The value of gallium-67 and thallium-201 whole-body and single-photon emission tomography images in dialysis-related beta 2-microglobulin amyloid

The aim of this study was to investigate the value of gallium-67 and thallium-201 whole-body and single-photon emission tomography (SPET) images in long-term dialysis patients in whom dialysis-related beta 2-microglobulin amyloid (beta 2-MA) was clinically suspected. Twenty-three patients who had received dialysis for at least 10 years were included in the study. A technetium-99m methylene diphosphonate (MDP) whole-body scan was performed in all of the patients. If there was any MDP accumulation in the articular and/or peri-articular region, 67Ga and 201Tl whole-body and SPET images were then acquired. If any 67Ga and/or 201Tl uptake was observed, a CT-guided biopsy was done. In those patients who had articular and/or peri-articular uptake of 99mTc MDP, 67Ga and/or 201Tl and who were pathologically proven to have beta 2-MA, 99mTc MDP, 67Ga and 201Tl whole-body scans and SPET were carried out again, both 3 months and 1 year after initiation of treatment. This served to evaluate the therapeutic effect and allowed comparison with the clinical findings. Of the 23 patients, eight had abnormal 99mTc MDP uptake. Among these eight, six had intense 99mTc MDP, 67Ga and 201Tl uptake in the articular and peri-articular regions before medication. Three months after the start of treatment, there were very marked decreases in uptake on both the 67Ga and 201Tl scans but less obvious changes in uptake of 99mTc-MDP. In comparison with the other clinical manifestations such as limitation in range of motion, the more the painful disability improved, the less was the uptake on both 67Ga and 201Tl scans. There were virtually no differences in uptake pattern between the three scans of each radiopharmaceutical obtained for each patient in both 3 months and 1 year after initial of treatment. It is concluded that 99mTc-MDP whole-body bone scan can both detect active and pre-existing inactive deposits of beta 2-MA. 67Ga and 201Tl scans are helpful to differentiate active from inactive deposits of beta 2-MA and to evaluate the therapeutic effect on these patients. SPET images are usually needed to distinguish articular and periarticular lesions from bone lesions.     

Hematogenous pyogenic vertebral osteomyelitis: diagnostic value of radionuclide bone imaging

Hematogenous pyogenic vertebral osteomyelitis (HPVO) continues to be a diagnostic problem for clinicians due to nonspecific presentation of the disease (1,2). We reviewed our experience of the last 10 years to determine the diagnostic usefulness of radionuclide bone studies in this disease. We found 15 patients whose primary diagnosis was HPVO. Of the 15 patients, 12 had [99mTc]MDP bone scans which were all positive. Five of the 12 patients had positive [67Ga]citrate scans and one patient with chronic active HPVO had negative 67Ga and [111In]WBC bone images. At the same time, three patients' spine x-rays and one patient's CT scan of the vertebra were normal. Additionally, in three patients spine x-rays were interpreted as consistent with degenerative joint disease that contributed to the delay of the diagnosis. We conclude that when HPVO is suspected an abnormal [99mTc]MDP bone image increases the probability of the disease, even if the x-rays and CT scans of the spine are normal. An abnormal 67Ga image following an abnormal 99mTc bone image increases the specificity of the diagnosis. Normal [99mTc]MDP and [67Ga]citrate bone images of the vertebra virtually exclude the diagnosis of HPVO.     

Reliability of gallium brain scanning in the detection and differentiation of central nervous system lesions.

Both 99mTc-pertechnetate and 67Ga-citrate brain scans were performed in 93 patients with cerebral neoplasms and in 70 others with cerebral infarction or hemorrhage. Tumor detection was clearly better with 67Ga(96%) than with 99mTc(85%). Cerebral infarctions consistently either failed to concentrate 67Ga(67%) of revealed a much lower concentration than the 99mTc study (27%). In 6% of the infarction patients, gallium and technetium scans were equivalent.     

Gallium-67 citrate in cerebral infarction.

Cerebral scans were obtained on 30 "stroke" patients first with 99mTc pertechnetate and subsequently with 67Ga citrate. Of the 26 patients with abnormal 99mTc static scans, 17 (65%) showed the same abnormality in gallium citrate scans also. In 4 patients with positive technetium flow studies but negative static scans, no abnormality was seen in the scans obtained after gallium citrate injection. In none of the patients was the relative concentration of radioactivity in the lesion greater in the gallium image than in the technetium image. This study proves the nonspecificity of gallium citrate and thus its inability to differentiate cerebral tumor from cerebral infarction just on the basis of localization of gallium.     

