Consecutive brain SPECT surface three-dimensional displays show progression of cerebral cortical abnormalities in Alzheimer's disease

PURPOSE: To monitor progression of cerebral blood flow deterioration, this study used consecutive surface SPECT to evaluate the feasibility of brain surface displays (BSD) to follow Alzheimer's disease (AD) to determine whether overtime is a consistent feature of the disease. METHODS: Eighteen men (mean age, 75.7 years) with probable Alzheimer's disease (AD), with moderate to profound dementia indicated by the Mini-Mental State Examination (MMSE; median score, 10; range, 0 to 19), underwent brain Tc-99m ethyl cysteinate dimer SPECT. Brain SPECTs were obtained using a three-head gamma camera. Brain surface displays (BSD) were reconstructed from transaxial data using a threshold of 55% of the maximum pixel count. A second series of SPECTs were obtained after 5 to 23 months (except for one, which was done after 60 months). Each BSD was graded semiquantitatively, by visual interpretation, from zero to 8 (normal = 0, mild = 2, moderate = 4, severe = 6, and profound = 8) depending on the extent of the perfusion defects in the frontal, temporal, or parietal (or all of these) pattern of AD. MMSE scores were used to calculate "time index" values for estimating severity at the time of the SPECTs. RESULTS: The initial BSD scores correlated significantly with dementia severity (r = 0.71, P < 0.001). All 18 patients had decreased blood flow on consecutive SPECTs. Scores for BSD progressed at a rate of 2.5 +/- 1.7 points per year and correlated significantly with the time interval between the scans (r = 0.71; P < 0.001). CONCLUSIONS: The BSDs of SPECT scan data have considerable objective discriminatory power for assessing the severity and progression of AD-related hypoperfusion, particularly in the moderate to profound dementia ranges, and is potentially more reliable than the MMSE. Consecutive BSDs simplify SPECT image interpretation for measuring loss of brain function over time and could be useful for assessing the efficacy of therapeutic interventions for AD patients such as vitamin E and cholinesterase inhibitors.

Normal variants of a photon-deficient area in the lower sternum demonstrated by bone SPECT.

PURPOSE: A highly variable normal appearance of the sternal area makes interpretation difficult on planar bone imaging. These normal variants occur especially in the area above the xiphoid process of the sternum in which an oval photopenic area on anterior planar images may be seen. This finding is most likely caused by localized incomplete fusion. METHODS: Of a group of 188 patients, 35 patients (33 men, 2 women; age range, 30 to 85 years; mean age, 57 years) were examined with sternal SPECT and planar bone imaging. These patients, who had no history of sternal trauma, surgery, radiation, or infection, were referred for bone scan for metastatic work-up (n = 20), back pain (n = 6), and other conditions (n = 9). Thus 11 of 35 (31%) patients had a SPECT study that showed a photopenic area in the lower sternum. RESULTS: The incidence of this normal variant was higher than the 2% to 7.7% previously reported, indicating improved detection by SPECT. The normal variant appears to be less apparent on planar bone images and is seen more clearly on SPECT images. CONCLUSION: Differentiation from malignancy appears to be related to lesion symmetry, location, midline, and evenly distributed radioactivity surrounding the edge of the photopenic area.

Myositis ossificans demonstrated by positive gallium-67 and technetium-99m-HMDP bone imaging but negative technetium-99m-MIBI imaging.

Gallium-67-citrate and 99mTc-diphosphate bone imaging agents are localized in myositis ossificans, a tumor-like benign soft-tissue mass that makes it impossible to differentiate between malignant tumor and the infection/inflammatory process. We present such a myositis ossificans patient whose bone and 67Ga-citrate imagings showed increased uptake in the left thigh and two foci of the right gluteal region leading to inconclusive results. Technetium-99m-MIBI imaging showed the absence of substantial uptake in these regions. ACT scan confirmed myositis ossificans. The lack of 99mTc-MIBI uptake in myositis ossificans means that 99mTc-MIBI imaging may be useful in the differential diagnosis.

