Increased bone marrow blood flow in sickle cell anemia demonstrated by thallium-201 and Tc-99m human albumin microspheres

Lower extremity vascularity in nine patients with sickle cell anemia was studied by intra-arterial Tc-99m human albumin microspheres or intravenous thallium 201. In eight patients, the normal pattern of greater muscle than bone activity was reversed with marked tracer localization in skeletal parts usually not visualized. In four cases, there were distinct focal abnormalities in the femurs and tibias which correlated with defects on Tc-99m sulfur colloid marrow scans. Tc-99m pyrophosphate bone scans demonstrated normal uptake in the same areas. The scintigraphic findings indicate a markedly increased relative bone marrow blood flow.     

The role of Tc-99m (V) DMSA scintigraphy in the evaluation of superscan on bone scintigraphy

PURPOSE: This study evaluated the biodistribution of Tc-99m (V) DMSA in patients with superscans on bone imaging and defined its role in differentiating the underlying cause. METHODS: Nine patients (five with metastatic and four with metabolic bone disease) with classical superscans were entered into the study. All patients had the necessary radiologic and biochemical studies and a final diagnosis was reached accordingly. Tc-99m (V) DMSA scintigraphy was performed 1 week after Tc-99m MDP whole-body bone imaging. RESULTS: In four of five patients with widespread skeletal metastases, Tc-99m (V) DMSA scan showed diffusely increased bone uptake. In the remaining patient, the Tc-99m (V) DMSA scan showed a normal distribution pattern. All patients with metabolic bone disease had increased bone uptake on Tc-99m (V) DMSA scans. CONCLUSION: Tc-99m (V) DMSA shows increased bone uptake in patients having a superscan appearance in metastatic or metabolic bone disease. Tc-99m (V) DMSA imaging may play a role in the evaluation of patients with equivocal bone scan findings for a superscan.     

Tl-201 uptake in brown tumors of hyperparathyroidism.

Tl-201 chloride bone scans were performed on nine patients with primary hyperparathyroidism just after Tl-201 and Tc-99m parathyroid subtraction scintigraphy. Bone lesions accumulate Tl-201, especially in sites of brown tumor formation. This was proven by the histopathologic examination of two patients. Eight patients had bone scans with Tc-99m MDP. The lesion-to-background ratio was quantified in seven patients for Tl-201 and in four patients for Tc-99m MDP. Tl-201 uptake of the lesions were quantified in two patients. The lesion-to-background ratio was 1.63 +/- 0.21 and 2.51 +/- 0.88 for Tl-201 and Tc-99m MDP, respectively. A Ga-67 citrate scan was performed on one patient, and the lesion-to-background ratio was 1.49 +/- 0.06. The accumulation of Tl-201 in brown tumors of bone might be due to increased blood flow and local metabolic activity. Tl-201 chloride was inferior to Tc-99m MDP in lesion detection. It is concluded that bone imaging with Tl-201 can easily be performed following parathyroid subtraction scintigraphy to delineate the sites of brown tumor formation.     

Tc-99m-HMDP bone uptake quantification and plasma osteocalcin levels in hemodialysis patients—A preliminary study

In this preliminary study plasma osteocalcin levels and Tc-99m-HMDP (Technetium 99m hydroxymetylene diphosphonate) bone uptake (BU) were measured in 10 chronic end-stage renal failure patients who were on maintenance hemodialysis. The aim of this study was to determine the correlation between bone uptake and osteocalcin-a sensitive and specific marker of osteoblastic activity. There was a statistically significant increase in both 20 and 180 minute uptake in the patient group (36 +/- 2.7 and 39 +/- 3.6) when compared to the normal volunteers (32 +/- 3.1 and 19 +/- 2.7). Plasma osteocalcin levels were also significantly high (24.5 +/- 5.6 ng/ml) when compared with normal values (6.5 +/- 2.3 ng/ml). The correlations between osteocalcin and 20 and 180 min BU were high (r = 0.62 and 0.72 respectively). In conclusion, our preliminary study suggests that, in hemodialysis patients, Tc-99m-HMDP bone uptake quantification is a sensitive and non-invasive method for showing increased osteoblastic activity.     

