Clinical significance of solitary rib lesions in patients with extraskeletal malignancy.

A retrospective review of 2,851 bone scans done at a cancer center over a period of 4 yr revealed 41 patients having a single abnormality in a rib as their first abnormal scintigraphic finding. The scan findings in these cases were correlated with clinical, scintigraphic, and radiographic follow-up to ascertain their etiology and course. Four lesions (9.8%) were due to malignant disease, 16 (39%) were associated with benign fractures demonstrated on x-ray, 11 (27%) were associated with primary or postoperative radiation therapy. The remaining ten patients (24.2%) with normal x-rays and no association with radiation therapy or subsequent development of metastasis were assigned to benign etiology. This experience suggests that solitary rib lesions in cancer patients are uncommon and are most frequently (90%) associated with benign etiology.

Three cases demonstrating the role of gallium scanning in relapsing Hodgkin's disease and non-Hodgkin lymphoma.

Restaging of Hodgkin's disease and non-Hodgkin lymphoma for chemotherapy traditionally requires chest radiograph and abdominal computerized tomogram (CT) for routine follow-up examination. Although gallium scanning has had a poor record in the past, recent studies suggest that improved techniques have given this method high sensitivity. We present three cases in which gallium correctly staged lymphoma that had been missed or misinterpreted by chest radiographs and abdominal CT. Gallium imaging is useful in follow-up of lymphoma patients especially when the CT scan is difficult to interpret.

Brain perfusion SPECT using an annular single crystal camera: initial clinical experience.

The annular single-crystal brain camera (ASPECT) is a digital SPECT system with a single-crystal sodium iodide thallium Nal(Tl) ring detector and collimator system designed to view the patient's head from three angles simultaneously. The ring is rotated concentrically to the detector for three-dimensional reconstruction over a 21.4 cm (diameter) by 10.7 cm (length) field of view. We evaluated the system clinically by imaging a Hoffman brain phantom and seven subjects, of whom two were normal controls, three had previous cerebral infarction and two had dementia. The ASPECT system produced tomographic images of high spatial resolution. In normal subjects, the separation of striata from thalami by the posterior limbs of the internal capsules was much clearer on ASPECT images than on rotating gamma camera images. The high spatial resolution obtained with the ASPECT system translates into superior anatomical representation of the brain compared to the standard rotating gamma camera.

A new Tc-99m-labeled myocardial imaging agent, hexakis(t-butylisonitrile)-technetium(I) [Tc-99m TBI]: initial experience in the human.

The cationic complex Tc-99m hexakis(t-butylisonitrile)technetium(I) (TBI) has been shown to concentrate in the myocardial tissue of several animal species. In the present preliminary study, the biodistribution of this material was examined in four normal subjects and in two patients with coronary artery disease. In three normal humans injected at rest, planar, tomographic, and gated myocardial images of high technical quality were obtained between 1 and 4 hr after injection. In one subject studied both at rest and during maximal exercise, the lung and heart activities were similar, whereas the liver-to-heart activity ratio was 3:1 at 60 min at rest compared with 1.8:1 with maximal exercise. In two patients with coronary artery disease, transient ischemia appeared as a perfusion defect up to 4 hr after injection at maximal exercise, and the image appeared normal when Tc-99m TBI was administered at rest. The images of areas of infarction appeared abnormal after injection at rest and after injection during exercise. Technetium-99m TBI is a promising myocardial imaging agent that may permit high-quality planar, gated, and tomographic imaging of myocardial ischemia and infarction.

Iodine-131-metaiodobenzylguanidine scintigraphy in preoperative and postoperative evaluation of paragangliomas: comparison with CT and MRI.

Iodine-131-metaiodobenzylguanidine (MIBG) scintigraphy, transmission computed tomography and magnetic resonance imaging were used to evaluate 36 patients with clinically suspected functioning paragangliomas. The patients were divided into two groups. In Group 1 (n = 21), studied before surgery, patients mainly had benign adrenal disease. In Group 2 (n = 15), studied after surgery, patients frequently had malignant or extra-adrenal tumors. In Group 1, transmission computed tomography and magnetic resonance imaging were more sensitive (100% for both) than MIBG scintigraphy (82%), which, however, was the most specific (100%). In Group 2, MIBG scintigraphy and magnetic resonance imaging were more sensitive (83% for both) than transmission computed tomography (75%), but MIBG was again the most specific (100%). Thus, all three were complementary modalities for localizing paragangliomas both preoperatively and postoperatively. MIBG imaging is indicated for both groups but it is especially recommended for postsurgical patients with recurrence because the disease is often malignant or extra-adrenal.