Tc-99m MIBI thoracic SPECT for the detection of intrathoracic tumor masses.

Thirty-one men (age range, 46-76 years; mean age, 64.8 years) with intrathoracic masses suggesting possible malignancy on the basis of chest radiography or CT underwent preoperative Tc-99m MIBI SPECT examinations. Diagnosis was confirmed on pathologic examinations of samples obtained either at thoracotomy, esophagectomy, or by biopsy. Twenty-five patients had primary lung cancer, including squamous cell carcinoma, large cell carcinoma, adenocarcinoma, and small cell carcinoma. Two patients had lymphomas with spread to the mediastinum, and three patients had extrathoracic primary cancers (one squamous cell carcinoma of esophagus, one squamous cell carcinoma originating from a head and neck tumor, and one metastatic mediastinal leiomyosarcoma). One patient with a tuberculoma had negative results of the Tc-99m MIBI examination. Tc-99m MIBI had a 86.7% sensitivity rate, a 0% false-positive rate, and a 100% positive predictive value to detect malignant intrathoracic masses. There was a 13% false-negative rate, however, suggesting that MIBI-SPECT may underdiagnose malignant lesions. SPECT findings of these 31 patients can be classified as 1) mass with increased uptake, n = 23; 2) ring-like appearance of increased uptake, n = 3; 3) mass with absent uptake, n = 4; and 4) photon-deficient mass, n = 1. Absent uptake in patients with mass lesions could be explained by necrosis of the lesion (caseation necrosis or massive tumor necrosis with or without bleeding). Most malignant intrathoracic masses are Tc-99m MIBI avid and may be detected with a high degree of sensitivity and with an excellent positive predictive value. A positive MIBI scan may help in the clinical diagnosis of malignancy. The use of Tc-99m MIBI could serve not only as a tumor imaging agent, but also may be used to determine the extent of spread and potentially the chemotherapeutic responsiveness of a tumor.

Functional retention of Tc-99m MIBI in mediastinal lymphomas as a predictor of chemotherapeutic response demonstrated by consecutive thoracic SPECT imaging.

Tc-99m MIBI is used as a tumor imaging agent and has been proposed to measure p-glycoprotein function, which plays an important role in tumor multidrug resistance to chemotherapy. It has been reported that lung cancer and breast cancer with a high retention of Tc-99m MIBI have been more responsive to chemotherapy than tumors with low retention. Thus Tc-99m MIBI SPECT could be used as a measure of p glycoprotein function and consequently may serve as a predictor of the tumor's responsiveness to chemotherapeutic agents. Described here are two patients with lymphomas, one with non-Hodgkin's lymphoma and the other with Hodgkin's disease, who underwent Tc-99m MIBI thoracic SPECT before and after chemotherapy. The sequential studies demonstrated a reduction in tumor size and diminished tumor uptake in one patient and disappearance of tumor uptake after a course of chemotherapy in the other patient. The data suggest that elevated Tc-99m MIBI uptake in a tumor as a result of retention by p glycoprotein not only demonstrates mediastinal involvement of lymphomas but also may be used to forecast responsiveness to chemotherapy.

An unusual case of a tibial metastasis as the clinical presentation of bronchogenic adenocarcinoma.

A patient with initial complaints of leg pain and difficulty walking was found to have a large right tibial metastatic tumor and poorly differentiated adenocarcinoma of the lung. Findings from total-body bone scintigraphy include a large area of increased uptake in the proximal half of the right tibia with a photon-deficient area medially, and focal areas of uptake in a right rib, in the femoral neck and the left ileum. An irregular area of increased uptake in the left lung mass was shown by thoracic bone SPECT. This is an unusual case of a tibial metastasis as the first clinical presentation of bronchogenic adenocarcinoma.

Ring appearance of Tc-99m MIBI thoracic SPECTs and increased uptake on Tc-99m HMDP thoracic SPECTs in a pulmonary mass of small cell carcinoma.

