Radiation pneumonitis in patients with lung and mediastinal tumours: a retrospective study of risk factors focused on pulmonary emphysema.

OBJECTIVES: To evaluate the impact of pulmonary emphysema (PE) on the incidence and severity of radiation pneumonitis (RP) in patients with lung and mediastinal tumours. METHODS: 92 patients were enrolled. Involved-field radiation therapy (non-small cell carcinoma or mediastinal tumours in 69 patients; median 70 Gy) and accelerated hyperfractionation (limited disease small cell carcinoma in 23 patients; median 45 Gy) were performed. Common Terminology Criteria for Adverse Events v.3.0 was used to evaluate RP and the relationship with the percentage of pulmonary volume irradiated to >20 Gy (V20) and PE. PE was diagnosed by the presence of low-attenuation areas (LAAs) on CT scans and was classified into Grades 0-4 according to the extent of the LAAs. RESULTS: The median follow-up time was 16 months. The 6-month cumulative incidence of RP at Grade 3 or greater was 7.7% and 34.1% in patients with a V20 of <25% and ≥25%, respectively (p=0.017). In patients with PE Grades 0, 1, 2 and 3 or greater, the incidence of RP was 16.5%, 9.1%, 8.6% and 54.0%, respectively. As the PE Grade increased, the incidence of RP also increased significantly. CONCLUSION: The incidence and severity of RP are significantly higher in patients with a high V20 value as well as in those with severe PE.

11C-acetate PET in the evaluation of brain glioma: comparison with 11C-methionine and 18F-FDG-PET.

PURPOSE: The aim of the study is to retrospectively investigate the usefulness of 11C-acetate (ACE)-positron emission tomography (PET) for evaluation of brain glioma, in comparison with 11C-methionine (MET) and 2-deoxy-2-18F-fluoro-D-glucose (FDG). PROCEDURES: Fifteen patients with brain glioma referred to initial diagnosis were examined with ACE, MET, and FDG-PET. Five patients had low-grade gliomas (grade II), three had anaplastic astrocytomas (grade III), and seven had glioblastomas (grade IV). PET results were evaluated by visual and semiquantitative analysis. For semiquantitative analysis, the standardized uptake value (SUV) and tumor to contralateral normal gray matter (T/N) ratio were calculated. The sensitivity for detection of high-grade gliomas was calculated using visual analysis. RESULTS: Sensitivities of ACE, MET, and FDG were 90%, 100%, and 40%, respectively. ACE and MET T/N ratios were significantly higher than that of FDG. ACE and FDG SUV in high-grade gliomas were significantly higher than that in low-grade gliomas. No significant differences were observed using MET. CONCLUSIONS: ACE PET is a potentially useful radiotracer for detecting brain gliomas and differentiating high-grade gliomas.

Interbreath-hold reproducibility of lung tumour position and reduction of the internal target volume using a voluntary breath-hold method with spirometer during stereotactic radiotherapy for lung tumours.

The purpose of this study was to evaluate the interbreath-hold reproducibility of the tumour (gross tumour volume, GTV) position and relative reduction of the internal target volume (ITV) using a voluntary breath-hold method with a spirometer in a clinical setting of stereotactic radiotherapy (SRT) for lung tumours 11 patients with 14 lung tumours were enrolled in this study. CT scans were performed once at the free breathing phase and five times at the breath holding phase before the first treatment day. Patients held their breath at the end-expiration phase under spirometer-based monitoring. All GTVs were delineated by a physician and the GTV centroid was calculated automatically. To evaluate the interbreath-hold reproducibility of the tumour position, we measured the distance of three dimensions (craniocaudal, CC; left-right, LR; anteroposterior, AP) and vectors between the GTV centroid and bony landmark. The reproducibility was defined as the average of the differences between the GTV centroid and bony landmark from the second to fifth CT scans with regard to that from the first CT scans. We also evaluated the relative reduction of ITV between the free breathing and breath-holding phase. The interbreath-hold reproducibility of the tumour position was 1.3+/-1.3 mm, 1.4+/-1.8 mm, 2.1+/-1.6 mm and 3.3+/-2.2 mm in CC, LR and AP directions and vectors, respectively. ITV at the breath-holding phase was significantly smaller than that at the free breathing phase (P<0.01). In conclusion, the voluntary breath-hold method with a spirometer is feasible, with relatively good reproducibility of the tumour position for SRT in the clinical setting.