Intratumoral administration of 5-[123I]iodo-2'-deoxyuridine in a patient with a brain tumor.

UNLABELLED: We have initiated a study in which patients suspected of having primary gliomas are given a single intracerebral injection of the thymidine analog 5-[123I]iodo-2'-deoxyuridine ([123I]IUdR). The purpose of the study is to determine the biodistribution of the radiopharmaceutical and to calculate dose estimates to the tumor and normal tissues. METHODS: A patient with a cystic glioma was injected with [123I]IUdR. Whole-body scans and brain scans were obtained at various times after injection, and blood, urine and stools were collected and assayed for radioactivity to assess its biodistribution and clearance. RESULTS: Scintigraphic imaging demonstrated that the distribution of radiolabeled IUdR was mainly confined to the tumor (injection site), stomach and bladder. Disappearance from the tumor site and blood clearance were delayed probably due to collection in the cystic lesion. Eighty percent of the injected dose was recovered in the urine. CONCLUSION: The pharmacokinetics of [123I]IUdR locoregionally administered to a human glioma in situ resembled those observed in a rat glioma model where administration of the radiopharmaceutical radiolabeled with the Auger electron emitter 125I was therapeutically effective.

Platelet activation and aggregation after endothelial injury. Assessment with indium-111-labeled platelets and angiography.

Although platelet activation and aggregation after endothelial injury are well documented, the time course of platelet deposition and the relationship between platelet aggregation and the release of vasoactive products have not been fully clarified in vivo. To study the effect of platelet vasoactive products, a collateral blood supply was induced by ligating the superficial femoral artery in male New Zealand white rabbits. Two weeks later, endothelial injury to the distal abdominal aorta was produced by cytologic brush or mimicked with a metal coil embolus. Platelet aggregation was assessed with indium-111 (111In)-labeled platelets, and scintigraphy demonstrated significant, progressive platelet deposition up to 3 hours after injury and evidence of residual activity 24 hours later. Angiography showed that the time course of peripheral vasoconstriction matched closely that of platelet deposition, indicating release of vasoactive substances from the aggregating platelets. These pathophysiologic changes secondary to endothelial injury may have significant implications for intravascular interventional procedures.

Embolization of platelets after endothelial injury to the aorta in rabbits. Assessment with 111indium-labeled platelets and angiography.

This study exploits the ability of a collateral arterial network to trap platelet aggregates in order to document the frequency of macroembolization in rabbits after endothelial damage. Two weeks after ligation of the right superficial femoral artery, endothelial injury was induced in the distal aorta; within 3 hours the rabbits were studied using either angiography or 111indium-labeled (111In) platelet scintigraphy. Angiography indicated visible aggregates in the thigh region in eight of 19 and arterial occlusion in three of 19 rabbits. The collateral-dependent thigh also showed more 111In-labeled platelet activity than the contralateral side (P less than .001), whether platelets were injected before or 2 hours after injury. Radioactivity in the limbs of rabbits with no injury was distributed symmetrically. Blood pool volume, assessed with technetium-99m-labeled red blood cells, was the same in both thighs, and could not account for these observations. The findings indicate that platelet activation and aggregation after endothelial injury lead to microembolization much more frequently than it leads to macroaggregate formation and visible artery occlusion.

Nuclear medicine techniques in septic arthritis and osteomyelitis.

Imagers are consulted to confirm the presence of acute osteomyelitis, to evaluate disease activity and chronic osteomyelitis, and to confirm the presence of a sequestrum in active chronic osteomyelitis. Scintigraphy remains the most sensitive and specific modality for the diagnosis of acute osteomyelitis and the evaluation of activity of chronic osteomyelitis. Computed tomography is the best examination for the confirmation of the presence of sequestra. In this article, the authors review the various radionuclide techniques, their applications in the different clinical settings, and the way in which they correlate with other imaging techniques.

Detection of periodontal disease activity with a scintillation camera.

