Dov Front

Gallium 67 imaging in monitoring lymphoma response to treatment

The value of gallium 67 (Ga) imaging in monitoring lymphoma response to treatment was assessed in 25 patients with Ga‐avid tumors and compared to body computed tomography (CT), chest radiographs, and palpation of tumor infiltrated peripheral lymph nodes. Ga imaging was negative in 95% (20/21) of the patients who were clinically considered to be in remission and in whom treatment was stopped. The disease did not recur during a follow‐up of 12 to 26 months in 15 patients. Six patients developed recurrence of the disease 3 to 12 months after treatment was stopped. In all six patients Ga imaging became positive again at the time of the appearance of active disease. In the group of patients in remission, CT was negative in 57% (11/19), chest x‐rays in 55% (6/11) and peripheral lymph nodes were palpated in none of the patients (13/13). In four patients that did not achieve remission after treatment, Ga scans were positive. Ga imaging appears useful in monitoring lymphoma response to treatment. This is probably because Ga imaging monitors tumor cell viability, whereas body CT and chest radiographs show the tumor mass, which may consist of fibrotic or necrotic tissue.

The role of Ga-67 scintigraphy in evaluating the results of therapy of lymphoma patients.

Gallium-67 scintigraphy using high-dose, modern equipment, and SPECT plays an important role in the evaluation of patients with lymphoma after treatment. Being a viability agent, taken up by lymphomatous, but not by necrotic or fibrotic tissue, it is used to assess the nature of a residual mass after treatment. Gallium also predicts disease-free survival and overall survival after treatment. It is used with high sensitivity and specificity for diagnosis of recurrence after a continuous clinical remission, which is achieved after successful treatment. A potential use for Gallium is in early evaluation, during treatment, of the rapidity of response. This evaluation determines early the effectiveness of therapy in the individual patient. After treatment Ga-67 scintigraphy appears to be superior to computed tomography and probably magnetic resonance imaging. It is used routinely in the management of patients with lymphoma.

An Evaluation of 99mTc-Labeled Red Blood Cell Scintigraphy for the Detection and Localization of Gastrointestinal Bleeding Sites

99mTechnetium-labeled red blood cell scintigraphy was performed upon 39 patients with clinical evidence for acute lower gastrointestinal bleeding from an unknown source. Seventeen of 39 patients (44%) had a scan became positive 6 or more h after injection, consistent with intermittent bleeding, in 8 of 17 patients (47%). In the 11 patients in whom the bleeding site was definitely identified by arteriography, surgery, or colonoscopy, scintigraphy correctly localized the bleeding site in 10 of 11 patients (91%). Four of 11 patients (36%) had an active bleeding site identified by arteriography. Ten of 17 patients (58%) with a positive scan required either gelfoam embolization (4 patients) or surgery (6 patients) to control the bleeding, whereas only 1 of 22 patients (5%) required surgery when the scan was negative. Six deaths occurred in the scan-positive patients compared with no deaths in the scan-negative patients. None of the 8 patients who had arteriography and no active bleeding site by scintigraphy had arteriographically demonstrable active bleeding. Scintigraphy provides a reliable noninvasive test to screen patients in whom arteriography is being considered to localize active bleeding sites. If the arteriogram is negative, the scintigraphic findings alone may guide the surgical or arteriographic intervention. In addition, scintigraphy identifies two patient populations which have considerably different morbidity and mortality.

