Biomedical subjects
Publications and source records attributed to F L Datz.
The radiolabeling of leukocytes and other cellular elements of the blood has allowed a number of physiologic processes to be investigated. In addition, many commonly performed clinical nuclear medicine procedures utilize these techniques. The following is a review of the labeling technique and of the utility of radiolabeled leukocytes.
We have noted that the presence of left ventricular anterior/apical aneurysm on contrast ventriculography or echocardiography correlates well with the finding of failure of convergence of the left ventricular walls toward the apex on single photon emission computed tomography (SPECT) thallium-201 images. To assess this observation, we analyzed the SPECT thallium scans of 74 sequential patients who had SPECT thallium scintigraphy and contrast ventriculography and/or echocardiography for evaluation of coronary artery disease. Immediate post-stress and 4-hr redistribution thallium-201 SPECT images, obtained following i.v. administration of 2 mCi of thallium-201, were reconstructed with no attenuation correction using three-dimensional linear and nonlinear filters and displayed in short, vertical-long, and horizontal-long axes. Of the 74 patients, contrast ventriculography and/or echocardiography showed anterior/apical aneurysms in 15 and a posterolateral aneurysm in one. SPECT thallium scans detected 14 of the 16 aneurysms, based on the criterion of failure of convergence of the ventricular walls toward the apex. There were two false-positives. Thus SPECT thallium-201 scintigraphy for the detection of left-ventricular aneurysm in this series had a sensitivity of 94%, a specificity of 97%, and an accuracy of 96%.
Proponents of [99mTc]sulfur colloid for GI bleeding studies argue that, although labeled red blood cells are useful for intermittent bleeding, they are not capable of detecting low bleeding rates. Studies of dogs with experimental GI bleeding have indicated bleeding rates of 0.05 ml/min can be detected with [99mTc]sulfur colloid. Since similar data in the dog model were unavailable for 99mTc-labeled red blood cells, we undertook this study. To simulate lower GI bleeding, catheters were inserted into the bowel lumen. Each dog's blood was labeled with 99mTc using an in vitro technique. Venous blood was then withdrawn and re-infused into the lumen of the bowel using a Harvard pump. Fourteen dogs were studied, ten receiving a bleeding rate from 4.6-0.02 ml/min in the descending colon and four with proximal jejunal bleeds of 0.20-0.02 ml/min. Bleeding rates of 4.6-0.2 ml/min were detected within 10 min in the colon and bleeding rates as low as 0.04 ml/min were seen by 55 min. Slower bleeding rates were not detected. Similar findings were noted for proximal jejunal bleeds. Based on the time of appearance, a minimum volume of approximately 2-3 ml labeled blood was necessary to detect bleeding. We conclude that 99mTc-labeled RBCs are sensitive for low bleeding rates in the dog model. The rates are comparable to those described for [99mTc]sulfur colloid in this experimental setting. The time of appearance of activity is related to the bleeding rate.
This study was undertaken to determine if men and women have similar rates of gastric emptying. Fifteen normal weight male subjects aged 20-53 yr (mean 30 yr) and 15 normal weight female subjects aged 20-45 yr (mean 32 yr) were studied. Each subject ingested an identical 300-g meal consisting of 150 g of beef stew and 150 g of orange juice. Technetium-99m-(99mTc) labeled liver pate was used as the radioactive marker for the solid phase; indium-111 DTPA [( 111In]DTPA) was the liquid marker. A scintillation camera and computer was used to measure the rate of emptying of the solid and liquid phases. Correction for radionuclide depth, decay, and crosstalk was performed. The half-emptying time for men was: solids 59.8 +/- 3.7 min, liquids 30.3 +/- 2.3 min, and for women was: solids 92.4 +/- 7.5 min, liquids 53.8 +/- 4.9 min. These differences were statistically significant (solids, p = 0.00097; liquids, p = 0.00038). We conclude that women empty both solids and liquids from their stomachs more slowly than men. Possible mechanisms for the difference in gastric emptying rates between men and women are discussed.
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Stress fractures are a common injury in long-distance runners, and typically involve the lower extremities. Although relatively rare, pubic ramus stress fractures also occur, primarily in female runners. Bone imaging visualized a pubic stress fracture and a tibial stress fracture in a female long-distance runner with groin pain. Pubic stress fractures should be considered in female runners who present with groin pain. Radionuclide bone imaging is useful in diagnosing these lesions.
Radiolabeled blood cells are widely used for both clinical and research studies. In vitro and in vivo studies have shown the tagging process does not significantly affect function. The labeling techniques and clinical uses of labeled leukocytes and platelets are reviewed.
To determine the frequency and clinical significance of indium-111 labeled leukocyte activity in the gastrointestinal (GI) tract of patients with fever of unknown origin, we reviewed 312 leukocyte studies involving 271 patients. Radionuclide activity was noted in the bowel in 59 cases. Of these, only 27 were due to the infection or inflammatory disease that caused the patient's fever. The 32 false-positive results were due primarily to swallowed leukocytes or bleeding. In two cases, no explanation was found for the activity in the GI tract. We conclude that bowel activity on In-111 labeled leukocyte scans in patients with fever of unknown origin often does not correlate with the true cause of the patient's fever.