Tc-99m MIBI is taken up avidly by viable tumor tissue and does not accumulate in the necrotic carcinoma. We present a patient who underwent Tc-99m MIBI and Tc-99m HMDP thoracic SPECTs: a large area of increased MIBI uptake with central photopenia (ring appearance) in the right upper lung localizes bone imaging agent and does not localize multiple areas of intense uptake in the metastatic hilar mediastinum lymph nodes. Rapid growth of tumor cells in the lung leading to central necrosis/ischemia accounts for bone imaging agent localization in the tumor, as well as the ring-appearance of lung mass on Tc-99m MIBI imaging. These findings may reflect less viability of the lung tumor as compared with intense MIBI uptake in hilar/mediastinal lymph node uptake without bone agent localization.

A mural thrombus of an infrarenal aortic aneurysm demonstrated as photon deficiency in a radionuclide study.

Radionuclide angiogram (RNA) and aortogram may underestimate external aneurysmal diameter. Photon deficient areas are not uncommon along the abdominal aortic aneurysm (AAA) on RNA. To determine whether or not photon deficient areas along the aneurysm could represent a large thrombus, we studied radionuclide aortic angiography in thirty-eight patients during a preoperative cardiac gated study. All the patients (men, ages from 60 to 78) had CT, US, and/or aortogram for comparison. The presence of a thrombus was determined by CT, US, and/or surgical findings. Twelve of 38 (32%) patients' RNA and blood pool images showed photon deficient areas along the aneurysmal walls having a large concentric or eccentric thrombus of the AAA. A large photon deficient area could be detected along the narrowing calibre of the aorta lumen. This finding results from a large mural thrombus being interposed between the left or right bowel/mesentery activity and the activity of the aneurysms functioning patent lumen. We concluded that a photon deficient area along an inferorenal aortic aneurysm may indicate a large thrombus of either eccentric or concentric type within an AAA.

Medullary thyroid carcinoma imaged by Tc-99m MIBI SPECT and Tl-201 chloride/Tc-99m pertechnetate subtraction SPECT.

A 61-year-old man with medullary thyroid carcinoma and local invasion of the left lobe of the thyroid had Tc-99m MIBI SPECT and Tl-201 chloride/Tc-99m pertechnetate subtraction SPECT after left lobectomy of the thyroid, using a triple-headed gamma camera. Tl-201 chloride/Tc-99m pertechnetate subtraction demonstrated a large mass with high Tl-201 uptake in the left neck. Although there was intense uptake in the tumor in the left thyroid bed on Tc-99m MIBI neck SPECT, there was also uptake in both salivary glands and the right lobe of the thyroid gland. Thus, uptake in the right lobe of the thyroid gland and the salivary glands might not be differentiated from tumor invasion or metastasis from medullary cell carcinoma. Compared with MIBI SPECT, Tl-201 chloride/Tc-99m pertechnetate subtraction SPECT shows more apparent delineation of tumor uptake and may be a preferable technique.

Reverse redistribution on dynamic exercise and dipyridamole stress technetium-99m-MIBI myocardial SPECT.

Reverse redistribution on 201TI-chloride stress-redistribution myocardial scintigraphy has been associated with coronary artery stenosis. We report a patient whose two separate 99mTc-MIBI myocardial SPECT stress studies (dynamic exercise and dipyridamole) showed septal reverse redistribution and fixed inferior defect. Echocardiograms showed left ventricular (LV) hypertrophy and diffuse hypokinesis, especially in the inferior wall, and EKG showed LV hypertrophy and strain and inferior infarct. Coronary angiogram confirmed two-vessel disease involving 80%-90% stenosis of the proximal second diagonal branch of the left anterior descending artery and 75%-90% stenosis of the right coronary artery as well as global left ventricular dysfunction. Reverse redistribution on 99mTc-MIBI myocardial SPECT occurring on dynamic or dipyridamole stress may indicate damaged but viable myocardium.