Dichotomy between Tc-99m MDP bone scan and fluorine-18 fluorodeoxyglucose coincidence detection positron emission tomography in patients with non-Hodgkin's lymphoma

The authors report two cases of non-Hodgkin's lymphoma that were evaluated not only by conventional staging work-up but also additional Tc-99m MDP bone scans and fluorine-18 fluorodeoxyglucose (F-18 FDG) coincidence detection (CoDe) positron emission tomographic (PET) imaging. There were discordant results between the Tc-99m MDP bone scans and F-18 FDG CoDe PET. In the first case, the bone marrow biopsy was positive, and F-18 FDG CoDe PET was consistent with a malignancy, but the findings of the Tc-99m MDP bone scintiscan were negative. In the second case, the bone marrow biopsy was negative, but F-18 FDG CoDe PET revealed focal skeletal involvement, which improved markedly on the follow-up study after chemotherapy. If skeletal involvement has a focal distribution and is confined to the marrow cavity, both bone marrow biopsy and bone scintigraphy can be falsely negative. In this situation, F-18 FDG PET is useful and revealing.     

Tc-99m MIBI parathyroid scintigraphy and intact parathyroid hormone levels in hyperparathyroidism

Tc-99m MIBI has been widely used to evaluate hyperparathyroidism based on increased tracer uptake in hyperfunctioning parathyroid tissue. The functional status measurement of parathyroid glands with intact parathyroid hormone (iPTH) levels is also one of the most important diagnostic studies in this disorder. The aim of the current study was to assess the relation between MIBI imaging and iPTH levels. The authors retrospectively reviewed the records of patients with hyperparathyroidism who were referred to their department for Tc-99m MIBI scintigraphy. Sixty-five patients (24 primary and 41 secondary hyperparathyroidism) were included. The iPTH levels ranged from 66.06 to 2,836 pg/ml (normal, 10 to 55 pg/ml). Forty-two patients were MIBI positive and 23 were negative. The iPTH level in the MIBI-positive group was significantly greater than in the negative group in the primary (548 +/- 478 versus 124 +/- 45; = 0.002), secondary (1,155 +/- 692 versus 501 +/- 352; < 0.001), and overall (909 +/- 678 versus 386 +/- 341; < 0.001) groups. For the primary hyperparathyroidism group, 17 of the 24 patients were MIBI positive (71%). When iPTH levels exceeded 200 pg/ml (100%), the diagnostic sensitivity reached 100%. For the secondary hyperparathyroidism group, 25 of 41 patients (61%) were MIBI positive; 24 of 38 patients (63%) had an iPTH level greater than 200 pg/ml, 21 of 27 patients (78%) had an iPTH level greater than 500 pg/ml, and 11 of 12 patients (92%) had an iPTH value greater than 1,000 pg/ml. Tc-99m MIBI parathyroid scintigraphy showed a good correlation with iPTH level for both primary and secondary hyperparathyroidism. Visualization of hyperfunctioning parathyroid glands on Tc-99m MIBI parathyroid scintigraphy was more likely with a higher serum iPTH level in a dose-dependent manner.     

Intracranial extramedullary hematopoiesis. CT and bone marrow scan findings

This case concerns a patient with intracranial extramedullary hematopoiesis (EH) suspected on a CT scan and subsequently confirmed with In-111 chloride and Tc-99m SC bone marrow scans. The bone marrow scans also provided additional information by demonstrating other sites of EH in the paravertebral tissues and bone marrow expansion into the distal extremities.     

Pathologic fractures in a patient with renal osteodystrophy. Failure of early detection on bone scans

A case of false-negative Tc-99m MDP bone scintigrams, taken at one and two weeks for pathologic fractures in a patient with metabolic bone disease and a super-scan appearance, is described. The patient had renal osteodystrophy, and postparathyroidectomy hypocalcemia. Postoperative seizures caused multiple pathologic fractures. Initial scans were negative for focal tracer localization in the presence of a continued super-scan appearance. After months of calcium and vitamin D replacement therapy, fracture sites became positive on Tc-99m MDP imaging. The observations in this case lend credence to the hypothesis of Tc-99m MDP binding by immature collagen in the production of a super scan in metabolic bone disease, as well as that of Tc-99m MDP chemisorption to calcium hydroxyapatite crystal in fracture healing. In addition, aluminum toxicity, common in chronic renal osteodystrophy, may have played a role in the delayed fracture healing.     