The 111In-labeled leukocyte scan is a sensitive and specific technique for the detection and localization of abscesses. However, in reviewing an unselected series of 249 scans, six (2.3%) were false-positive cases in which leukocyte uptake by tumor mimicked an abscess. This represented 12% (6/51) with known tumor at the time of imaging. Five of the cases were primary or metastatic tumors to the soft tissues; the sixth was a skeletal metastasis. The intensity of tumor activity has been characterized as mild in the few cases of leukocyte uptake reported in the literature, suggesting that the degree of uptake is helpful in distinguishing tumor from abscess. In this study, however, variable degrees of tumor-associated activity were seen ranging from mild to very intense. These findings indicate that tumor accumulates labeled leukocytes more frequently than has been previously appreciated, that primary and metastatic neoplasms involving both the soft tissues and skeleton are involved, and that the intensity of uptake is not a reliable criterion to distinguish tumor from abscess.
This study was undertaken to determine the effect of chronicity of infection on the sensitivity of In-111-labeled leukocyte scanning. A total of 332 scans on 290 patients were reviewed retrospectively. The diagnosis of infection was based on culture results and other laboratory data, autopsy findings, radiographic studies, and clinical course. Duration of infection at the time of scanning was determined by the date of onset of fever and symptoms, elevation of white cell count, positive cultures, and abnormal findings on radiographic studies. Sensitivity of leukocyte scanning was 90% for 69 patients who had infections for 0-14 days and 86% for 86 who had infections for 15 days or longer. This difference is not statistically significant.
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Indium-111-labeled leukocyte scanning is a highly sensitive and specific method of detecting abscesses. This report describes a patient with polycystic kidneys and a single infected cyst. Ultrasound could not determine which cyst was infected, but the infected cyst could be localized by [111In]leukocyte imaging in conjunction with a [99mTc]DMSA renal scan. The two radionuclide studies were used to identify an infected renal cyst and direct ultrasound guided aspiration.
Brain metastases are rare in well-differentiated thyroid carcinoma but when present they can lead to the patient's death. Iodine-131 therapy for intracerebral thyroid carcinoma metastases causes radiation-induced acute cerebral edema that can lead to CNS complications and even death. We present a case in which a patient with intracerebral 131I uptake developed seizures, slurred speech, and muscle weakness 12 hr following 131I therapy. The patient's CT scan, post-therapy, confirmed an intracranial metastasis with a significant amount of surrounding edema. Radiotherapists, when using external beam radiation to treat intracerebral metastases, commonly place these patients on steroids, glycerol, or mannitol prior to instituting therapy, to prevent complications from radiation-induced cerebral edema. This technique could be applied to 131I therapy of intracranial thyroid carcinoma metastases as well.
Dual isotope gastric emptying studies were performed on 16 morbidly obese patients before and after gastroplasty to determine the effect of this surgery on the rate of emptying. The solid and liquid phases of gastric emptying were compared with a normal control group. In the 900-g and 50-g meals there was a significant difference in the mean half emptying time between solid and liquid phases of emptying (p less than 0.05). Pre-operatively, the 900-g meal half emptying times of both solids and liquids and the 50-g liquid phase meal did not differ significantly between obese patients and the control group. However, in the solid phase of the 50-g meal obese patients differed significantly from a control group (p = 0.007). Three months after gastroplasty, gastric emptying of 50-g meals from the total stomach was not significantly changed from the pre-operative 50-g meal values in ten of 12 patients (p less than 0.05) and no change in total stomach emptying times were seen at 12 mo compared to the 3-mo study (p less than 0.05). Emptying of the pouch alone for both solids and liquids was significantly faster than the pre-operative and postoperative total stomach studies. Gastric emptying in the obese is normal with large meals, but is delayed in small meals. In most patients, gastroplasty does not result in slower emptying of meals.
Although 111In-labeled leukocytes have been shown to be a useful technique for detecting infection, it has been postulated that antibiotic therapy may reduce the sensitivity of the leukocyte scan. Many patients with suspected bacterial infections are placed on antibiotics before a definite site of infection has been identified. Three hundred twelve leukocyte scans on 271 patients were retrospectively reviewed and classified as positive or negative, and as to whether or not they were being treated with antibiotics at the time the leukocyte scan was performed. The overall sensitivity, considering all 312 studies, was 90%. One hundred sixty-nine patient studies were on patients receiving antibiotics; 143 studies were on patients not on antibiotics. The sensitivity of the leukocyte scan was 88.7% in patients on antibiotic therapy; it was 92.1% in those who were not receiving antibiotics. The differences in sensitivity between the two groups were not significantly different (p less than 0.05). We conclude that antibiotic therapy does not affect the sensitivity of the 111In-labeled leukocyte scan.
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Bone marrow aspiration and biopsy are excellent techniques for evaluating bone marrow, but this evaluation is limited to a small part of the total blood-forming organ. With the introduction of radionuclide bone marrow imaging, a simple technique became available that overcomes marrow sampling errors by giving a total body view of functioning marrow. Furthermore, the procedure is noninvasive and provides an atraumatic method for evaluating a number of clinical problems including a discrepancy between bone marrow histology and clinical status (possible marrow sampling error), the determination of amount of active marrow after radiation and chemotherapy when further therapy is being considered, detection of sites of extramedullary hematopoiesis, location of the optimal sites for bone marrow biopsy, the diagnosis and staging of diffuse hematologic disorders, detection of metastases, the diagnosis of bone marrow infarcts in hemolytic anemias, and detecting avascular necrosis of the femoral heads. There are two major classes of bone marrow agents: (1) those that are incorporated into the erythroid precursors such as radioiron and (2) colloids that are taken up by the reticuloendothelial system (RES). Indium-111 chloride was originally considered to be an erythropoietic agent but appears to share some properties of RES labels. The best label to use is dependent on the disease being evaluated.