomography (FDG-PET) study for cancer evaluation were studied. In addition to FDG-PET, a bone scan and at least two of the following determinations: magnetic resonance imaging (MRI), computed tomography (CT), and x-ray were conducted in each patient. The bone lesions were considered positive for malignancy if confirmed by clinical follow-up or a high degree of suspicion based on the positive results of at least three (which must include bone scan) out of four other imaging modalities. By these criteria, 39 lesions were considered positive and 60 were considered negative. The SUV values were classified as positive or negative using 61 different values of threshold (range from 1.0 to 7.0). These results were compared with the positive criteria above and reclassified as true positive, true negative, false positive, and false negative. The true-positive fraction and false-positive fraction were calculated for each threshold value. The receiver operating characteristic (ROC) curve was drawn and the best value was determined by visual analysis. RESULTS The SUV threshold was considered 2.5. Twenty-nine out of 39 bone lesions classified as positive showed a SUV > 2.5. Of the 10 false-negative lesions, seven showed a SUV between 1.1 and 2.0, and three were not detected. Fifty-six out of 60 lesions classified as negative showed a SUV < 2.5. Four lesions were false positive: one was a rib fracture and three were severe degenerative changes in the lumbar spine. Using an SUV threshold of 2.5, the sensitivity was 74.3% and the specificity was 93.3%. CONCLUSION In our patient population, the optimal SUV to classify a bone lesion as malignant or benign is 2.5.

Comparison of relative renal function measured with either 99mTc-DTPA or 99mTc-EC dynamic scintigraphies with that measured with 99mTc-DMSA static scintigraphy

OBJECTIVE The aim of this study was to compare the renal function measured with either 99mTc-DTPA or 99mTc-EC dynamic scintigraphies with that measured using 99mTc-DMSA static scintigraphy. METHODS the values of relative renal function measured in 111 renal dynamic scintigraphies performed either with 99mTc-DTPA (55 studies) or with 99mTc-EC (56 studies) were compared with the relative function measured using 99mTc-DMSA static scintigraphy performed within a 1-month period. The comparisons were performed using Wilcoxon signed rank test. The number of 99mTc-DTPA and 99mTc-EC studies that presented relative renal function different by more than 5% from that measured with 99mTc-DMSA, using chi square test were also compared. RESULTS the relative renal function measured with 99mTc-EC is not statistically different from that measured with 99mTc-DMSA (p = 0.97). The relative renal function measured with 99mTc-DTPA was statistically different from that measured using 99mTc-DMSA, but with a borderline statistical significance (p = 0.05). The number of studies with relative renal function different by more than 5% from that measured with 99mTc-DMSA is higher for the 99mTc-DTPA scintigraphy (p = 0.04) than for 99mTc-EC. CONCLUSION the relative renal function measured with 99mTc-EC dynamic scintigraphy is comparable with that measured with 99mTc-DMSA static scintigraphy, while the relative renal function measured with 99mTc-DTPA dynamic scintigraphy presents a significant statistical difference from that measured with 99mTc-DMSA static scintigraphy.

Pulmonary clostridium perfringens infection detected by FDG positron emission tomography.

Clostridium perfringens is an anaerobic, Gram-positive, spore-forming rod that is widely distributed in the environment. It commonly causes food poisoning. Rarely, it can also cause enteritis necroticans, which is more severe. However, C. perfringens infection of the lung has not been reported. The authors present a case of pulmonary infection of C. perfringens with increased fluorodeoxyglucose (FDG) accumulation that was interpreted as cancer. This case not only highlights C. perfringens infection as a cause of false-positive result in the evaluation of lung nodule but also indicates that the development of FDG positron emission tomographic (PET) technology will increase our understanding of other diseases.

Clinical significance of transient left ventricular dilation assessed during myocardial Tc-99m sestamibi scintigraphy

OBJECTIVE To assess the clinical significance of transient ischemic dilation of the left ventricle during myocardial perfusion scintigraphy with stress/rest sestamibi. METHODS The study retrospectively analyzed 378 patients who underwent myocardial perfusion scintigraphy with stress/rest sestamibi, 340 of whom had a low probability of having ischemia and 38 had significant transient defects. Transient ischemic dilation was automatically calculated using Autoquant software. Sensitivity, specificity, and the positive and negative predictive values were established for each value of transient ischemic dilation. RESULTS The values of transient ischemic dilation for the groups of low probability and significant transient defects were, respectively, 1.01 0.13 and 1.18 0.17. The values of transient ischemic dilation for the group with significant transient defects were significantly greater than those obtained for the group with a low probability (P<0.001). The greatest positive predictive values, around 50%, were obtained for the values of transient ischemic dilation above 1.25. CONCLUSION The results suggest that transient ischemic dilation assessed using the stress/rest sestamibi protocol may be useful to separate patients with extensive myocardial ischemia from those without ischemia.

