Can infections be imaged in implanted devices?

Approximately 30,000 to 60,000 patients per year in the United States are candidates for heart transplants, mechanical assist devices, or both. These procedures, devices, and the associated short- and long-term care required are expensive and command significant utilization of health care resources. Because device related infection and thrombosis are potentially devastating complications of implanted device utilization, early diagnosis of infection, thrombosis, or both, would be helpful for initiation of early therapy to prevent untoward clinical events. Therefore, the development of a robust imaging technology for identification of infection could be cost effective if early assessment, diagnosis, and therapy of infected devices led to improvements in morbidity and mortality.

Prognostic value of dipyridamole thallium imaging after acute myocardial infarction in older patients.

OBJECTIVE: To assess the utility of intravenous dipyridamole thallium testing for predicting major cardiac events following acute myocardial infarction in older patients. DESIGN: Prospective cohort study with a median follow-up of 18 months. SETTING: A university teaching hospital. PARTICIPANTS: 73 patients aged 65 years and older with enzymatically confirmed acute myocardial infarction (mean age 75 years, 56% male, 71% white). MEASUREMENTS: All patients underwent a detailed clinical assessment, an echocardiogram, and an intravenous dipyridamole thallium stress test before hospital discharge. The study endpoint was death or nonfatal reinfarction during the follow-up period. RESULTS: Overall, 24 patients (33%) died or developed recurrent myocardial infarction during follow-up. Among 44 patients with a reversible thallium defect, 19 (43%) reached the study endpoint, compared with only five of 29 patients (17%) without reversible ischemia (P = .04). On multivariate analysis, independent prognostic variables included non-use of aspirin at hospital discharge (P = .002), decreased left ventricular systolic function (P = .009), non-use of a beta-blocker at hospital discharge (P = .013), and reversible ischemia on thallium scintigraphy (P = .025). The relative risks for death or reinfarction associated with non-use of aspirin, non-use of a beta-blocker, left ventricular dysfunction, and reversible ischemia were 2.65, 2.39, 2.01, and 2.51, respectively. Patients with three or four of these risk factors had an 83% probability of death or reinfarction, compared with 41% in patients with two risk factors and 6% in patients with one or no risk factor (P < .001). CONCLUSION: Intravenous dipyridamole thallium imaging provides independent prognostic information in older patients with acute myocardial infarction. Moreover, the combination of clinical, echocardiographic, and dipyridamole thallium variables effectively stratifies older postinfarction patients into high-, intermediate-, and low-risk categories for death or recurrent myocardial infarction.

Perfusion scintigraphy in the evaluation for lung volume reduction surgery: correlation with clinical outcome.

PURPOSE: To identify preoperative pulmonary perfusion scintigraphic findings that might be associated with clinical outcomes after lung volume reduction surgery. MATERIALS AND METHODS: Preoperative perfusion scintigrams in 103 patients (56 men, 47 women; age range, 41-76 years; mean age, 61 years +/- 9) were reviewed and graded for emphysematous heterogeneity (from isolated areas to diffuse distribution), extent of maximally perfused lung, and lobar predominance (upper-lobe vs lower-lobe asymmetry). These findings were correlated with clinical outcome on the basis of pulmonary function, arterial blood gas levels, and exercise test results before and 6 months after surgery. RESULTS: Among the 96 patients who survived surgery, there was an average improvement of 47% in the forced expiratory volume in 1 second (FEV1), of 20% in arterial oxygen tension, and of 20% in the 6-minute walking distance. Scintigraphic markers correlated best with FEV1 improvement. The strongest scintigraphic predictor of increase in FEV1 was upper-lobe predominance (r = .38, P < .001), which was followed by heterogeneity (r = .31, P = .002). The seven patients who died had a significantly lower percentage of maximally perfused lung than the survivors (25% vs 34%, P = .004). CONCLUSION: Perfusion scintigraphy can provide modest prognostic information in patients who undergo evaluation for lung volume reduction surgery.

Osteoporosis: diagnosis with lateral and posteroanterior dual x-ray absorptiometry compared with quantitative CT.