Thallium-201 brain tumor imaging: a comparative study with pathologic correlation

In patients with gliomas who were stable or improving, we noted a disparity between clinical status and computed tomography (CT) brain scan results. To elucidate this finding, 29 patients were sequentially scanned with 2.0 mCi of 201Tl (5-30 min), 20 mCi [99mTc]gluceptate (GH) (3-4 hr) and 7-10 mCi 67Ga (48-72 hr). A total of 198 images were obtained. A set of three scans at a midpoint in follow up was selected for analysis. Seven patients who died had neuropathologic data available; brain sections were reconstructed to match radionuclide views without knowledge of image results. In the seven patients with autopsy data, 201Tl offered the most accurate correlation with viable tumor. Gallium-67 gave similar results in patients not receiving steroids. Technetium-99m GH scans could not allow differentiation between tumor, necrosis, and edema. Similarly, the CT scan could not routinely differentiate between fibrotic, nonfibrotic, necrotic, and neoplastic tissue. In the 22 patients without autopsy data, 201Tl scans commonly showed smaller and more focal abnormal uptake when compared with [99mTc]GH and 67Ga scans. Thallium-201 scans more accurately reflect viable tumor burden than other radionuclide studies of primary brain tumors, are minimally affected by concomitant steroid administration, can be performed immediately following tracer administration, and complement the anatomic data obtained from CT scans.     

Comparative uptake of 67Ga and 99mTc MDP in rabbits with a benign noninfected bone lesion (fracture)

Mid-shaft fractures of the radius and ulna were produced in 3 to 4 kg New Zealand white rabbits and quantitative uptake of 99mTc MDP and 67Ga determined at 11, 18, 25, 32, 51, and 78 days following fracture. Two hundred microCi of 67Ga was administered 24 hours prior to sacrifice and 1.5 mCi 99mTc MDP 2 hours prior to sacrifice. Specific activity ratios (SARs) were determined between fracture and control sides for bone, muscle and skin. SARs for bone were surprisingly similar for 99mTc MDP and 67Ga, reaching peak values of 6.07 +/- 0.64 (99mTc 18 days); 6.58 +/- 0.90 (67Ga 32 days), subsequently decreasing to minimum values at 78 days postfracture (99mTc MDP 2.25 +/- 0.14; 67Ga 2.18 +/- 0.08). There was no statistically significant difference in SAR for 99mTc MDP vs. 67Ga in bone at any time after fracture. Whole sections of limb were resected on selected animals and activity ratios determined for these sections as a function of the contribution of activity from the various tissues in the volume of interest. Total activity ratios of 67Ga were lower than bone SARs as a result of the contribution of activity from muscle and skin. Thus the apparent lower activity ratios noted on 67Ga images compared with 99mTc MDP images in this fracture model were not due to differences in bone SARs but rather due to the higher soft tissue background activity contribution in the 67Ga images.     

Uptake of myocardial imaging agents by rejecting and nonrejecting cardiac transplants. A comparative clinical study of thallium-201, technetium-99m, and gallium-67

To study the scintigraphic detectability of cardiac rejection, we performed 135 planar myocardial scans ([99mTc]pyrophosphate, 85; 201Tl, 36; 67Ga, 14) together with endomyocardial biopsies in ten patients for a (mean) 17-mo postoperative period. Specificity of each agent exceeded 89%. Technetium-99m pyrophosphate showed results that significantly correlated with the severity of rejection (p = 0.03), as shown by biopsy, but neither 201Tl nor 67Ga did so (p = 0.63 and 0.81, respectively). Technetium-99m pyrophosphate showed better diagnostic accuracy (85%) than 201Tl (69%) and 67Ga (64%). Technetium-99m pyrophosphate also showed higher negative predictive value (91%) than thallium (76%) and gallium (69%). Thus, a normal 99mTc pyrophosphate scan was usually associated with absence of cardiac rejection. However, all three agents showed unacceptably poor sensitivity (0% to 30%) and thus were not useful as a screening test for cardiac rejection, even when the same agent was used serially in imaging a given patient.     