Testicular lymphoma with bone/bone marrow metastases illustrated by scrotal sonography, spinal MRI, and total body Tc-99m HMDP and Tc-99m MIBI imagines

An 83-year-old man with testicular lymphoma demonstrated progressive scrotal enlargement with non-homogeneity sonographically and abnormally increased uptake in the scrotum of Tc-99m HMDP and Tc-99m MIBI scintigraphically. Extensive bone/bone marrow metastases were exhibited by Tc-99m MIBI and Tc-99m HMDP scintigraphies and MRI of the spine. In addition, focal/tubular activity of the femoral bone marrow on Tc-99m MIBI imaging was consistent with skeletal scintigraphic findings. It is emphasized that Tc-99m MIBI total body imaging enabled the demonstration of testicular lymphoma as increased uptake and the illustration of skeletal/bone marrow metastases as diffuse and/or focal increased uptake, especially focal/tubular MIBI activity of the femoral marrow.     

Tc-99m(V) DMSA imaging. A new approach to studying metastases from breast carcinoma.

Combined Tc-99m MDP skeletal imaging and Tc-99m(V) DMSA whole body scans to detect metastases were performed during the follow-up of 30 patients who underwent surgery for breast carcinoma. Eight patients had normal Tc-99m MDP and Tc-99m(V) DMSA scans and were declared free of metastatic disease, further confirmed by no change in symptomatology over a 1-year follow-up period. Twenty-two patients had positive Tc-99m MDP scans with varied skeletal involvement. Tc-99m(V) DMSA scans showed matched areas of increased radiotracer concentration in bony metastases in 20 of these patients. Tc-99m(V) DMSA concentration was not seen in traumatic vertebral collapse or in coexistent osteoarthritic disease in vertebral metastatic involvement. Interestingly, Tc-99m(V) DMSA showed increased concentration in brain and liver metastases. Pentavalent Tc-99m(V) DMSA appears useful for detecting skeletal and soft-tissue metastases in breast carcinoma, and can improve the specificity of Tc-99m MDP bone scans in screening for bone metastases.     

The role of Tc-99m (V) DMSA scintigraphy in the diagnosis and follow-up of lung cancer lesions

Objective To define the role of Tc-99m (V) dimercaptosuccinic acid (DMSA) scanning in the detection of lung cancer (LC) and its metastases, and monitoring the response of LC lesions (LCL) to chemo/radiotherapy (TH). Methods Tc-99m (V) DMSA whole-body scans, planar thorax views, and thorax Single-photon emission computed tomography (SPECT) images were obtained both 30 min (early) and 5 h (late) after Tc-99m (V) DMSA administration in 12 small/nonsmall cell LC patients (11 men, 1 woman; mean age 59 years). Five patients also had bone scans. The same scintigraphic protocol was performed in 7 of 12 patients, 3 weeks after first-line TH. TH response was evaluated visually in all LCL and semiquantitatively in primary tumors (PT) of six patients, by comparing the tumor uptake ratios (TUR) of pre-TH and post-TH Tc-99m (V) DMSA SPECT [TUR = mean counts of region of interests (ROI) in PT/mean counts in contralateral ROI]. In seven patients, a 6-month survival was determined. Results Tc-99m (V) DMSA accumulated in 34 LCL (11 PT, 19 bone metastases, 1 suprarenal mass, 1 axillary node, 2 supraclavicular nodes). A total of 11 patients displayed Tc-99m (V) DMSA uptake in LCL and one patient did not show uptake. In six patients, SPECT imaging showed deeply located PT in the lung parenchyma better than planar views. In five patients, both planar and SPECT views revealed peripherally located PT in the lungs. Early scans showed 18 LCL and late scans displayed all the LCL. Nine bone metastases on pre-TH Tc-99m (V) DMSA scans revealed matched areas of increased Tc-99m methylene diphosphonate (MDP) uptake on bone scans; six bone metastases were additionally detected on Tc-99m (V) DMSA scans when compared with bone scans, and four bone metastases on Tc-99m (V) DMSA scans could not be compared with bone scans because bone scan was not performed. In one patient, Tc-99m (V) DMSA scans became positive for bone metastases on post-TH later than the bone scans for some of the bone metastases. Neither planar nor SPECT imaging showed mediastinal lesions defined on thorax CT in nine patients. On TH monitoring, 17 LCL showed diminished Tc-99m (V) DMSA uptake, one disappeared, four were unchanged, three displayed increased uptake, and five new lesions were established. Of the six patients, TUR in PT increased in two (one survived), decreased in one (exitus), was unchanged in two (two exitus) on post-TH scans, and PT totally disappeared in one (survived) patient. Conclusions Tc-99m (V) DMSA scans are useful in detecting LCL, except for those around the blood pool regions, making it a promising modality to monitor TH response. Obtaining a single fifth hour late Tc-99m (V) DMSA scan is appropriate. SPECT should be applied to all patients for the detection of deeply located lesions.     