Birth of mice after in vitro fertilization using C57BL/6 sperm transported within epididymides at refrigerated temperatures.

The transportation of cryopreserved spermatozoa is an economical, efficient, and safe method for the distribution of mouse strains from one facility to another. However, spermatozoa from some strains, including C57BL/6 (B6), are very sensitive to freezing and thawing and frequently fail to fertilize eggs by conventional in vitro fertilization methods at the recipient mouse facility. Since many genetically engineered mice have the B6 genetic background, this sensitivity poses a major obstacle to studies of mouse genetics. We investigated the feasibility of transporting spermatozoa within epididymides under non-freezing conditions. First, we examined the interval that B6 and B6D2F1 (BDF1) spermatozoa retained their ability to fertilize when stored within epididymides at low temperatures (5 degrees C or 7 degrees C). Fertilization rates were >50%, irrespective of the spermatozoa used, when epididymides were stored for 3d at 7 degrees C. B6 spermatozoa, but not BDF1 sperm, had better retention of fertilizing ability at 7 degrees C versus 5 degrees C. We then transported freshly collected B6 and BDF1 epididymides from a sender colony to a recipient colony using a common package delivery service, during which the temperature was maintained at 5 degrees C or 7 degrees C for 2d. Sufficiently high fertilization rates (68.0-77.5%) were obtained for all experimental groups, except for B6 spermatozoa transported at 5 degrees C. These spermatozoa were successfully cryopreserved at the recipient facility and, yielded post-thaw fertilization rates of 27.6-66.4%. When embryos derived from the B6 spermatozoa that were transported at 7 degrees C were transferred into recipient females, 52.7% (38/72) developed to term. In conclusion, transportation of epididymides at refrigerated temperatures is a practical method for the exchange of mouse genetic resources between facilities, especially when these facilities do not specialize in sperm cryopreservation. For the B6 mouse strain, the transportation of epididymides at 7 degrees C rather than 5 degrees C, is recommended.

Multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis.

A case of multifocal micronodular pneumocyte hyperplasia (MMPH) associated with tuberous sclerosis is reported. MMPH is a rare pulmonary disorder characterized by the nodular proliferation of type II pneumocytes. In the case presented here, MMPH appeared as multiple, well-defined small nodules with ground-glass opacity. It is necessary to consider MMPH when small nodules with ground-glass opacity are observed on HRCT in patients with tuberous sclerosis.

Flow-injection EPR investigation on OH radical scavenging activity of Gd(III) containing MRI contrast media.

The OH radical scavenging activity of a series of Gd(III) MRI contrast media, such as Gd(III)DTPA, Gd(III)BMA and Gd(III)DO3A, were evaluated by means of EPR spin trapping measurements. The second order reaction rate constant (k2) occurring between Gd(III)DTPA and OH radical was estimated to be 3.26 x 10(10) (M(-1)s(-1)), which was ten times larger than that of the free ligand DTPA (3.86 x 10(9) M(-1)s(-1). The k2 values of Gd(III)BMA and Gd(III)DO3A were also determined to be 1.31 x 10(10) and 1.77 x 10(10) (M(-1)s(1)), respectively. The present results suggest that widely used Gd(III) containing MRI reagent exhibit OH radical scavenging activity, and these values of k2 are same order as that of ascorbic acid (1.16 x 10(10) M(-1)s(-1)) which has been well established to be the most powerful OH radical scavenger. Based on the EPR measurements performed for these Gd(III) complexes, a possible reaction mechanism of the OH radical scavenging action of these MRI contrast media will be discussed.

Comparative whole-body 201Tl and bone scintigraphies for the detection of bone marrow involvement in multiple myeloma.