Single-photon emission computed tomography quantitation of gallium citrate uptake for the differentiation of lymphoma from benign hilar uptake

PURPOSE To assess the role of quantitative gallium citrate (Ga 67) single-photon emission computed tomography (SPECT) in differentiating lymphoma from benign hilar uptake, concentrations of Ga 67 in 29 sites of documented lymphoma and in 75 benign lesions were compared. PATIENTS AND METHODS One hundred seven thoracic Ga 67 SPECT studies obtained in 101 consecutive lymphoma patients were reviewed. Fifty-nine studies detected Ga 67 uptake in the hilar and or mediastinal regions. Forty-eight studies showed no such abnormality. The concentration of Ga 67 in the thoracic lesions was measured using a quantitative SPECT technique and its nature was determined by correlation with computed tomographic (CT) scans and follow-up evaluation of the sites. RESULTS In 20 of 59 abnormal studies (34%), there was lymphoma in the hilar and or mediastinal regions. In the remaining 39 abnormal studies (66%), Ga 67 uptake was benign. There were 29 sites of lymphoma and 75 benign lesions. The concentration of Ga 67 in lymphoma was significantly higher than in benign hilar uptake (13.2 +/- 5.4 %ID/mL x 10(-3) v 5.6 +/- 1.5 % injected dose (ID)/mL x 10(-3); P < .001). A concentration value of 8.3 %ID/mL x 10(-3) was found to best separate lymphoma and benign uptake, with a sensitivity of 90%, a specificity of 93%, a positive predictive value of 84%, and a negative predictive value of 96%. CONCLUSION Lymphoma and benign hilar uptake differ significantly in their concentration of Ga 67. The present study shows that quantitative Ga-67 SPECT reliably differentiates lymphoma and benign uptake.

Utility of gallium-67 scintigraphy in low-grade non-Hodgkin's lymphoma.

PURPOSE Low-grade non-Hodgkins lymphoma (LGNHL) has traditionally been considered non-gallium-avid. The sensitivity of gallium 67 (67Ga) scintigraphy when using modern equipment and techniques in patients with LGNHL was investigated. MATERIALS AND METHODS Fifty-seven consecutive patients with LGNHL underwent 67Ga scintigraphy at initial presentation (n = 40), when tumor progression occurred during treatment (n = 3), and at suspected disease recurrence after continuous clinical remission (CCR) (n = 14). Planar and tomographic images were obtained with either a very large field-of-view or a dual-head digital camera. Of 45 patients with Ga-avid LGNHL, 30 underwent 93 follow-up scans (one to six studies per patient). Scan findings were correlated with clinical and computed tomographic (CT) findings and with patient outcomes. RESULTS 67Ga scintigraphy was positive in 45 of 57 patients (sensitivity, 79%) and in 113 of 164 disease sites (sensitivity, 69%). The sensitivity was higher in the more common types of LGNHL: follicular, predominantly small cleaved cell (FSC), and follicular, mixed small cleaved and large cell (FM) (84% and 91% in patients and 72% and 71% in disease sites, respectively). Sensitivity was lower in patients with mucosa-associated lymphoid tissue lymphoma (MALT) and small lymphocytic lymphoma (SL). Among 28 patients with disease recurrence after CCR (14 with and 14 without baseline studies), 67Ga scan was positive in 25, for a sensitivity of 89% for detection of disease recurrence. CONCLUSION When modern technology is used, 67Ga scintigraphy has good sensitivity in patients with LGNHL. It therefore can be used to monitor response to therapy and to provide early detection of disease recurrence in these patients.

A practical SPECT technique for quantitation of drug delivery to human tumors and organ absorbed radiation dose