The goal of this study was to assess the ability of a scintillation camera method to detect areas of active bone loss due to periodontitis. Technetium 99m methylene diphosphonate was used as the bone-seeking radiopharmaceutical. Bone-seeking radiopharmaceutical uptake (BSRU) was imaged and quantified in alveolar bone regions of interest with a scintillation camera and a computer. Analysis of the sequential radiographs over six months constituted the basis for determination of sites of active disease. The study was composed of two parts. First, 18 subjects, nine with adult periodontitis and nine controls, were enrolled in a cross-sectional study to determine whether the quantitative scintillation amera methodology detected differences in BSRU in periodontitis vs. periodontally healthy patients. Second, the nine patients with periodontitis were studied longitudinally in order to determine whether the BSRU examination was indicative of bone loss subsequently measured radiographically. In the cross-sectional study, the mean uptake ratio for the periodontitis group was significantly higher than that for the control group (1.63 +/- 0.06 and 1.42 +/- 0.04, respectively, p less than 0.01, t test). From the longitudinal study, the mean patient scintillation image uptake ratios were highly correlated with the mean bone loss determined from serial radiographs (p less than 0.01). The accuracy, sensitivity, and specificity of the quantitative gamma camera method for detecting site(s) of active bone loss within the region of interest were assessed relative to the longitudinal radiographic data. The accuracy, sensitivity, and specificity were 85%, 90%, and 79%, respectively. Alveolar bone scintigraphy with a gamma camera and computer may provide a simple and valid technique for the immediate indication of areas of periodontal disease activity.

Scintigraphy in the evaluation of arthropathy.

Significant progress has been made in radionuclide imaging of bones and joints. This largely is owing to advances in radiopharmaceuticals, particularly the antibodies, and in technology, particularly in the introduction of new computers and multiheaded camera systems resulting in improved imaging. These techniques have applied to the evaluation of articular and para-articular diseases including rheumatoid arthritis, septic arthritis, osteoid osteoma, transient osteoporosis, reflex sympathetic dystrophy, avascular necrosis, and facet joint syndrome. This article reviews scintigraphy in these conditions.

Acute diseases of the scrotum.

Several imaging modalities are available for evaluating the patient with acute scrotal pain. Until recently, scintigraphy was the initial procedure of choice in most patients, as it was the only noninvasive technique for determining integrity of blood flow to the testicle. Ultrasound was valuable when the scintiscan was inconclusive or in the setting of scrotal trauma. With the advent of color Doppler sonography, information about both structure and blood flow can be obtained by means of a single imaging study. If initial promising results with this newer technique are borne out, color Doppler is likely to become the primary diagnostic test in patients with acute scrotal pain. The role of MRI and MRS has yet to be defined.

Bile duct disruption after laparoscopic cholecystectomy.

The reported prevalence of biliary tract disruption following laparoscopic cholecystectomy has ranged from 0% to 7% in early reports. We have reviewed the first 823 laparoscopic cholecystectomies performed at our institution and found 13 symptomatic biliary complications necessitating further therapy (prevalence 1.6%). This finding represents a decrease from the 2.7% prevalence found in our earlier series. The incidence of biliary complications will likely continue to vary depending on patient selection, operator experience, and new developments in laparoscopic technique. Bile duct injury and bile leaks are often difficult to diagnose but must be strongly considered in postoperative patients with abdominal pain, fever, jaundice, or continued bilious drainage from a surgical drain. Whereas computed tomography (CT) and sonography are sensitive in detecting perihepatic or free peritoneal fluid collections, they are nonspecific and definitive diagnosis of biliary tract injury requires hepatobiliary scintigraphy, endoscopic retrograde cholangiopancreatography (ERCP), percutaneous transhepatic cholangiography (PTC), or percutaneous aspiration. Disruption of the biliary tree has commonly been treated with reoperation or percutaneous drainage. More recently, endoscopic management has shown encouraging results for bile leaks and strictures in small series.

Gallium-67 imaging and computed tomography in early retroperitoneal fibrosis.

Retroperitoneal fibrosis is characterized by symptoms associated with gradual compression of retroperitoneal structures. This case report demonstrates the use of Ga-67 imaging and CT in the early diagnostic work-up of this disorder.

Ga-67 scintigraphy and computed tomography in the diagnosis of pneumocystis carinii pneumonia in patients with AIDS. A prospective comparison.

A prospective evaluation of Ga-67 scintigraphy and transmission computed tomography was performed in 70 consecutive patients with AIDS who were suspected of having Pneumocystis carinii pneumonia. Studies were evaluated independently by two observers. Receiver operating characteristic curves were plotted. Although scintigraphy had a higher true-positive ratio at any false-positive ratio, statistically the areas under the two receiver operating characteristic curves were not significantly different. However, at an FP rate of 15% to 20% (one in the clinically reasonable range), the sensitivity for scintigraphy was 0.84 and for CT 0.80; corresponding specificities were 0.82 and 0.64, respectively, for the two modalities. It seems from these data that gallium imaging is probably superior to CT in detecting P. carinii pneumonia in this group of patients.