Acute osteomyelitis in children: combined Tc-99m and Ga-67 imaging

This retrospective study was done to determine the value of combined bone (technetium-99m methylene-diphosphonate) and gallium-67 citrate imaging in selected children with complicated clinical situations. Thirty-one children were evaluated for suspected osteomyelitis by bone scan followed within 4 days by a gallium scan. These 31 children represented a subpopulation in whom the Tc-99m scan is known to be potentially unreliable in diagnosing acute osteomyelitis. Eight children had acute osteomyelitis by strict criteria, while 23 did not. The bone scan successfully identified five of the eight with osteomyelitis but was positive in ten of the other 23. The gallium scan correctly identified all eight with osteomyelitis but was positive in seven of the other 23. The gallium scan was significantly less specific when the suspected lesion was in the extremities compared with central locations; causes of false-positive gallium scans included fracture and juvenile rheumatoid arthritis. Combined gallium and bone scanning increased accuracy of the scintigraphic diagnosis of acute osteomyelitis. Both tests may, however, be abnormal in conditions other than osteomyelitis. These findings emphasize the importance of correlating all imaging studies in detection of osteomyelitis.     

The value of gallium-67 and thallium-201 whole-body and single-photon emission tomography images in dialysis-related β2-microglobulin amyloid

The aim of this study was to investigate the value of gallium-67 and thallium-201 whole-body and single-photon emission tomography (SPET) images in long-term dialysis patients in whom dialysis-related β₂-microglobulin amyloid (β₂-MA) was clinically suspected. Twenty-three patients who had received dialysis for at least 10 years were included in the study. A technetium-99m methylene diphosphonate (MDP) whole-body scan was performed in all of the patients. If there was any MDP accumulation in the articular and/or peri-articular region, ⁶⁷Ga and ²⁰¹Tl whole-body and SPET images were then acquired. If any ⁶⁷Ga and/or ²⁰¹Tl uptake was observed, a CT-guided biopsy was done. In those patients who had articular and/or peri-articular uptake of ^99mTc MDP, ⁶⁷Ga and/or ²⁰¹Tl and who were pathologically proven to have β₂-MA, ^99mTc MDP, ⁶⁷Ga and ²⁰¹Tl whole-body scans and SPET were carried out again, both 3 months and 1 year after initiation of treatment. This served to evaluate the therapeutic effect and allowed comparison with the clinical findings. Of the 23 patients, eight had abnormal ^99mTc MDP uptake. Among these eight, six had intense ^99mTc MDP, ⁶⁷Ga and ²⁰¹Tl uptake in the articular and peri-articular regions before medication. Three months after the start of treatment, there were very marked decreases in uptake on both the ⁶⁷Ga and ²⁰¹Tl scans but less obvious changes in uptake of ^99mTc-MDP. In comparison with the other clinical manifestations such as limitation in range of motion, the more the painful disability improved, the less was the uptake on both ⁶⁷Ga and ²⁰¹Tl scans. There were virtually no differences in uptake pattern between the three scans of each radiopharmaceutical obtained for each patient in both 3 months and 1 year after initial of treatment. It is concluded that ^99mTc-MDP whole-body bone scan can both detect active and pre-existing inactive deposits of β₂-MA. ⁶⁷Ga and ²⁰¹Tl scans are helpful to differentiate active from inactive deposits of β₂-MA and to evaluate the therapeutic effect on these patients. SPET images are usually needed to distinguish articular and peri-articular lesions from bone lesions. Received 19 May and in revised form 9 August 1999     

Nuclear medicine studies in evaluation of skeletal lesions in children with histiocytosis X

Radiographs were compared with 99mTc scans of the bones and bone marrow as well as 67Ga-citrate scans to evaluate their sensitivity in identifying skeletal lesions in 21 children with histiocytosis X. Seven of 20 bone scans were completely normal in patients with extensive radiographic evidence of skeletal disease. In only one patient were bone scan changes demonstrated prior to radiographic abnormalities. None of the lesions was "cold" on the bone scans. 99mTc-sulfur colloid bone marrow scans and 67Ga-citrate whole-body scans were not valuable. Radiographic survey of the skeleton should be the primary diagnostic test employed in patients with histiocytosis X who have suspected skeletal lesions. Bone scans should be obtained only when the radiographs are normal or equivocal.     