The objectives of this study were to investigate the role of whole-body 201Tl-chloride scintigraphy in comparison with bone scintigraphy in the detection of bone marrow involvement in patients with multiple myeloma and to assess the follow-up evaluation using 201Tl-chloride. Twenty-one patients with untreated multiple myeloma were evaluated. 201Tl-chloride images were acquired 10 min (early) and 2 h (delayed) after the injection of 111 MBq 201Tl-chloride. Bone images were acquired 3 h after the intravenous injection of 740 MBq 99mTc-hydroxymethylene diphosphonate (HMDP). The 201Tl-chloride scan patterns were classified as normal, diffuse (presence of bone marrow), focal (localized areas of uptake) and diffuse+focal. The bone scan patterns were classified as normal and abnormal. Eight of the 21 patients also underwent 201Tl-chloride scintigraphy after chemotherapy for the evaluation of the therapeutic response. On the early 201Tl-chloride image, two patients showed a normal, 13 a diffuse, two a focal and four a diffuse + focal pattern. On the delayed 201Tl-chloride image, nine patients showed a normal, six a diffuse, four a focal and two a diffuse + focal pattern. Bone scintigraphy showed an abnormal accumulation in only five of the 21 patients. Of the eight patients who underwent follow-up 201Tl-chloride studies, the abnormal diffuse pattern was changed to a normal pattern on post-treatment scintigraphy in three, and the degree of abnormal 201Tl-chloride accumulation decreased in comparison with the pre-treatment scan in three. These six patients were considered to be in clinical remission. In the two remaining patients, the degree of abnormal 201Tl-chloride accumulation increased in comparison with the pre-treatment scan, and they were considered to be in clinical progression. 201Tl-chloride scintigraphy is a non-invasive tool, which may be more useful than bone scintigraphy for the diagnosis of multiple myeloma, and may be helpful in the follow-up of multiple myeloma.

99mTc galactosyl human serum albumin liver dynamic SPET for pre-operative assessment of hepatectomy in relation to percutaneous transhepatic portal embolization.

We have devised an original predictive residual index (PRI) using 99mTc diethylenetriaminepentaacetic acid galactosyl human serum albumin (99mTc-GSA) liver dynamic SPET for the pre-operative assessment of hepatectomy, including the prediction of residual liver function before hepatectomy. The aim of this study was to evaluate the usefulness of the PRI by using 99mTc-GSA liver dynamic SPET before and after percutaneous transhepatic portal embolization (PTPE) to induce compensatory hypertrophy of the remnant lobe, and to compare the results with the prognosis after hepatectomy. The subjects included eight patients with cholangiocellular carcinoma, five with gallbladder cancer, four with hepatocellular carcinoma and three with metastatic liver cancer. 99mTc-GSA liver dynamic SPET was performed immediately before and 2 weeks after PTPE. Dynamic SPET with 35 continuous rotations was performed to obtain the k-value according to the accumulation curve in each voxel (0.54 cm x 0.54 cm x 1.08 cm) of the liver immediately after a bolus injection of 185 MBq 99mTc-GSA. Each rotation consisted of 180 degrees turn in 64 steps in a 64 x 64 matrix. The acquisition time of each rotation was 35 s. We devised an original PRI by combining the k-value with functional liver volume which were measured by liver dynamic SPET. Hepatectomy was performed following the second SPET. The correlation between the PRI and post-operative patient prognosis was investigated retrospectively. The functional liver volume of the remnant lobe and the PRI significantly increased after PTPE compared with respective values before PTPE (P<0.005 and P<0.0001, respectively). Regarding the relationship between the PRI and the clinical course following surgery, post-operative complications were observed in only two patients. The PRI values of these two patients were 0.323 and 0.394. When the PRI was above 0.400, no patient had symptoms of hepatic failure. The results of this study suggest that, when the PRI value is above 0.400, there is a low probability of hepatic failure after hepatectomy. We conclude that the PRI devised in this study is useful in the pre-operative assessment of hepatectomy after PTPE.

99mTc-MIBI and 201Tl SPET in the detection of recurrent brain tumours after radiation therapy.

The purpose of this study was to evaluate whether Tc-hexakis-2-methoxyisobutylisonitrile ( Tc-MIBI) or Tl single photon emission tomography (SPET) could detect recurrent tumours in patients with previous radiation therapy for brain tumours. Dual SPET with Tc-MIBI and Tl was performed in 21 patients suspected of having recurrent brain tumours. SPET images were acquired 15 min (early) and 2 h (delayed) after injection. The ratio of the average counts for the region of interest in the lesion area and its mirror image in normal brain tissue was obtained. Early and delayed ratios were calculated. On the basis of histological and/or clinical findings, the final diagnosis was considered as recurrent tumours in 15 patients and radiation necrosis in six. Both ratios using Tc-MIBI and Tl were significantly higher in recurrent tumours than in radiation necrosis. Based on a cut-off of 5.89 of the early ratio using Tc-MIBI to distinguish between recurrent tumours and radiation necrosis, the accuracy was 90%. Based on a cut-off of 6.77 of the delayed ratio using Tc-MIBI, the accuracy was 86%. The corresponding values using cut-offs of 2.40 and 1.85 with Tl were 90% and 86%, respectively. However, within recurrent tumours, both ratios for Tc-MIBI were significantly higher than those for Tl. Early Tc-MIBI SPET may be especially useful for the detection of recurrent tumours in patients who have previously undergone radiation therapy for brain tumours.