Surface and volume three-dimensional displays of Tc-99m HMPAO brain SPECT images in stroke patients by a three-headed gamma camera.

Twenty patients with strokes were studied to evaluate volume and surface three-dimensional (3D) displays in Tc-99m HMPAO brain SPECT imaging using a triple-head gamma camera interfaced with a 64-bit super computer. In each patient, after an intravenous injection of 20 to 30 mCi of Tc-99m HMPAO, a first-pass cerebral flow study and brain SPECT images at 30 to 60 minutes were obtained. Although the cerebral lesion was more clearly delineated with surface 3D and volume 3D, crossed cerebellar diaschisis in seven patients was more clearly exhibited by volume 3D rather than surface 3D imaging. Volume and surface 3D displays enhance continuity of structures and understanding of spatial relationships; these displays view the brain from all angles, and thus the location and extension of lesion(s) in the brain are much easier to appreciate. It is concluded that 1) both surface and volume 3D displays equally enhance SPECT interpretation; and 2) volume 3D display enhances demonstration of crossed cerebellar diaschisis, but surface 3D display does not.

Extracardiac 'hot' and 'cold' areas on thallium-201 myocardial SPECT imaging.

A 72-year-old man underwent Persantine 201Tl myocardial SPECT imaging that showed a transient area of extracardiac radiotracer accumulation inferior to the inferior wall of the left cardiac ventricle, and a persistent, rounded, cold area in the liver. CT of the abdomen confirmed a cystic lesion in the liver corresponding to the cold area, and the transient extracardiac tracer accumulation area corresponded to a large aneurysm of the distal descending thoracic aorta. An extracardiac abnormal area of 201Tl localization, 'hot' or 'cold', should be included for scan interpretation to depict thoracic and/or upper abdominal lesions(s).

Intraventricular photon deficiency in gated cardiac blood pool imaging due to left ventricular metastases from renal cell carcinoma.

Cardiac metastasis can occur with any widely disseminated malignancy, especially from carcinoma of the kidney, stomach, lung, breast, or from melanocarcinoma. Metastasis to the myocardium can protrude from the endocardium into the intraventricular cavity of the left ventricle. We present a case of renal cell carcinoma and left ventricle cavitary metastases, documented by an echocardiogram demonstrated in a cardiac blood pool study as a photon-deficient area in the left ventricle cavity.

Extracardiac intrathoracic abnormalities demonstrated by Tc-99m RBC gated blood pool imaging.

In addition to intrathoracic great vessel abnormality, pericardial effusion, and splenomegaly, extracardiac intrathoracic abnormalities were found in 12 of 210 patients' 99mTc red blood cell (RBC) gated cardiac blood pool imagings. These abnormalities, including five cases of absent pulmonary perfusion due to tumor mass, four of pleural effusion, two of pneumothorax, and one of left lung mass attenuation, were confirmed with concurrent or subsequent chest radiography, chest CTs, or biopsy. Pulmonary blood pool activity is normally seen on both sides in both anterior and left anterior oblique views; decreased or absent perfusion on either side or in part of the lung may indicate chest/pulmonary pathologies. Although pulmonary and thoracic wall lesions are not frequently seen, such incidental findings during gated cardiac blood pool imagings can lead to further study for these clinically unsuspected lesions and may benefit the patient.

Cholescintigraphy in the detection of cholelithiasis: a review of 23 cases and a case report demonstrating the sequential evolution of the appearance of the gallbladder defect.

Cholescintigraphy of cholelithiasis has been reported as a defect or photon deficient area in the gallbladder. We present the case of a patient with gallstones whose cholescintigraphic study showed a sequential evaluation of the scan appearance from a defect, to a septation, a hole, and finally a filled-in appearance. Cholescintigrams and histopathologic findings after cholecystectomy of another 22 patients with cholelithiasis were also retrospectively reviewed. The results of the study concluded that: cholelithiasis is rarely demonstrated by cholescintigraphy and nonvisualization of the gallbladder may be due to acute or chronic cholecystitis associated with cholelithiasis.