Comparison of technetium-99m-HM-PAO leukocytes with indium-111-oxine leukocytes for localizing intraabdominal sepsis

Technetium-99m-HM-PAO [( 99mTc]HM-PAO) leukocyte and indium-111-oxine (111In-oxine) leukocyte scanning were carried out simultaneously in 41 patients at 4 hr and 24 hr after reinjection to determine whether the 4-hr 99mTc scan could replace the 24-hr 111In scan for detecting intraabdominal sepsis. Abdominal infection was confirmed in 12 cases. The 4-hr 99Tc-leukocyte scan, the 4-hr 111In-leukocyte scan, and the 24-hr 111In-leukocyte scan yielded a sensitivity of 100%, 67%, and 100%, respectively, and a specificity of 62%, 90%, and 86%, respectively. The 24-hr 99mTc-leukocyte scan also produced a sensitivity of 100%, but it was falsely positive in all 29 cases without infection due to physiologic bowel uptake. False-positive 4-hr 99mTc-leukocyte scans were also produced by physiologic bowel uptake in seven cases all of whom had true-negative 4-hr and 24-hr 111In-leukocyte scans. Because of the high incidence of false-positive 4-hr [99mTc]HM-PAO leukocyte scans, it was concluded that they could not replace 24-hr 111In-leukocyte scans for detecting intraabdominal sepsis, and that serial 99mTc leukocyte scans starting earlier than 4 hr after reinjection must be evaluated.     

Prognostic impact of pre-transplantation computed tomography and 67gallium scanning in chemosensitive diffuse large B cell lymphoma patients undergoing hematopoietic stem-cell transplantation

OBJECTIVE: In the present study, we evaluated computed tomography (CT) and (67)gallium scanning ((67)Ga scan) pre-transplant as prognostic factors for overall survival (OS) and event-free survival (EFS) in patients with diffuse large B cell lymphoma, undergoing high-dose chemotherapy and stem-cell transplantation. PATIENTS AND METHODS: Forty-two patients were included. Of these, 9 (21%) had both positive CT and (67)Ga scans, 17 (41%) negative results with both techniques, and 16 (38%) positive CT/negative (67)Ga scan. Whole-body planar imaging and single-photon emission computed tomography (SPECT) were performed 72 h after an intravenous administration of (67)Ga citrate measuring between 7 mCi and 10 mCi (259-370 MBq). RESULTS: Patients with positive CT/positive (67)Ga scan had a significantly worse EFS and OS at 5 years than those with negative (67)Ga scan regardless of whether it was associated with a positive or a negative CT scan (29% and 16% vs. 81% and 93% vs. 88% and 100%, respectively, P < 0.001). After a median follow-up of 43 months (range 4-130 months), no differences were observed between patients with negative CT/negative (67)Ga scan and those with positive CT/negative (67)Ga scan, with an EFS and OS at 5 years of 88% versus 81% and 100% versus 93%, respectively. In multivariate analysis, the presence of a pre-transplant positive CT/(67)Ga scans adversely influenced both EFS and OS [HR 8, 95% confidence interval (CI) (1.4-38), P = 0.03 and HR 2; 95% CI (1.3-8), P = 0.02, respectively]. CONCLUSIONS: (67)Ga scan helps to identify, in the pre-transplant evaluation, two groups with a different outcome: one group of patients with positive CT and negative (67)Ga scans pre-transplant, who showed a favorable outcome with a low rate of relapse, and the other group of patients with both positive CT and (67)Ga scans pre-transplant, who showed a poor prognosis and did not benefit from autologous stem-cell transplantation. They should have been offered other therapeutic strategies.     

The role of 99mTc(V)-DMSA scan as compared to 99mTc-MDP and CT scans in imaging the primary tumor and metastases of osteosarcoma

The oncophilic complex of technetium-99m labeled pentavalent dimercaptosuccinic acid (99mTc(V)-DMSA) has been successfully used for the detection of primary and metastatic medullary thyroid cancer and for imaging various soft tissue tumors like lung, brain and prostate cancer. In this article, the role of 99mTc(V)-DMSA in the diagnosis of the primary tumor and metastases of osteosarcoma patients as compared to the 99mTc-MDP scan and the CT scan was studied. Twenty-eight patients with bone disease were referred to the Nuclear Medicine Department of Saint Savas Oncology Hospital in Athens from the Orthopedics Department of the same Hospital. From them, 18 (Group A) had osteosarcoma, 7 (Group B) osteomyelitis and 3 (Group C) bone fractures. The final diagnosis was made after fine needle aspiration biopsy. All patients were subjected to the 99mTc(V)-DMSA scan, the standard bone scan (99mTc-MDP) and CT scan. Group A patients showed a selective uptake of 99mTc(V)-DMSA in the primary tumor region. No abnormal 99mTc(V)-DMSA uptake was observed in the patients of Groups B and C. The 99mTc(V)-DMSA scan was found to be superior to the 99mTc-MDP and the CT scans in identifying metastases of osteosarcoma. Sensitivity was 100%, 86% and 98% respectively.     