PURPOSE: To compare the diagnostic sensitivity of posteroanterior and lateral dual x-ray absorptiometry (PA-DXA, L-DXA, respectively) and quantitative computed tomography (CT). MATERIALS AND METHODS: Among 108 women undergoing lumbar spine bone mineral density assessment, 66 were healthy (mean age, 52.9 years +/- 1.2 [standard error of mean]) and 42 had osteoporosis (mean age, 66.9 years +/- 1.2). RESULTS: Although both L-DXA and PA-DXA correlated well with quantitative CT (r = .73 and .72, respectively; P < .0001), L-DXA correlated better than PA-DXA with age (r = -.69 and -.50, respectively; P < .0001). Women with osteoporosis showed higher bone loss with quantitative CT (1.33% per year) and L-DXA (0.3% per year) than with PA-DXA (0.07% per year). Logistic regression analysis indicated that quantitative CT and L-DXA but not PA-DXA are significant predictors of osteoporotic fractures. Receiver-operating-characteristic curve analyses showed L-DXA to have a sensitivity and specificity closer to those of quantitative CT than did PA-DXA. CONCLUSION: Performance of L-DXA helped discriminate better than PA-DXA between healthy subjects and those with osteoporosis.

Painful transient tibial edema.

PURPOSE: To report four cases of leg pain resembling transient bone marrow edema (TBME). MATERIALS AND METHODS: Four women aged 51-71 years had lower leg pain that regressed over 3-13 months. All patients underwent physical examination, clinical testing, radiography, scintigraphy, and magnetic resonance (MR) imaging. One patient underwent computed tomography; two underwent biopsy. RESULTS: All patients had tenderness at physical examination, and one had erythema and mild swelling over part of the leg. No laboratory results suggested systemic illness or infection. All had normal radiographs and abnormal bone scans, with increased radiopharmaceutical uptake in the tibial diaphyses. MR imaging showed decreased signal intensity with T1-weighting and increased signal intensity with inversion recovery. There were also signal intensity changes consistent with edema in the surrounding soft tissues. Biopsies showed focal marrow fibrosis and new bone formation with foci of devitalized bone. CONCLUSION: These cases resemble TBME but are unusual in their distribution. Whether they represent a previously undescribed clinical syndrome or a variant of TBME remains to be clarified.

Psychological factors in silent myocardial ischemia.

To determine whether psychological factors differentiate patients with silent versus symptomatic myocardial ischemia, a battery of psychometric tests was administered to 68 patients with positive thallium stress tests. Compared with patients who became symptomatic (n = 25), patients with silent ischemia on the treadmill (n = 24) were less often aware of cardiac and other bodily sensations (p less than 0.005) and were less avoidant of harm or pain in general (p less than 0.05). They did not differ on variables associated with symptom reporting biases. To clarify the relationship between ischemia and symptom reporting, symptomatic patients were subgrouped on the basis of anginal pain latency. Psychologically, the patients with silent ischemia were most similar to patients with the longest pain latencies and most different from those who reported angina before the onset of ST depression. The psychological profile of patients with silent ischemia during exercise testing is consistent with a reduced sensitivity to pain and other bodily sensations.

The CT appearance of the giant left atrium.

The Giant Left Atrium (GLA) is a well-known, albeit rare, complication of mitral valve disease. Although traditionally diagnosed by chest X-ray or echocardiography (1, 2), when the left atrium achieves massive proportions, these modalities may be difficult to interpret or even misleading. We report, not only the first description of this entity using computer tomography (CT), but also one of the largest left atria described in the literature. We feel that CT may be reliable when making this diagnosis as well as useful in evaluation of those patients in whom the symptoms suggest some of the complications of this disease.

Electrocardiographic diagnosis of remote posterior wall myocardial infarction using unipolar posterior lead V9.

