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Single-photon emission computed tomography (SPECT) and hybrid SPECT/computed tomography (SPECT/CT) cameras have emerged as a dominant technology providing invaluable tools in the diagnosis, staging, therapy planning, and treatment monitoring of multiple cancers over the past decade. In the same way that positron emission tomography (PET) benefited from the addition of CT, functional SPECT and anatomic CT data obtained as a single study have shown improvements in diagnostic imaging sensitivity and specificity by improving lesion conspicuity, reducing false positives, and clarifying indeterminate lesions. Furthermore, the anatomic imaging better localizes the functional data, which can be critical in surgical and therapy planning. As more disease-specific imaging agents become available, the role of SPECT/CT in the new paradigms of molecular imaging for personalized medicine will expand. Established and emerging uses of SPECT/CT in a wide variety of oncologic diseases, as well as radiation exposure issues, are reviewed.

Sentinel lymph node (SLN) biopsy is revolutionizing the surgical management of primary malignant melanoma. It allows accurate nodal staging which targets patients who may benefit from regional lymphadenectomy and systemic therapy. This is a retrospective review of patients treated at Emory University for stage I and II malignant melanoma with gamma probe-guided SLN biopsy from 1/1/94 to 6/30/98. Three hundred sixty patients (males 228, females 132) were identified. Primary melanoma sites included: head and neck 58, trunk 148, and extremities 154 (upper 71, lower 83). Primary tumor staging was T19, T2134, T3153, and T464. SLNs were successfully identified in 99.7 per cent of patients and 98.9 per cent of nodal basins mapped. In 275 (76.6%) cases a single draining nodal basin was identified. In 84 (23.3%) cases there were multiple draining nodal basins. Positive SLNs were identified in 63 patients (17.5%). SLN positivity by tumor staging was T10 per cent, T29.0 per cent, T322.2 per cent, and T426.6 per cent. The overall recurrence rate was 11.9 per cent. Recurrences by SLN status were SLN+, 27 per cent, and SLN-, 8.8 per cent. Regional recurrence occurred in 7 (2.4%) of the 297 with negative SLN biopsies and 7 (11.1%) of the 63 with positive SLN biopsies. Dynamic lymphoscintigraphy and gamma probe-guided SLN localization was successful in more than 98 per cent of cases. Patients with negative SLN biopsies have a low risk of recurrence.

Sodium 18F-fluoride (NaF) is a diagnostic marker for new bone formation in bone scintigraphy that was approved by US FDA in 1972 but discontinued in 1984. We report a case of a US naval officer who spent time living and working in an oceanic lab, 205 feet below the surface. Plain skeletal films of femurs 4 years later demonstrate bilateral bone infarcts. Corresponding sodium 18F-fluoride bone scintigraphy demonstrates low-normal to decreased tracer activity. This rectilinear scan image is of historical interest. Other bone scintigraphic radiotracers used in the past and present will be briefly discussed.

One hundred consecutive patients with findings suggestive of resectable bronchogenic carcinoma were studied prospectively to determine if routine liver, brain, and bone scans (multiorgan scans) detected metastases which were not suggested by a history, physical examination, and serum chemistries. Multiorgan scans were compared with clinical evaluations in 52 patients found to have operable bronchogenic carcinoma. There was a discordance between scans and clinical evaluations in 25/153 scans (16 per cent). Two of the 22 negative scans in patients with abnormal clinical findings were false negative. Sixteen of the 17 positive scans in patients with normal clinical findings were false positive. One of the 131 scans done in patients with no evidence of metastases on clinical evaluation was true positive. These data indicate that the routine use of multiorgan scans in the initial staging of potentially resectable bronchogenic carcinoma is not justified.

Full-thickness right ventricular latissimus dorsi dynamic cardiomyoplasty with the Medtronic Cardiomyostimulator (Medtronic, Inc., Minneapolis, Minn.) was performed in a chronic canine model. In one group (n = 2) the latissimus dorsi was electrically preconditioned before cardiomyoplasty. In a second group (n = 3) cardiomyoplasty was performed and the muscle was progressively stimulated, with conditioning accomplished while the latissimus dorsi was functioning on the ventricle. The contribution of the stimulated latissimus dorsi to global ventricular function was assessed, and the effects of varying muscle stimulation parameters on latissimus dorsi function and hemodynamics were examined. Right ventricular systolic pressure increased 8%, from 23.2 ± 0.95 to 25.1 ± 1.5 mm Hg. The rate of pressure rise increased 37% from 226 ± 13 to 309 ± 12 mm Hg/sec. Right ventricular ejection fraction was measured in two dogs and increased 29% with latissimus dorsi stimulation, from 51.5% ± 13.5% to 66.5% ± 14.5%. Although the sample size was small, there was no difference observed between the preconditioned and nonpreconditioned groups. Right ventricular systolic pressure, rate of pressure rise, and percent latissimus dorsi fiber shortening increased as voltage and burst frequency of the muscle stimulus increased, whereas increasing the burst duration had little effect in two dogs so studied. Latissimus dorsi dynamic cardiomyoplasty can function as a partial myocardial replacement in a chronic canine model, apparently without preconditioning of the muscle. The degree of cardiac assist obtained with cardiomyoplasty appears to be influenced by the voltage and frequency of the stimulus applied to the muscle. Although it is unclear whether these results can be extrapolated to the left ventricle, this technique may find application in the treatment of ventricular aneurysm or ventricular tumor.

