Ernest W. Fordham

Normal thymic uptake of FDG on PET imaging

Assessment and characterization of the thymus by various imaging methods have been extensively described. The authors report increased uptake of 2-(18)Fluoro-2-deoxy-D-glucose (FDG) in the normal thymus gland of patients between the ages of 2 and 13 years. Most of these patients had PET scans for various oncologic conditions and had no clinical problems referable to the thymus gland. This uptake assumes an important role when evaluating mediastinal uptake in whole-body PET scans in pediatric oncology patients to avoid false-positive interpretation.

Gallium-67 imaging in the management of Hodgkin's disease and other malignant lymphomas

Gallium-67 imaging is useful in the management of patients with malignant lymphoma, despite its obvious limitations. Data currently in the literature regarding the detectability of sites of lymphoma by 67Ga imaging should be regarded as representing the minimum that can be expected from the method, since all reported series are based on outmoded imaging techniques. The detectability of disease sites appears to vary with tumor histology and anatomic location. Gallium-67 imaging is most useful in following patients after treatment. However, it may justifiably play an important role in the initial staging of lymphoma if the prior probability of disease in the abdomen is low. Lymphoma in abdominal lymph node sites is at least as detectable by 67Ga imaging as by lymphangiography.

Bone scanning in pregnant patients with breast carcinoma.

Radionuclide scanning is usually contraindicated in pregnancy because of the danger of fetal radiation exposure. Radionuclide bone scanning with Tc–99m MDP is a sensitive indicator of early osseous metastases in breast cancer. Three cases of breast cancer during pregnancy are reported; modified bone scanning was utilized for staging and decision analysis. Modifications of bone scanning techniques to minimize fetal radiation exposure and fetal dosimetry calculations are described.

Radionuclide imaging of osseous trauma

Radionuclide imaging in osseous trauma is now possible with the availability of low-radiation-dose bone-localizing agents. Bone trauma results in increased uptake of activity at the traumatic site by the 3rd day. Maximum uptake occurs at 3 to 5 weeks and may resolve over a variable time. Increased uptake at the site of a fracture may persist for many years. Osseous imaging has proved useful in neurologic problems, circulatory disease, aseptic necrosis, direct bone trauma, stress, iatrogenic trauma, and radiation injury. The agents of choice currently are 18 F and the bone-localizing compounds of 99m Tc.

Indium-111 DTPA flow study to evaluate surgically implanted drug pump delivery system.

The authors describe a radionuclide technique for evaluating intrathecal and intraventricular infusions by surgically implanted drug pump delivery systems. Sixteen patients underwent flow studies, performed by injecting 500 μCi of indium-111 DTPA into the pumps. Early and delayed images were obtained. These studies enabled distinction among functioning pumps, nonfunctioning pumps, and obstructed or occluded catheters. We conclude that indium-111 DTPA flow studies provide an excellent way to assess these drug pump delivery systems.

Quantitative sacroiliac scintigraphy. The effect of method of selection of region of interest

Various authors have advocated quantitative methods of evaluating bone scintigrams to detect sacroiliitis, while others have not found them useful. Many explanations for this disagreement have been offered, including differences in the method of case selection, ethnicity, gender, and previous drug therapy. It would appear that one of the most important impediments to consistent results is the variability of selecting sacroiliac (SI) joint and reference regions of interest (ROIs). The effect of ROI selection would seem particularly important because of the normal variability of radioactivity within the reference regions that have been used (sacrum, spine, iliac wing) and the inhomogeneity of activity in the SI joints. We have investigated the effect of ROI selection, using five different methods representative of, though not necessarily identical to, those found in the literature. Each method produced unique mean indices that were different for patients with ankylosing spondylitis (AS) and controls. The method of Ayres (19) proved superior (largest mean difference, smallest variance), but none worked well as a diagnostic tool because of substantial overlap of the distributions of indices of patient and control groups. We conclude that ROI selection is important in determining results, and quantitative scintigraphic methods in general are not effective tools for diagnosing AS. Among the possible factors limiting success, difficulty in selecting a stable reference area seems of particular importance.

'False-positive' uptake of FDG in a hepatic adenoma

Positron emission tomography using F-18 FDG is becoming a very useful test in the evaluation of many tumors because of its high sensitivity and specificity. However, on rare occasions, it may be difficult to differentiate a neoplasm from a benign lesion. This article describes increased metabolic activity in a hepatic mass found on a routine follow-up CT examination of the abdomen in a 41-year-old woman with a history of bilateral breast carcinoma. Based on an elevated differential uptake ratio of 4.2, the lesion was thought to be consistent with a metastatic tumor. The hepatic mass was removed surgically and proved to be a hepatic adenoma.

The relationship of computed tomography, gray-scale ultrasonography and radionuclide imaging in the evaluation of hepatic masses.

Hepatic scintigraphy, gray-scale ultrasonography, and computed tomography have proven to be useful in the initial detection and evaluation of hepatic masses. These studies appear to be complimentary since each provides information not available from the others. Hepatic scintigraphy is currently the method of choice for the initial evaluation of the liver for mass lesions as it is easily performed, relatively inexpensive, and affords detectability of intrahepatic mass lesions at least as great as that of ultrasonography or computed tomography. When a definite or suspected abnormality is seen by hepatic scintigraphy, computed tomography or ultrasonography may be helpful in providing better anatomic definition or clarification of the nature of the abnormality. The choice between these latter two modalities depends on the type of scanning equipment available and the observers experience with each method.

Bone Scintigram in Cardiac Amyloidosis: A Case Report

Intense, diffuse localization of Tc-99m-pyrophosphate was demonstrated in the right and left ventricles of a patient with biopsy-proved amyloidosis and severe congestive heart failure. This finding is strong presumptive evidence of myocardial infiltration by amyloid in the presence of biopsy-proven amyloidosis elsewhere in the body.

False-positive hepatic blood pool SPECT study for hepatic hemangioma

Radionuclide hepatic blood pool scintigraphy is an extremely sensitive and highly specific test in diagnosing cavernous hemangioma of the liver. The authors report a false-positive hepatic blood pool scintigram for hepatic hemangioma in a patient with liver metastasis from adenocarcinoma of colon.