The accuracy of four electrocardiographic criteria for diagnosing remote posterior myocardial infarction was assessed prospectively in 369 patients undergoing exercise treadmill testing with thallium scintigraphy. Criteria included the following: 1) R-wave width greater than or equal to 0.04 s and R-wave greater than or equal to S-wave in V1; 2) R-wave greater than or equal to S-wave in V2; 3) T-wave voltage in V2 minus V6 greater than or equal to 0.38 mV (T-wave index); 4) Q-wave greater than or equal to 0.04 s in left paraspinal lead V9. Twenty-seven patients (7.3 percent) met thallium criteria for posterior myocardial infarction, defined as a persistent perfusion defect in the posterobase of the left ventricle. Sensitivities for the four criteria ranged from 4 to 56 percent, and specificities ranged from 64 to 99 percent. Posterior paraspinal lead V9 provided the best overall predictive accuracy (94 percent), positive predictive value (58 percent), and ability to differentiate patients with and without posterior myocardial infarction of any single criterion (p less than .0001). Combining the T-wave index with lead V9 further enhanced the diagnostic yield: the sensitivity for detecting posterior infarction by at least one of these criteria was 78 percent, and when both criteria were positive, specificity was 98.5 percent. It is concluded that a single, unipolar posterior lead in the V9 position is superior to standard 12-lead electrocardiographic criteria in diagnosing remote posterior myocardial infarction, and that combining V9 with the T-wave index maximizes the diagnostic yield.

Dual energy radiography (DER): a preliminary comparative study.

Dual energy radiography (DER) has been recently proposed as a new technique for the non invasive measurement of vertebral mineral density. This preliminary study was undertaken to assess the short-term precision of DER and to compare DER to dual photon absorptiometry (DPA) measurements. Three DER measurements were obtained in 19 healthy volunteers (mean age 34.7 +/- 9.3 years) over a 3 week period. In addition, both DER and DPA measurements were obtained in 52 women (mean age 54.3 +/- 12.5 years). The coefficient of variation for the DER measurements was 1.00%. A highly significant correlation (r = 0.94; p less than 0.0001) was found between DPA and DER. Using this curve a conversion factor of -6.8% was calculated to convert DER to DPA values. Both DER and DPA were significantly and similarly correlated with age (r = -0.43, p less than 0.005; r = -0.38, p less than 0.05, respectively). The rates of bone loss, 0.66% per year for DER and 0.57% per year for DPA, were also similar with the two techniques. From these data, it is concluded that DER is a precise new method for vertebral bone mass measurements.

Adhesion-related variceal hemorrhage following sclerosis of esophageal varices.

A 78-year-old woman with portal hypertension had recurrent episodes of lower gastrointestinal hemorrhage two months after bleeding esophageal varices had been successfully treated with endoscopic injection sclerosis. Labeled red blood cell scans and mesenteric angiographic examination allowed a preoperative diagnosis of adhesion-related varices as the cause of bleeding. The problem was successfully treated by dividing the adhesion and resecting the involved small intestine.

Quantitative thallium-201 myocardial imaging in assessing right ventricular pressure in patients with congenital heart defects.

Thallium-201 myocardial scintigraphy was performed in patients with congenital heart defects to determine whether, by quantification of right ventricular isotope uptake, one could assess the degree of right ventricular hypertrophy and so predict the level of right ventricular pressure. A total of 24 patients ranging in age from 7 months to 30 years was studied; 18 were studied before corrective surgery and six after operation. All but three had congenital heart defects which had resulted in pressure and/or volume-overload of the right ventricle. At routine cardiac catheterisation, 20 microCi/kg thallium-201 as thallous chloride was injected through the venous catheter and myocardial images were recorded in anterior and left anterior oblique projections; these were subsequently analysed quantitatively and qualitatively. Insignificant right ventricular thallium-201 counts judged as being less than 1 per cent of the injected dose or less than 0.3 of the left ventricular counts were present in six patients all with right ventricular peak systolic pressure less than 30 mmHg. In the remaining 18 patients there was a good correlation between the right ventricular/left ventricular peak systolic pressure ratio and the right ventricular/left ventricular thallium-201 counts ratio. All patients with right ventricular/left ventricular peak systolic pressure less than 0.5 had right ventricular/left ventricular thallium-201 counts less than 0.4. Qualitative evaluation of right ventricular isotope intensity proved helpful mainly in distinguishing the patients with right ventricular pressures at or above systemic levels. Thus quantitative analysis of myocardial imaging with thallium-201 is of use clinically in patients with congenital heart defects, in assessing the severity of pulmonary stenosis or the presence of pulmonary artery hypertension.