A practical quantitative single photon emission computed tomographic (SPECT) technique based on an empirical threshold analysis permits accurate measurements in humans of drug delivery and absorbed radiation dose. The limits of the method have been explored using a wide range of phantom volumes, concentrations, and target-to-nontarget ratios. A threshold of 43% was found to give the best results using volumes of 30 to 3,800 cc. An excellent correlation (r = .99 with a standard error of estimate [SEE] of 41 cc) was found between SPECT measured volumes and actual phantom volumes. A similarly high correlation (r = .98, SEE = 260 counts/voxel) was found in 77 measurements of concentrations between 0.01 and 3.6 microCi/cc. There was a direct relationship between the target-to-nontarget ratio of phantoms and the accuracy of volume measurements. The technique has been validated by an excellent in vivo/in vitro correlation of uptake in human tumors. The tumor cumulative concentration and tumor-to-blood ratio were used for assessment of drug delivery. In vivo quantitative measurements of the pharmacokinetics of technetium-99m (99mTc) glucoheptonate, cobalt-57 (57Co) bleomycin and platinum-195m (195mPt) cisplatin in human tumors in vivo indicates that, in contrast with tumor models in animals, there is a marked variability in drug delivery even in tumors with the same histology. Future development of labeled drugs should make it possible to use quantitative SPECT for predicting tumor response to therapy and for tailoring chemotherapy for the individual patient under treatment. SPECT quantitation of organ concentration was used for Medical Internal Radiation Dose committee (MIRD) calculations of organ absorbed radiation dose from 99mTc-labeled RBCs. Excellent in vivo/in vitro correlations were obtained between SPECT measured concentrations of blood radioactivity in the heart and in vitro measurements of blood samples. The possibilities and limitations of this technique are discussed and its use for in vivo measurement in humans of absorbed radiation dose from radiopharmaceuticals is suggested.

The continuing clinical role of gallium 67 scintigraphy in the age of receptor imaging

Gallium 67 scintigraphy is useful clinically for assessment of tumor viability after treatment of Hodgkins and nonHodgkins lymphoma. Because more than 50% of the patients with complete response have a residual mass after treatment, computed tomography is not a good test to determine if a patient has reached a complete response. 67Ga scintigraphy, on the other hand, has a sensitivity of 76% to 100% and specificity of 75% to 96% to determine if a residual mass is a residual cancer or made up only of fibrosis and necrosis. Early diagnosis of recurrence is important in order to start therapy when the tumor can, potentially, still be controlled. The sensitivity of 67Ga for diagnosis of recurrence is 95% and the specificity 89%. Scintigraphy has been shown to diagnose recurrence sometimes months before other tests. 67Ga scintigraphy also has the potential to separate rapid from slow responders during therapy. Even when it has been known for many years, 67Ga has proved recently to be a useful test in assessing lymphoma patients after treatment.

Chronic familial hyperphosphatasemia.

Two siblings displaying macrocrania and multiple skeletal deformities, as well as cardiomegaly, had high levels of serum alkaline phosphatase and markedly increased urinary hydroxyproline excretion. The radiological findings of chronic familial hyperphosphatasemia, which are typical of a rare bone-remodeling disease, are presented. Scintigraphy disclosed intense uptake of the radionuclide by the skeletons of both patients. This finding, considered to be related to abnormal collagen metabolism, can be used in the diagnosis and assessment of skeletal involvement in such patients.

Clinical pretreatment risk factors and Ga-67 scintigraphy early during treatment for prediction of outcome of patients with aggressive non-Hodgkin lymphoma

Clinical pretreatment risk factors indicate the severity of disease in patients with aggressive non‐Hodgkin lymphoma (NHL). Ga‐67 scintigraphy during treatment is an early indicator of treatment‐related features of lymphoma cells. The ability of risk factors and Ga‐67 to predict disease outcome was compared in 139 patients with aggressive NHL.

Stress fractures and bone pain: are they closely associated?

The relationship between bone pain and stress fractures diagnosed by bone scintigraphy was investigated in military recruits during active training. In three patients pain appeared in the site of abnormal uptake 7-14 days after the bone scan in a previously asymptomatic site. One hundred and twenty-four sites of stress fractures were found in 64 patients; 32 (26 per cent) were asymptomatic. In 38 patients (59 per cent) there were multiple stress fractures; 32 (33 per cent) had asymptomatic stress fractures. Fifty-three per cent of the regions with abnormal uptake in the femur were painless, compared with 17 per cent in the tibia. The necessity for imaging all bones susceptible to stress fractures, even when asymptomatic, is stressed. It is suggested that diagnosis of stress fracture should be made when typical abnormal uptake appears on scintigraphy. Bone pain in such cases may be delayed.