Comparison of 201 Tl- with 67 Ga single photon emission tomography in the diagnosis of head and neck cancer recurrence.

The purpose of this study was to evaluate the usefulness of 201Tl single photon emission tomography (SPET) in comparison with 67Ga SPET for distinguishing recurrent tumours in patients previously treated for head and neck cancer. A total of 37 patients with suspicion of recurrent cancer were investigated. SPET images with 201Tl were acquired 10min (early) and 3h (delayed) and SPET images with 67Ga were acquired 72h, after injection. The visual and semiquantitative (T/N ratio) analysis were performed. On visual analysis, results from early 201Tl SPET were the same as those from delayed 201Tl SPET. The sensitivity, specificity and accuracy of the diagnosis of local recurrence using 201Tl SPET were all 100%. The three values using 201Tl SPET for neck lymph node metastases were 73%, 100% and 91%. The corresponding values using 67Ga SPET for local recurrence were 57%, 100% and 89%, respectively, and those using 67Ga SPET for neck lymph node metastases 55%, 100% and 84%, respectively. In the semiquantitative analysis, there was a statistically higher T/N ratio obtained using 201Tl when compared with 67Ga. 201Tl early SPET, especially, has the potential to replace 67Ga SPET in the follow-up of patients with head and neck cancer.

Delayed enhancement of hepatocellular carcinoma on dynamic CT: sign of extrahepatic collaterals after transcatheter arterial chemoembolization or transcatheter arterial chemoinfusion.

BACKGROUND: We examined the factors of delayed enhancement of hepatocellular carcinoma (HCC) on dynamic computed tomography (CT). METHODS: Dynamic CT and angiography were compared in 113 patients who had undergone transcatheter arterial chemoembolization or transcatheter arterial chemoinfusion and were suspected of developing new HCCs. RESULTS: Eight of 113 patients had HCC nodules that enhanced gradually from the arterial phase to the portal venous phase on dynamic CT and were fed by extrahepatic arteries on angiography. The feeding artery was an omental branch of the splenic artery in one lesion, an omental branch of the gastroduodenal artery in five, and the intercostal artery in two. CONCLUSION: We believe that the recurrence of HCCs delayed enhancement on dynamic CT because the hepatic artery was hidden and long narrow extrahepatic collaterals fed the tumor.

Phage display cloning and characterization of monoclonal antibody genes and recombinant Fab fragment against the CD98 oncoprotein.

The Fab gene of anti-CD98 heavy chain (h.c.) monoclonal antibody (mAb) HBJ127 was cloned and expressed as a recombinant Fab (rFab) fragment by means of a phage display system. The variable heavy and light chain genes of HBJ127 were found to be derived from VOx-1 and IgVk8-30 germline, respectively. Extensive somatic mutation was found in the heavy chain complementarity determining region 2. rFab fragment was purified homogeneously from crude bacterial lysates by Ni-chelate chromatography in a yield of 71.4 mg from 100 ml of culture. rFab fragment was reactive with the cell surface of CD98-positive cells irrespective of tissues of origin, but not with CD98-negative cells. The recognition site of the rFab fragment was identical to that of mAb since the binding of rFab fragment to HeLaS(3) cells was completely inhibited by pretreatment with an excess of mAb. The relative affinity values of rFab fragment and mAb were found to be 0.11 x 10(8) and 0.35 x 10(8) M(-1), respectively. Three-fold lower affinity of rFab fragment may be due to the difference of valency of the antibody preparation. Cell growth inhibition in vitro by rFab fragment preincubated with anti-Fab suggests that the rFab fragment produced by cloned gene-bearing Escherichia coli was identical to the Fab part of HBJ127 mAb. These results show that a small fragment with antigen binding activity similar to that of the parent mAb can easily be prepared by using a phage display system. To our knowledge, this is a first report of the production of anti-CD98 h.c. rFab fragment.

Non-specific eosinophilic granulomatous prostatitis responded favorably to an antimicrobial agent and a hydrocortisone.