Gaucher's disease type 1: assessment of bone involvement by CT and scintigraphy

The effectiveness of CT and technetium-99m sulfur colloid (99mTc SC) bone-marrow scans in determining the extent and severity of skeletal involvement in 23 patients with type 1 Gaucher's disease was compared with the effectiveness of conventional radiographic techniques and technetium-99m methylene diphosphonate (99mTc MDP) bone scintigrams. Density measurements obtained by CT proved sensitive in differentiating normal marrow (-50 to -120 H). Scintigrams with the sulfur colloid nuclide demonstrated three distinct patterns of uptake: peripheral expansion of normal marrow (profile B), greater marrow expansion with patchy areas lacking uptake (profile C), and greater loss of uptake with retention of the nuclide in other reticuloendothelial organs and circulation (profile D). CT scans provided greater sensitivity in resolving the extent of marrow involvement in affected areas, while the 99mTc SC scintigrams were more effective in overall assessment of the severity of bone-marrow involvement. Both conventional radiographic techniques and 99mTc MDP bone scans were useful primarily as screening procedures or for evaluating specific involved areas. 99mTc MDP scans were useful in evaluating regional defects (i.e., ischemic necrosis) in certain cases, but no consistent patterns were observed. CT and 99mTc SC scans are useful for determining the extent and severity of Gaucher's disease involvement of bone marrow.     

Technetium-99m human immunoglobulin scintigraphy in patients with adhesive capsulitis: a correlative study with bone scintigraphy

Adhesive capsulitis (AC) is a disorder that is characterized by shoulder pain and progressive limitation of both active and passive shoulder motion. Although the underlying pathological mechanisms of the disease are not well understood, the inflammatory reactions depending on the stage have been demonstrated histologically. The purpose of the study is to investigate the inflammatory changes that can be demonstrated with Tc-99m HIG in AC, and to determine the presence of correlations between scintigraphic findings and the clinical assessment. Twenty-one patients (12 females and 9 males) with a mean age of 50.57+/-8.49 were included in the study. AC was diagnosed according to recognized criteria. The planar X-ray images of the affected shoulders of all patients were normal. The patients were evaluated with the Constant Scoring System, and the functional and pain assessment parts of the American Shoulder and Elbow Surgeons' Form (ASES). Three phase bone scans and Tc-99m HIG scintigraphy were performed at least two days apart. Bone scan and Tc-99m HIG scintigraphy were evaluated visually and HIG uptake was evaluated in comparison with the contralateral normal shoulder. Bone scan demonstrated hypervascularity in 9 of the 21 patients (43%), whereas increased osteoblastic activity was detected in 19 (90%) in the affected shoulder. Tc-99m HIG uptake was positive in 12 (57%), and negative in 9 (43%) patients. All patients with increased Tc-99m HIG accumulation in the affected shoulder, also had increased osteoblastic activity on Tc-99m bone scintigraphy. A significant correlation was found between HIG uptake and constant, functional and pain scores. The difference between these scores was also statistically significant in patients with HIG positive and negative uptake. This study indicates that there is a good correlation between Tc-99m HIG scan findings and clinical scores. Tc-99m HIG accumulation in the affected shoulder may be related to continuing inflammatory reaction to AC. Tc-99m HIG scan may be a noninvasive, complementary method for demonstrating continuing inflammatory changes and may help in staging the disease.     

Predictive value of bone marrow accumulation of Tc-99m tetrofosmin for subsequent development of distant metastases in breast cancer