The complementary role of SPECT in the diagnosis of cavernous hemangioma of the liver.

Cavernous hemangiomas are the most common benign tumors of the liver. Although their clinical course is usually uncomplicated, an accurate diagnosis may be important to exclude conditions that need treatment, (or to avoid an unnecessarily risky percutaneous biopsy). Although blood pool scintigraphy using planar gamma camera imaging is a reliable examination for the diagnosis of liver hemangiomas, it may fail to depict small, deeply seated lesions, and hence miss the diagnosis. Two cases are reported in which SPECT demonstrated delayed pooling in small, deep, space-occupying lesions, which were poorly seen on planar images, and therefore made a cavernous hemangioma the most likely diagnosis.

Chronic osteomyelitis: the relative roles of scintigrams, plain radiographs, and transmission computed tomography.

We evaluated the relative contribution of transmission computed tomograms (CT), plain radiographs, and bone/gallium scans in the diagnosis of 27 patients with suspected active chronic osteomyelitis. All patients were imaged with all modalities and had surgical proof of the presence or absence of disease. At surgery, osteomyelitis was shown to be active in 20 patients, 15 of whom had sequestra, and inactive in the remaining seven. CT depicted all 15 sequestra, but was falsely positive in three patients, all of whom had bone remodeling only and had negative bone/gallium scintiscans. Plain radiographs had a limited value; they detected sequestra, which was the only findings to indicate the presence of active disease, in 5 patients out of the 15 with surgical proof thereof. The authors conclude that, considering the shortcoming of other modalities with regard to depicting sequestra, scintigraphy is helpful in confirming the presence or absence of active disease and therefore in preventing unnecessary surgery.

Detection of hepatic metastases in diffuse fatty infiltration by CT: the complementary role of imaging.

Six patients undergoing computed tomographic (CT) evaluation for possible abdominal and pelvic metastases were shown to have diffuse fatty infiltration of the liver and findings indeterminate for hepatic metastases. In two patients with diffuse fatty infiltration and no focal hepatic lesions on CT, technetium-99m sulfur colloid imaging demonstrated focal hepatic defects confirmed to represent metastases. In four patients with diffuse fatty infiltration and hyperdense liver foci on CT, radionuclide imaging demonstrated normal uptake in the hyperdense foci confirmed to represent areas of normal liver spared by fatty infiltration. In each of the six patients, clinical management was altered by the radionuclide findings.

Viral encephalitis: imaging with SPECT.

SPECT brain imaging performed in two patients with presumed herpes encephalitis demonstrated greater sensitivity and more precise localization than either planar brain imaging or CT scanning.

Myocardial clearance of Tc-99m hexakis-2-methoxy-2-methylpropyl isonitrile (MIBI) in patients with coronary artery disease.

Myocardial clearance of the new cationic, lypophilic myocardial perfusion agent, Tc-99m-hexakis-2-methoxy-2-methylpropyl isonitrile (MIBI) was studied in nine patients with coronary artery disease. Regional time-activity curves were determined from serial postexercise myocardial SPECT images after a single dose of Tc-99m MIBI. There were significant differences between the clearance rates from normal and ischemic myocardium. Tc-99m MIBI washout from normal myocardium was 27 +/- 8% by 6 hours after injection. Clearance from mild myocardial defects (initial activity greater than 60% of the activity in normal myocardium) was 16% by 6 hours in six patients. No washout was detected by 6 hours in the three patients with severe myocardial defects. The ratio between the activity in ischemic and normal myocardium increased from 0.70 +/- 0.08 to 0.80 +/- 0.13 and 0.84 +/- 0.13 at 4 and 6 hours after injection in the patients with mild defects. In the patients with large defects, the ratio increased from 0.42 +/- 0.09 to 0.54 +/- 0.07 at 6 hours. It is concluded that, while redistribution is substantially slower than with Tl-201, image interpretation and data evaluation should be approached cautiously when imaging is delayed 4 hours or more after injection of Tc-99m MIBI. Quantitative techniques aimed at evaluating the extent and intensity of myocardial ischemia will be particularly affected.