This article reviews the neuroimaging of AD, including CT, magnetic resonance (MR), positron emission tomography (PET), and single photo emission CT (SPECT), as well as some of the newer techniques of MR spectroscopy and functional MR imaging. Functional studies, such as PET and SPECT, map cerebral metabolism or perfusion and improve the specificity of dementia diagnosis. In addition, functional imaging may demonstrate metabolic or perfusion abnormalities that precede morphologic changes on MR or CT. Recent developments suggest that a combination of functional and anatomical studies may best differentiate AD from non-AD dementias and aging.

When the solid fraction of a standardized meal is labeled with technetium 99m-sulfur colloid-labeled chicken liver and fed to human subjects, linear regions of decreased radioactivity that have the appearance of a band are identified on the scintillation camera images of the stomach. The band is not a peristaltic contraction because it persists in individual subjects after 4 h of imaging. The band has also been identified in the dog, pig, and monkey. It is transverse and midgastric in location. William Beaumont noted a similar band in his observations on Alexis St. Martin in 1833, and a transverse band was noted in autopsy specimens of food-filled human stomachs in 1919. However, the finding has been ignored in current gastrointestinal or radiologic textbooks because the band cannot be identified with conventional barium sulfate meals. The anatomic basis for the band and its role in regulating gastric emptying remain unclear.

Abstract: An experiment was designed to determine whether or not acute pneumococcal pneumonia in dogs is associated with intravascular thrombosis, or with angiographic features distinguishable from pulmonary embolism. In dogs with normal baseline chest radiographs and perfusion scans, pneumonia was produced by transbronchial instillation of type III pneumococcus. After 2 days, perfusion scans demonstrated discrete appropriate defects. In vivo magnification pulmonary arteriography, postmortem pulmonary arteriography, and histologic examination disclosed no evidence of thrombi.

Morton KA, Alazraki NP, Datz FL, Taylor AT, Winge D, Lynch RE. Uptake of cadmiuum-109, a metallothionein-binding radiometal, by tumors in mice as a function of the transformed phenotype. Invest Radiol 1988;23:200–204.

Experiments Were conducted to further evaluate previously observed discrepancies between postembolic perfusion scans and angiograms, and the relationship of these discrepancies to pulmonary vasospasm. Nonresorbable emboli were formed from Ivalon, muscle, or heated autologous clot. Scans and angiograms were compared at 24-hour intervals for two to eight days. During the first two days after embolism, angiographic-scan discrepancies occurred in most dogs, characterized by decreased size of scintigraphically demonstrated perfusion defects at the same times that the angiogram showed stable or even progressive obstruction. This discordant behavior of scan and angiogram is thought to reflect subsidence of postembolic vasospasm. In the 17 experimental dogs, 13 showed evidence of vasospasm, and four did not. In those that developed spasm, direct angiographic evidence of such spasm was present in all but one, manifest as diffuse constriction of small arteries and diminished parenchymal stain in vascular beds that were not directly obstructed mechanically. Although spasm diminished rapidly during the first 6 hours, there was continued and appreciable further resolution for over 48 hours in some dogs. This study reconfirms the frequent existence of vasospasm in three different embolic models, and indicates subsidence of spasm over a much longer time frame than was formerly supposed. Regression of spasm over an interval of several days suggests that perfusion scans should be performed clinically as soon as possible after a suspected embolic episode, prior to subsidence of spasm, in order to exploit the added sensitivity provided by spasm.

To differentiate upper from lower-tract urinary infections, 73 patients were imaged with 67Ga citrate. Renal uptake of the radioisotope occurred in pyelonephritis (documented in 47 patients by ureteral catheterization, bladder washout, or histology) with an accuracy of 86 per cent. There were 15 per cent false-positives and 13 per cent false-negatives. 67Ga may prove to be a clinically valuable test in the diagnosis of pyelonephritis. Results are promptly available 24 hours after injection, and it is a non-invasive test that can safely be repeated to follow recurrent infections.

99mTc-mercaptoacetyltriglycine (MAG3) is a new renal radiopharmaceutical which has been shown to have biological properties similar to131I-hippurate (OIH) in animals and volunteers.99mTc-MAG3 has now been compared with131I-orthoiodohippurate (OIH) in a group of patients with varying degrees of renal impairment. In all cases, the99mTc-MAG3 images were superior regardless of serum creatinine. Selected examples are illustrated including scans and renogram curves in a normal volunteer, transplant patients with creatinines of 9.8 mg/dl and 2.6 mg/dl respectively, and a furosemide study in a patient with questionable obstruction. Our preliminary results suggest that99mTc-MAG3 performs well in patients with impaired renal function and may well provide an acceptable replacement for OIH. A kit formulation has been developed and will soon be undergoing clinical evaluation.

Routine cerebral dynamic scanning in two patients revealed unilateral focal areas of decreased radionuclide activity between the anterior and middle cerebral arteries; the subsequent brain scans were normal. Both patients were shown to have porencephaly by isotope cisternography and computed tomography (CT) scans. When a focal avascular area is noted on cerebral dynamic scanning in the presence of normal static images, the possibility of a porencephalic cyst should be considered.

The size of the liver and spleen was determined by scintiphotography in 214 patients and the results correlated with the physical findings concerning these two organs. False-positive interpretations of liver size and false-negative interpretations of spleen size were very common as determined by physical examination. The findings of a palpable spleen by physical examination correlated to a very high degree with anatomical enlargement of that organ.