OBJECTIVE: We evaluated the predictive value of bone marrow accumulation of technetium (Tc)-99m tetrofosmin in patients with breast cancer for distant metastases in comparison with conventional prognostic factors such as clinical stage, tumor size, axillary lymph node (Node) status, and estrogen receptor (ER) status. METHODS: Bone marrow scans with Tc-99m tetrofosmin were performed on 64 patients with breast cancer who had no clinical evidence of distant metastases. Accumulation in the femoral marrow was classified into four patterns, no detectable, lower, higher, and intensively higher. Higher or intensively higher pattern was interpreted as abnormal. Thirty-six patients with abnormal accumulation (marrow-positive group) and 28 patients without abnormal accumulation (marrow-negative group) were enrolled in the follow-up study. The mean length of observation after scans was approximately 3 years. The predictive value of femoral marrow status and conventional prognostic factors for distant metastases was evaluated by statistical analysis. RESULTS: Univariate analysis showed a significantly higher incidence of subsequent bone metastases (36%>4%; P<0.005), and distant metastases (69%>18%; P<0.001) in the marrow-positive group when compared with the marrow-negative group. Conventional prognostic factors except tumor size were also significantly associated with the development of distant metastases; 77% in clinical stage 3>39% in clinical stages 1, 2, P<0.05; 64% in Node-positive>29% in Node-negative, P<0.01; and 70% in ER negative>27% in ER positive, P<0.005. These conventional factors were not significantly associated with bone metastases. The Cox proportional hazard ratio for bone metastases was markedly higher in femoral marrow status (hazard ratio=11.07). The distant metastases-free survival was significantly reduced in ER negative (P<0.0005), Node-positive (P=0.0215), and clinical stage 3 patients (P=0.0163). On the other hand, a more marked difference was observed in the femoral marrow status (P<0.0001). The hazard ratio for distant metastases was 2.44 in clinical stage, 2.74 in tumor size, 2.74 in Node, and 3.68 in ER, which were each independent prognostic factors associated with distant metastases. However, femoral marrow status was markedly associated with distant metastases (hazard ratio=5.27). CONCLUSIONS: Bone marrow accumulation of Tc-99m tetrofosmin can be a promising prognostic factor independent of conventional prognostic factors for predicting development of not only bone metastases but also distant metastases in breast cancer.     

Technetium-99m diphosphonate imaging of psammocarcinoma of probable ovarian origin: case report and literature review

Technetium-99m methylene diphosphonate (Tc-99m MDP) bone scans have long been used by clinicians to diagnose osseous metastases in patients with cancer. However, in several benign and malignant diseases, notably those characterized by extensive soft tissue calcification, Tc-99m MDP may be taken up by the tumor itself. We present a case of a stage IIIC psammoma-rich low-grade serous carcinoma of the ovary, whose identity and extent of disease were first suggested by Tc-99m MDP scintigraphy. The literature concerning this form of cancer, and the use of Tc-99m MDP bone scans to image soft tissue lesions, are reviewed.     

Combined bone marrow and gallium imaging. Differentiation of osteomyelitis and infarction in sickle hemoglobinopathy

The clinical records and scintigrams of patients with sickle hemoglobinopathy who underwent combined Tc-99m bone marrow imaging and Ga-67 imaging to differentiate osteomyelitis from bony infarction were reviewed. Of 18 paired examinations in 15 patients, osteomyelitis was diagnosed correctly in six cases; in all six, gallium uptake at the symptomatic site was incongruently increased relative to the bone marrow activity. Of the 12 episodes of infarction, 11 showed congruent activity on both Tc-99m and Ga-67 images. The remaining study was interpreted incorrectly as osteomyelitis due to incongruent Tc-99m and Ga-67 uptake. The use of sequential Tc-99m bone marrow and Ga-67 imaging is an effective means of distinguishing osteomyelitis from bony infarction in patients with sickle hemoglobinopathy.     

Comparison of bone scan and radiograph sensitivity in the detection of steroid-induced ischemic necrosis of bone

A prospective study of bone scanning for detection of ischemic necrosis of bone (INB) was performed in 36 patients (97% female, age range 16-36 yrs.) with systemic lupus erythematosis (SLE). Since the hips, knees, and shoulders are usually affected by INB in patients with SLE, 300 K converging collimator images of these joints were obtained on film and in digital format 2 to 3 hours after the injection of 20 mCi (740 MBq) of Tc-99m methylene diphosphonate. All patients underwent radiography of the joints, and 10 had intraosseous pressure determinations in the marrow space of affected joints (n = 31) for independent assessment of INB. Scans showed abnormally increased joint activity in 28 of the 36 patients. A total of 97 joints showed abnormalities, 19% in the hips, 34% in the knees, and 47% in the shoulders. Twenty-four of 27 joints with elevated bone marrow pressure (BMP) had abnormal scans (sensitivity = 89%), and scans were abnormal in 2 of 4 joints with normal pressures (specificity = 50%). The positive predictive value of the scans compared with BMP measurements was 92% (24/26). Eleven of 27 joints with abnormal BMP had abnormal radiographs, a sensitivity of 41%.     