Technetium-99m-DTPA aerosol and gallium-67 scanning in pulmonary complications of human immunodeficiency virus infection.

We retrospectively compared the results of 67Ga chest scans and 99mTc-DTPA aerosol clearance measurements with those of fiberoptic bronchoscopy in 88 patients infected with the human immunodeficiency virus. Of 100 investigations, a pulmonary infection was diagnosed in 39, mainly Pneumocystis carinii pneumonia and a noninfectious disorder was found in 42, mainly Kaposi's sarcoma and lymphocytic alveolitis. Gallium scans and DTPA clearance were abnormal respectively in 74% and 92% of infectious complications, and in 12% and 60% of noninfectious disorders. In 10 cases, DTPA clearance was accelerated, while chest x-ray, arterial blood gases and even gallium scanning were normal. A value of DTPA clearance greater than 4.5%.min-1 was both sensitive and specific for the diagnosis of Pneumocystis carinii pneumonia. The gallium scan was always normal in bronchopulmonary Kaposi's sarcoma. We conclude that in symptomatic patients: (1) DTPA clearance measurements are useful for detecting lung disease when chest x-ray and/or PaO2 are normal and (2) a gallium scan is indicated to distinguish progressive Kaposi's sarcoma from a superimposed second process when radiological abnormalities of pulmonary Kaposi's sarcoma are present.     

Detection of hepatoma in liver cirrhosis.

The analogic liver scintigram using 99mTc sulfur colloid in cirrhotic patients does not permit determination of the nature of the areas of decreased uptake. Scintigrams with 67Ga citrate generally show increased activity in cases of hepatoma. In some cases, however, 67Ga citrate is less concentrated in neoplasic tissue, and it is not possible to detect a tumoral lesion in a cirrhotic liver. This is why we used double isotope scintigraphies with 67Ga citrate and 99mTc sulfur colloid, with digital subtraction, after simultaneous recording of 99mTc and 67Ga data on magnetic tape by means of an interface. In our series of 22 patients, the comparison of the results obtained by this double isotope technique with histology showed no false positive in substraction scintigrams. There was one false negative because of the lack of significance in the subtracted image for one of the six patients with cancer of the liver. For three of the six patients with hepatoma, the gallium scintigram showed an increased uptake in the tumor area. For the three other cases, the gallium uptake was equilibrated throughout the liver scintigraphy. It was therefore in cases where the gallium scintigram showed no increased activity that the subtraction technique was of greatest value, for it permitted the diagnosis of hepatoma in two cases.     

Hodgkin's disease: prognostic role of gallium scintigraphy after chemotherapy.

Evaluation of the response to therapy is important for optimal selection of treatment strategy in patients with Hodgkin's disease (HD). Refractory disease requires intensive high-dose chemotherapy, whereas unnecessary treatment should be avoided in patients in complete remission. The purpose of this study was to evaluate the contribution of gallium-67 scintigraphy in predicting the clinical outcome in patients with HD and mediastinal involvement on the basis of scan results at the end of chemotherapy. Seventy-four patients with HD and mediastinal involvement were retrospectively investigated with 67Ga scintigraphy 72 h after injection of 220 MBq 67Ga citrate (planar and single-photon emission tomographic studies) following the completion of chemotherapy. At the same time, they all underwent computed tomography (CT). Patients were followed up for an average of 63 months (range 28-124 months). The disease status was newly diagnosed disease in 64 of the patients and relapse in 10. Systemic symptoms were absent (A) in 34 cases and present (B) in 40 cases. Forty-one patients had stage I or II disease and 33 patients had stage III or IV disease. Twenty-two patients had bulky disease on initial diagnosis. At the end of chemotherapy, all 74 patients showed regression of the mass by more than 50% (50%-100%) on CT. Patients were divided into two groups according to the positivity or negativity of the gallium scan after chemotherapy: 61 patients had negative and 13 patients had positive gallium scans. In the gallium-negative group, 19.7% of the patients relapsed and 91.8% were alive at the end of the follow-up. Relapse occurred in 20% of the patients with residual mass and in 19.6% of the patients without residual mass. In the gallium-positive group, 84.6% of the patients had recurrent disease and 61.5% were alive after intensive chemotherapy. There was a statistically significant difference in overall survival between patients with positive and patients with negative gallium results (P=0.0034). Disease-free survival differed significantly between patients with positive and patients with negative gallium scans at the end of chemotherapy (P<0.0001). The relative risk of death was 5.2 and the relative risk of relapse was 11.3 for patients with positive gallium scans, in comparison to those with negative gallium scans. The positive and negative predictive values for predicting relapse were 85% and 87%, respectively. It is concluded that even if gallium scan is performed at the end of chemotherapy, it can predict outcome. Alternative therapy may be required on the basis of gallium scan results obtained after treatment.     