A case of non-specific eosinophilic granulomatous prostatitis is presented. The patient was a 55-year-old man who was hospitalized with complaints of acute urinary retention and high-grade fever. Results of digital examination and transrectal ultrasonography of the prostate and elevated prostatic specific antigen were suggestive of prostatic cancer. Transrectal needle biopsy of the prostate was performed. Histological examination of the specimens revealed the formation of histiocytic granulomas with eosinophilic infiltration. The patient responded favorably to combination therapy with an antimicrobial agent and a hydrocortisone.

99mTc-MIBI SPECT in small cell lung cancer patients before chemotherapy and after unresponsive chemotherapy.

We evaluated the accumulation of 99mTc-MIBI in small cell lung cancer patients before chemotherapy and after unresponsive chemotherapy. The pre-chemotherapeutic group included 22 newly diagnosed patients. These patients underwent a 99mTc-MIBI SPECT study before starting chemotherapy. After chemotherapy, based on changes in tumor size, three different patterns of response (complete remission: CR, partial remission: PR and no change: NC) were defined. The post-chemotherapeutic group included 11 patients after chemotherapy who did not respond to chemotherapy. These patients underwent a 99mTc-MIBI SPECT study after completion of chemotherapy. SPECT images were acquired 15 min (early) and 2 hr (delayed) after injection of 99mTc-MIBI. With a region of interest technique, the early ratio, delayed ratio and retention index were calculated. Early and delayed ratios in pre-chemotherapeutic patients were significantly higher than those in post-chemotherapeutic patients. There were no significant differences between the pre-chemotherapeutic and post-chemotherapeutic patients in the retention index. In the pre-chemotherapeutic patients, early and delayed ratios for the CR and PR groups were significantly higher than those for the NC group. There were no significant differences in the retention index with respect to the tumor response. 99mTc-MIBI might be useful for evaluating the tumor chemosensitivity in patients with small cell lung cancer.

[Comparison of 133Xe gas dynamic SPECT and thin-section CT in patients with pulmonary emphysema].

PURPOSE: We assessed 133Xe gas dynamic single photon emission computed tomography (SPECT) by comparing washout axial images with thin-section CT (TSCT) in patients with pulmonary emphysema. METHODS: Twenty-three patients were studied. All patients were diagnosed as having pulmonary emphysema on the basis of TSCT. We compared TSCT of upper, middle and lower lung fields with 133Xe gas dynamic SPECT axial images at the corresponding levels during the 3 to 4 minutes of washout phase. If the degree of 133Xe gas retention or TSCT finding of ventral and dorsal parts was not the same, the images were divided into two parts. RESULTS: A total of 174 lesions in 23 cases were examined, but 3 lesions having no retention of 133Xe gas at equilibrium phase were excluded. The results showed that: there were 37 lesions (21.6%) with equivalent severity on both images; there were 42 lesions (24.5%) with more severity on 133Xe gas dynamic SPECT than on TSCT; and there were 92 lesions (53.8%) with more severity on TSCT than on 133Xe gas dynamic SPECT. The severity on 133Xe gas dynamic SPECT and TSCT was not always compatible. One of the reasons for the variable 133Xe gas retention even when the lesion had the same severity on TSCT, may be bronchial stricture which cannot be seen on TSCT. CONCLUSION: By comparison of axial images of 133Xe gas dynamic SPECT with CT images, we could recognize the areas of 133Xe gas retention in detail. Results suggest that 133Xe gas dynamic SPECT can be useful to identify ventilation impairment in pulmonary emphysema.

CT assessment of subtypes of pulmonary emphysema in smokers.

OBJECTIVE: To determine the incidence of subtypes of pulmonary emphysema (PE) identified by CT imaging in male patients who have a significant smoking history. PATIENTS AND SETTING: We reviewed 945 subjects (619 men and 326 women) who had undergone CT scanning. However, only the data for male subjects were analyzed due to there being too few female subjects. The male subjects were divided into the following two age groups: group A (age, 50 years). There were two subtypes of PE found: centrilobular emphysema (CLE) and paraseptal emphysema (PSE). Based on these subtypes, PE was divided into the following three categories: I (CLE or CLE-predominant); II (CLE and PSE of equal extent); and III (PSE or PSE-predominant). RESULTS: PE was found in 270 of 516 male smokers (10 of 38 female smokers had PE). Among male subjects, in age group A there were 53 subjects with some degree of PE (category I, 12 subjects [22.6%]; category II, 7 subjects [13.2%]; and category III, 34 subjects [64.2%]). Among men in age group B, there were 217 subjects with some degree of PE (category I, 109 subjects [50.2%]; category II, 23 subjects [10.6%]; and category III, 85 subjects [39.2%]). CONCLUSION: In age group A, men < 50 years of age who were in category III (PSE or PSE-predominant PE) predominated (34 of 53 subjects; 64.2%). In age group B, men > 50 years of age who were in category I (CLE or CLE-predominant PE) predominated (109 of 217 subjects; 50.2%).