The indeterminate lung scan: its characteristics and its association with pulmonary embolism.

In an unselected series of patients whose only perfusion abnormalities on lung scan matched abnormalities on chest radiograph, the prevalence of pulmonary embolism ranged from 8 to 15%. These estimates depended upon whether only angiographic and autopsy-proven diagnoses were allowed or whether clinical diagnoses were also considered correct. Physical findings and laboratory data, in general, did not contribute to an elucidation of the cause of an indeterminate lung scan. Several radiographic findings with associated perfusion abnormalities (atelectasis alone, multiple infiltrates, bilateral effusions) were not seen in patients with pulmonary embolism. The probability of pulmonary embolism in patients with subsegmental defects alone and matching radiographic findings is about 9%; angiography in these patients would require that nearly two-thirds of the initial patient population undergo this procedure. Patients with larger defects (segmental or lobar) had a higher probability for pulmonary embolism (20--30%) and in these patients angiography is recommended.

Scintigraphy in the followup of pediatric splenic trauma treated without surgery.

Twenty patients with blunt abdominal trauma were diagnosed as having splenic rupture by Tc-99m sulfur colloid scintigraphy. Because of the increased risk of infection in children following splenectomy, surgery was not performed and scintigraphic followup of the injured spleens was carried out. Thirteen patients were scanned at least 2 mo after trauma and the longest followup was 1 yr. Only three spleens showed "scintigraphic healing." The remaining ten showed smaller defects, but in two patients the size of the defect did not change after the 2-mo scan. In no case did the scan defect enlarge. Technetium-99m sulfur colloid scintigraphy offers a convenient and sensitive method of following trauma cases if no surgery is performed. Scintigraphic defects can persist for long periods of time while the patient is asymptomatic.

Pyloroduodenal deformity due to liver malformation associated wtih omphalocele.

While congenital malformed and malpositioned livers are rare, they are relatively common in patients with omphaloceles. A malpositioned, malformed liver causing pyloroduodenal deformity and apparent pyloric obstruction in an infant or child with an omphalocele has not been previously reported. Thee such cases are described in which symptoms of upper gastrointestinal obstruction developed shortly after primary closure of the omphaloceles. Recognition of this condition at the time of primary closure of an omphalocele may allow consideration of additional procedures to prevent postoperative pyloric obstruction.

Visualization of the spleen with a bone-seeking radionuclide in a child with sickle-cell anemia.

99mTc-methylene diphosphonate, a bone-seeking radionuclide, accumulated in the spleen of a 16-year-old boy with sickle-cell anemia even though no splenic calcification was visible. This may be explained by the presence of microscopic calcium deposits in the spleen, which form at an early age in this disease. Bone-seeking radionuclides may accumulate in regions of recent splenic infarction, as has been demonstrated in cerebral and myocardial infarction. Such radionuclides may be the only means of demonstrating the spleen in such patients.

Improved brain scan specificity utilizing 99mTc-pertechnetate and 99mTc(Sn)-diphosphonate.

Each of 36 patients was studied with two separate brain scans performed sequentially after the injection of 20 mCi of 99mTc-pertechnetate or 20 mCi of 99mTc(Sn)-diphosphonate. The resulting scans were qualitatively compared, and lesion-to-nonlesion ratios of activity determined. Diagnoses were established by clinical criteria and were supported in the majority of cases by computerized axial tomography or roentgen angiography or both. Histologic confirmation was available in five cases of tumor and in the single cases of subdural hematoma and cerebral abscess. Of 22 cerebral infarctions, 15 were better demonstrated with 99mTc-(Sn)-diphosphonate than with 99mTc-pertechnetate. Of the seven remaining cases, three were visualized equally well with each agent, and three were better demonstrated with 99mTc-pertechnetate. One was not seen with either agent. Of the 12 tumors, 11 were visualized better with 99mTc-pertechnetate than with 99mTc-(Sn)-diphosphonate while in one case the lesion was seen equally as well with both agents. In no case was a lesion definitely seen with one radiopharmaceutical and not with the other. These results indicate that this dual method is helpful in differentiating gliomas and metastases from cerebral infarctions.