Philip O. Alderson

Skeletal uptake of 99mTc-diphosphonate in relation to local bone blood flow.

The right/left ratios of tibial uptake of 99mTc-diphosphonate (EHDP) and relative blood flow (based on microsphere distribution) were determined in control rats and rats with a ligated right femoral artery or a healing right tibial fracture. Correlation between 99mTc-EHDP uptake and relative blood flow was highly significant (r=0.917; P less than 0.0001) for relative flow ratios less than 1.7. When the ratio was greater than 1.7, there was little further increase in 99mTc-EHDP uptake. Ligation of the femoral artery in rats with healing fractures resulted in a more marked reduction of blood flow than of 99mTc-EHDP uptake. These results suggest that regional bone blood flow is a major determinant of 99mTc-EHDP uptake, though changes in regional tracer extraction efficiency are also important.

The role of 133Xe ventilation studies in the scintigraphic detection of pulmonary embolism.

The angiographic, scintigraphic, and clinical data of 40 patients were reviewed in order to define the role of 133Xe ventilation studies in the radionuclide detection of pulmonary embolism. Two independent observers interpreted the perfusion images, and several weeks later reinterpreted them in conjunction with 133Xe ventilation studies. Overall diagnostic accuracy was significantly improved (p less than 0.05) when the xenon studies were included. The combined studies were slightly more sensitive and significantly more specific (p less than 0.05) for pulmonary embolism than the perfusion images alone.

Pulmonary deposition of aerosols in children with cystic fibrosis

The efficiency of delivery of an aerosol to 22 children with cystic fibrosis, aged 8 months to 17 years, was investigated with the use of a standard ultrasonic nebulizer. The study was designed to simulate clinical conditions as closely as possible. Retention of the aerosol was monitored with a scintillation camera interfaced to a small digital computer. The children also had ventilation studies with xenon-133, which allowed comparison of the distribution of aerosol with regional ventilation. The aerosol was visualized within the lungs of all 22 patients. Between 0.8 and 6.5 per cent of the initial activity was deposited in the lungs, representing an average of 0.27 ml. per therapy session or 0.013 ml. per kilogram of body weight. There was a positive correlation (r=0.89; p

Interpretation of Indeterminate Lung Scintigrams

Lung scintigrams and pulmonary angiograms of 111 patients with suspected pulmonary embolism who had matching perfusion defects and radiographic abnormalities (infiltrate, atelectasis, or effusion) were reviewed. In 14 patients perfusion defects were substantially smaller than the corresponding radiographic opacity; only 1 (7%) had pulmonary embolism. In 77 the opacities and perfusion defects were of similar size; the abnormality was due to embolism in 20 (26%). In 18 patients perfusion defects were substantially larger than the radiographic opacities and were not associated with matching ventilation abnormalities; of these, 16 (89%) had pulmonary embolism. Evaluation of the relative size of perfusion defects and radiographic abnormalities occurring in the same region improves the ability of lung scintigrams to predict pulmonary emboli.

Gallium-67 imaging in abdominal disease.

Gallium-67 imaging is useful for detecting sites of intra-abdominal inflammation, including subphrenic abscesses, postoperative infection, pyelonephritis or perinephric abscesses, and peritonitis. Positive images may be obtained within several hours of injection, but are more reliable at 24 hr. The results may be used to guide ultrasound or computed tomography studies, which give a detailed anatomic picture of the abscess. Gallium-67 imaging has also been used to detect abdominal neoplasms, but results are less impressive. Abdominal lymphoma is detected in just over 50% of sites. Gastrointestinal, renal, and gynecologic neoplasms are detected even less frequently. However, 67Ga is useful for detecting recurrence of 67Ga-avid neoplasms, and has been reliable in detecting hepatomas and nodal spread of seminoma. When used selectively in patients with neoplastic disease and suspected abscesses, 67Ga is an effective method for diagnosing abdominal disease.

Scintigraphic evaluation of liver and spleen injury.

The liver and spleen may be damaged by blunt or penetrating trauma to the upper abdomen. Scintigraphic studies have proved quite useful in detecting the presence and delineating the extent of these injuries. In addition to the conventional anterior, lateral, and posterior views, special angulated and oblique views are sometimes needed. These studies provide the information that often is needed when surgical exploration is contemplated. Contrast angiography is used in equivocal situations. latrogenic changes caused by radiation or surgery of the liver may also be demonstrated and followed with scintigraphic studies. Examples of all these situations are included in this review.

Correlation between computerized transaxial tomography and radionuclide cistemography in dementia

A study of the findings on cistemograms and computerized transaxial tomography (CTT) of 44 patients showed good correlation between the two tests. Patients with a cistemographic pattern of communicating hydrocephalus tended to show more severe degrees of lateral ventricular dilatation, with involvement of the third and fourth ventricles and relative sparing of the cerebral sulci. Patients with a cistemographic pattern of cerebral atrophy showed lesser degrees of lateral ventricular dilatation and more severe degrees of dilatation of the cerebral sulci. The statistical significance of the individual CTT findings in these patients is presented, and a scheme for interpretation is proposed. The study shows that CTT can replace pneumoencephalography in evaluating patients with dementia, while cisternography contributes complementary information.

Detection of Obstructive Pulmonary Disease

A double-blind evaluation of the chest radiographs and ventilation-perfusion scans of 160 patients was performed to assess their relative sensitivity in detecting obstructive airway disease. In 76 the initial scan diagnosis was obstructive pulmonary disease; 35 of these showed no radiographic evidence of COPD. The abnormalities in these 35 were significantly milder than in the 41 others. Perfusion scans were normal in 7 patients with mild disease and normal radiographs. Regional ventilation studies are helpful in evaluating cases of mild to moderate airway obstruction which would be misdiagnosed by radiographs or perfusion scans alone.

Comparison of computerized tomography and radionuclide imaging in "stroke".

Forty patients were studied by computerized tomography and by radionuclide brain imaging. The final diagnosis was infarction in 29 patients, intracerebral hematoma in seven, acute SAH in one, and old cerebrovascular accidents in three. CT was far superior to RN in detecting intracerebral hematomas and distinguishing them from cerebral infarction. The results of CT and RN tests were comparable regarding the percentage of abnormalities. However, the results in the same patients were not identical in 55% of the cases, indicating a complementary role for the two tests. There was no relationship between the frequency of abnormalities on CT and the time lapse afte the onset of cerebral infarction. RN uptake was not seen in patients with old cerebrovascular accidents.

Computerized cranial tomography and radionuclide imaging in the detection of intracranial mass lesions

Computerized cranial tomography (CCT) and radionuclide imaging (RI) of the brain are both accurate techniques for detecting intracranial mass lesions. CCT is superior in detecting low-grade gliomas, cystic lesions, parasellar tumors, and brain stem lesions. Overall, CCT detection rates are slightly higher than those with RI, but the use of iodinated contrast media with CCT increases the risk of this examination. There is a significant difference in the generally binary (positive/negative) type of information offered by RI and the more specific information offered by CCT about the pathologic nature of a lesion and its precise location. In the evaluation of patients with suspected intracranial mass lesions, CCT is generally the preferable initial diagnostic test. However, RI may still serve as a satisfactory screening examination in certain well-defined clinical situations.