[A case of ectopic pulmonary calcification appearing as diffuse ground-glass attenuation on HRCT].

A 50-year-old man was admitted to undergo an operation for aortic stenosis and insufficiency. Chest high-resolution CT (HRCT) showed diffuse areas with ground-glass attenuation in both lung fields. The shadows were not seen in the periseptal zones. A transbronchial lung biopsy specimen revealed ectopic interstitial calcification. Differential diagnosis upon observation of diffuse areas with ground-glass attenuation on HRCT included hypersensitivity pneumonitis and bronchopneumonia. In the peripheral region of the secondary pulmonary lobules, the microchemical environment of the alveoli tended to become alkalosed in comparison with the central area, the characteristic distribution of the areas of ground-glass attenuation may be explained by the differentiation of the acid-base balance between the peripheral and central regions of the secondary pulmonary lobules.

Tl-201 chloride and Tc-99m MIBI accumulation in lung adenocarcinoma in patients with and without distant metastases.

PURPOSE: The relation between Tl-201 chloride accumulation by the tumor and its distant metastatic potential were evaluated in patients with lung adenocarcinoma and compared with the same parameters achieved using Tc-99m MIBI. METHODS: Fifty-six patients with primary lung adenocarcinoma were examined before therapy was begun. They were classified according to the radiologic findings and pathologic diagnosis into two groups: distant metastases and no distant metastases. All patients underwent dual-isotope imaging with Tl-201 chloride and Tc-99m MIBI. Regions of interest were placed over the tumor uptake (T) and contralateral normal lung tissue (N) areas on one transverse view with clearly defined lesions, and the T:N ratio and retention index were calculated. RESULTS: The early and delayed T:N ratios and retention index using Tl-201 chloride SPECT in the distant-metastases group were significantly greater (P < 0.001 to P < 0.05) than were those in the no-distant-metastases group. There was no significant correlation between the T:N ratio and retention index and distant metastatic potential using Tc-99m MIBI SPECT. CONCLUSION: Tl-201 chloride SPECT may be more effective than Tc-99m MIBI SPECT for evaluating the distant metastatic potential of primary lung adenocarcinoma.

Comparison of 99Tcm-MIBI with 201Tl chloride SPET in patients with malignant brain tumours.

The purpose of this study was to evaluate the usefulness of 99Tcm-MIBI accumulation for the differentiation of histological diagnosis of malignant brain tumours in comparison with the findings obtained using 201Tl chloride. A total of 25 patients with malignant brain tumours were investigated. The histological categories of tumours included glioblastoma multiforme (n = 5), anaplastic astrocytoma (n = 4), malignant lymphoma (n = 5), and metastatic tumour (n = 11). Simultaneous dual single photon emission tomography (SPET) images with 99Tcm-MIBI and 201Tl were acquired 15 min (early) and 2 h (delayed) after injection, and the early ratio, delayed ratio and retention index were measured. The new indices 201Tl/99Tcm-MIBI ratios and 201Tl/99Tcm-MIBI retention index were also calculated. With respect to the histological type, a higher retention index using 99Tcm-MIBI was noted in glioblastoma multiforme compared with metastatic tumour. Higher values of both ratios using 201Tl were noted in glioblastoma multiforme compared to metastatic tumour. The value of the delayed ratio obtained using 201Tl was higher in glioblastoma multiforme than in anaplastic astrocytoma, and the value was also higher in malignant lymphoma than in metastatic tumour. The 201Tl/99Tcm-MIBI early ratio of glioblastoma multiforme was significantly higher than that of metastatic brain tumour. The 201Tl/99Tcm-MIBI retention index of malignant lymphoma was significantly higher than that of glioblastoma multiforme. In the histological type of tumour, 99Tcm-MIBI is not superior to 201Tl, but the combined indices using 201Tl/99Tcm-MIBI may add new information about differential diagnosis.