Tc-99m depreotide SPECT demonstrates photon-deficiency in the thoracic vertebrae after adjunct radiation therapy of lung cancer: Correlation with MRI and bone scintigraphy

Fifteen months after right lobe lobectomy with adjunctive radiation therapy for squamous cell carcinoma, a patient 53-yr-old man underwent Tc-99m depreotide chest single photon emission tomography (SPECT). In addition to two focal areas of abnormally increased uptake in the right lung, the Tc-99m depreotide SPECT showed cold areas in the middle thoracic vertebrae. Photopenic areas in the 6th and 7th thoracic vertebrae were shown on a bone scintigraphy. T1 weighted magnetic resonance imaging (MRI) of the spine showed fatty replacement of the marrow and Schmorl's nodes involving the 5th to 11th thoracic vertebrae. The vertebrae are normally visualized in Tc-99m depreotide SPECT imaging study, and lung tumor is usually somatostatin receptor positive with demonstrable activity in the lung. Absent uptake in the vertebrae in the fatty replacement of the marrow and multiple and giant vertebral Schmorl's nodes in the correspondent vertebrae in MRI may reflect visualization of vertebrae due to Tc-99m depreotide localizing in the bone marrow. Of the three imaging modalities, MRI showed the widest areas of thoracic vertebral involvement. One should be aware that a cold lesion in the vertebrae on Tc-99m depreotide imaging study may result from irradiation and may indicate the presence of a benign lesion in the bone marrow.     

Technetium-99m DTPA aerosol and gallium scanning in acquired immune deficiency syndrome

In 11 non-smoking AIDS patients suspected of pneumocystis carinii pneumonia (PCP), the results of Tc-99m DTPA aerosol clearances, gallium scans, and arterial blood gases were compared with those of bronchoalveolar lavage (BAL). Nine patients had PCP. All had increased clearances five times higher than the normal (5.6 +/- 2.3% X min-1 vs 1.1 +/- 0.34% X min-1, N = 10, P less than 0.001), suggesting an increased alveolar permeability. Gallium scans were abnormal in six patients but normal or slightly abnormal in the three others. Four of these nine patients had normal chest x-rays. In two of these the gallium scan was abnormal, but in the two others, only the increased Tc-99m DTPA clearances showed evidence of lung disease. Two patients had normal BAL, with normal clearances and gallium scans. Four out of the nine patients with PCP were studied after treatment. Three recovered and had normal clearance and gallium scans. One still had PCP with increased clearance but normal gallium scan. Gallium scanning and Tc-99m DTPA clearance are useful for detecting lung disease in AIDS patients with suspected PCP and for prompting BAL when chest x-rays and PaO2 levels are normal. Due to its high sensitivity, a normal Tc-99m DTPA clearance could avoid BAL.     

Assessment of intra-arterial injected autologous bone marrow mononuclear cell distribution by radioactive labeling in acute ischemic stroke

OBJECTIVE: To evaluate the feasibility of monitoring the autologous mononuclear bone marrow (ABMMN) cells implanted into the brain after acute ischemic stroke by the technique of labeling with Tc-99m-HMPAO. CASE REPORT: A 37-year-old man presented with aphasia, right-side hypoesthesia, and right homonymous hemianopsia after an acute ischemic stroke of the left middle cerebral artery. He was included in an autologous bone marrow mononuclear cell-based therapy research protocol about the safety of intra-arterial autologous bone marrow mononuclear cell transplantation for acute ischemic stroke. Nine days after the stroke he received 3.0 x 10(7) ABMMN cells delivered into the left cerebral middle artery via a balloon catheter. Approximately 1% of these cells were labeled with 150 MBq (4 mCi) Tc-99m by incubation with hexamethylpropylene amine oxime (HMPAO). RESULTS: Brain perfusion images with Tc-99m ECD demonstrated hypoperfusion in the left temporal and parietal regions. The perfusion brain images were compared with tomographic views of the brain obtained 8 hours after ABMMN-labeled cell delivery, revealing intense accumulation of the ABMMN-labeled cells in the ipsilateral hemisphere. A whole-body scan was done and showed left brain, liver, and spleen uptake. CONCLUSIONS: Our results showed that Tc-99m HMPAO can be used to label ABMMN cells for in vivo cell visualization, and that brain SPECT imaging with labeled ABMMN cells is a feasible noninvasive method for studying the fate of transplanted cells in vivo. Additionally, our findings demonstrate the localization of these intra-arterially injected cells.