Lógica fuzzy e regressão logística na decisão para prática de cintilografia das paratiróides

OBJETIVO: Desenvolver e comparar dois modelos matematicos, um deles baseado em regressao logistica e o outro em teoria de conjuntos fuzzy, para definir a indicacao para a realizacao do exame cintilografico a partir de resultados dos exames laboratoriais. METODOS: Foram identificados 194 pacientes que tiveram calcio e paratormonio sericos medidos a partir da base de registros de cintilografia de paratiroides realizadas em laboratorio de diagnostico de Sao Paulo, no periodo de janeiro de 2000 a dezembro de 2004. O modelo de regressao logistica foi desenvolvido utilizando-se o software SPSS e o modelo fuzzy, o Matlab. A performance dos modelos foi comparada utilizando-se curvas ROC. RESULTADOS: Os modelos apresentaram diferencas estatisticamente significantes (p=0,026) nos seus desempenhos. A area sob a curva ROC do modelo de regressao logistica foi de 0,862 (IC 95%: 0,811-0,913) e do modelo de logica fuzzy foi 0,887 (IC 95%: 0,840-0,933). Este ultimo destacou-se como particularmente util porque, ao contrario do modelo logistico, mostrou capacidade de utilizar informacoes de paratormonio em intervalo em que os valores de calcio mostraram-se pouco discriminantes. CONCLUSOES: O modelo matematico baseado em teoria de conjuntos fuzzy pareceu ser mais adequado do que o baseado em regressao logistica como metodo para decisao da realizacao de cintilografia das paratiroides. Todavia, sendo resultado de um exercicio metodologico, inferencias sobre o comportamento do objeto podem ser improprias, dada a nao representatividade populacional dos dados.

Selection of patients for myocardial perfusion scintigraphy based on fuzzy sets theory applied to clinical-epidemiological data and treadmill test results

Coronary artery disease (CAD) is a worldwide leading cause of death. The standard method for evaluating critical partial occlusions is coronary arteriography, a catheterization technique which is invasive, time consuming, and costly. There are noninvasive approaches for the early detection of CAD. The basis for the noninvasive diagnosis of CAD has been laid in a sequential analysis of the risk factors, and the results of the treadmill test and myocardial perfusion scintigraphy (MPS). Many investigators have demonstrated that the diagnostic applications of MPS are appropriate for patients who have an intermediate likelihood of disease. Although this information is useful, it is only partially utilized in clinical practice due to the difficulty to properly classify the patients. Since the seminal work of Lotfi Zadeh, fuzzy logic has been applied in numerous areas. In the present study, we proposed and tested a model to select patients for MPS based on fuzzy sets theory. A group of 1053 patients was used to develop the model and another group of 1045 patients was used to test it. Receiver operating characteristic curves were used to compare the performance of the fuzzy model against expert physician opinions, and showed that the performance of the fuzzy model was equal or superior to that of the physicians. Therefore, we conclude that the fuzzy model could be a useful tool to assist the general practitioner in the selection of patients for MPS.

Increased FDG uptake in the right cardiac chambers in a patient with pulmonary emphysema.

A solitary lung node was identified on a computed tomographic (CT) scan in a 62-year-old man with severe pulmonary hypertension and emphysema who was enrolled in a lung transplant program. Aspiration biopsy confirmed the presence of a pulmonary adenocarcinoma in the right middle lobe. A fluorodeoxyglucose (FDG) positron emission tomographic (PET) study was performed to stage the disease. In addition to the known lung cancer, significantly increased FDG uptake in the right atrium, right ventricle, and interventricular septum were noted.

Multiple intraabdominal soft-tissue masses in a man awaiting liver transplantation: A case study and discussion

An unusual cause of abdominal soft-tissue masses is accessory splenic tissue. The Tc-99m-sulfur colloid liver–spleen scan is a valuable adjunct in making this diagnosis. This report describes a 47-year-old man who had an abdominal magnetic resonance imaging (MRI) scan as part of a pretransplant evaluation and was found to have multiple soft-tissue masses in the posterior aspect of his abdomen. His history was pertinent for a traumatic rupture of the spleen at the age of 12 years, for which he required a splenectomy. He had no symptoms or physical findings to indicate a lymphoproliferative disorder or other malignant process. His peripheral blood smear was remarkable for the absence of Howell-Jolly bodies. The nuclear scan confirmed the presence of uptake in the soft-tissue masses seen on MRI scan. This finding supports our diagnosis of splenosis in a man with a history of traumatic splenic rupture as a child.