Hodgkin's disease: prognostic role of gallium scintigraphy after chemotherapy

Evaluation of the response to therapy is important for optimal selection of treatment strategy in patients with Hodgkin's disease (HD). Refractory disease requires intensive high-dose chemotherapy, whereas unnecessary treatment should be avoided in patients in complete remission. The purpose of this study was to evaluate the contribution of gallium-67 scintigraphy in predicting the clinical outcome in patients with HD and mediastinal involvement on the basis of scan results at the end of chemotherapy. Seventy-four patients with HD and mediastinal involvement were retrospectively investigated with ⁶⁷Ga scintigraphy 72 h after injection of 220 MBq ⁶⁷Ga citrate (planar and single-photon emission tomographic studies) following the completion of chemotherapy. At the same time, they all underwent computed tomography (CT). Patients were followed up for an average of 63 months (range 28-124 months). The disease status was newly diagnosed disease in 64 of the patients and relapse in 10. Systemic symptoms were absent (A) in 34 cases and present (B) in 40 cases. Forty-one patients had stage I or II disease and 33 patients had stage III or IV disease. Twenty-two patients had bulky disease on initial diagnosis. At the end of chemotherapy, all 74 patients showed regression of the mass by more than 50% (50%-100%) on CT. Patients were divided into two groups according to the positivity or negativity of the gallium scan after chemotherapy: 61 patients had negative and 13 patients had positive gallium scans. In the gallium-negative group, 19.7% of the patients relapsed and 91.8% were alive at the end of the follow-up. Relapse occurred in 20% of the patients with residual mass and in 19.6% of the patients without residual mass. In the gallium-positive group, 84.6% of the patients had recurrent disease and 61.5% were alive after intensive chemotherapy. There was a statistically significant difference in overall survival between patients with positive and patients with negative gallium results (P=0.0034). Disease-free survival differed significantly between patients with positive and patients with negative gallium scans at the end of chemotherapy (P<0.0001). The relative risk of death was 5.2 and the relative risk of relapse was 11.3 for patients with positive gallium scans, in comparison to those with negative gallium scans. The positive and negative predictive values for predicting relapse were 85% and 87%, respectively. It is concluded that even if gallium scan is performed at the end of chemotherapy, it can predict outcome. Alternative therapy may be required on the basis of gallium scan results obtained after treatment.     

Evaluation of cold areas on the thyroid scan with 67Ga-citrate.

Cold areas on 131I or 99mTc thyroid scans were re-evaluated using 67Ga-citrate in 134 patients. In 62 patients surgical specimens were obtained for histologic studies. Of 46 benign lesions, all had negative 67Ga scans, and 67Ga scans in 5 of the 16 lesions judged to be malignant were positive. It was thought that the sensitivity of the method did not warrant its use for routine screening in evaluations of malignancy of thyroid nodules.     

Complications of fractures and their healing

The role of nuclear medicine studies in diagnosing late complications of fractures is described. Static bone scintigraphy is not helpful in predicting delayed or non-union of fractures. Several investigators have developed simple formulae comparing uptake in fracture site with adjacent or contralateral normal bone and described criteria that will predict problems with healing. These types of tests should only be used in patients who are at risk for delayed union. The scintigraphic diagnosis of infection complicating a fracture is difficult. Bone scintigraphy alone is not useful and combined 67Ga/99mTc MDP scanning has been disappointing. Most published series support the role in 111In WBC in this situation, but not all cases are correctly diagnosed. 111In (Chloride) cannot differentiate an infected from a delayed-healing fracture. Bone scintigraphy has a significant role in determining whether a bone graft is viable or not. Reflex sympathetic dystrophy is a rare complication of a fracture; it can be diagnosed by increased periarticular uptake on bone scan in all the joints of the affected part. Bone scintigraphy, especially when done with SPECT, is a very sensitive test for the diagnosis of avascular necrosis (AVN).     

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.