The relationship between thallium uptake, blood flow, and blood pool activity in bone and soft tissue tumors

Evaluation of Undifferentiated Carcinoma of Nasopharyngeal Type with Thallium-201 and Technetium-99m MIBI SPECT

OBJECTIVE: To determine the value of 201-thallium (201-Tl) and technetium-99m sestamibi (Tc-99m MIBI) single photon emission computed tomography (SPECT) for detecting primary undifferentiated carcinoma of nasopharyngeal type (UCNT), residual/recurrent tissue, and lymph node involvement.

STUDY DESIGN AND SETTING: SPECT of head and neck was prospectively performed in 46 patients with a history of UCNT (201-Tl in 24 patients, Tc-99m MIBI in 22). CT/MRI findings, clinical follow-up, and pathohistological verification served as a gold standard for calculating sensitivity, specificity, and accuracy of each scintigraphic technique. Tumor-to-background index (T/Bg) was derived when SPECT findings were positive.

RESULTS: Sensitivity of 201-Tl SPECT was 87 percent, with 78 percent specificity, 83 percent accuracy, and T/Bg of 4.05 ± 1.50. Tc-99m MIBI SPECT had 85 percent sensitivity, 78 percent specificity, 82 percent accuracy, and T/Bg of 4.45 ± 1.27.

CONCLUSION AND SIGNIFICANCE: 201-Tl SPECT and Tc-99m MIBI SPECT are useful for detecting primary UCNT, residual/recurrent disease, and lymph node involvement. This use is particularly valuable after chemoradiotherapy when CT/MRI may be ambiguous.

Thallium-201 scintigraphy is an effective diagnostic modality to distinguish malignant from benign soft-tissue tumors

BACKGROUND

The aim of this study is to evaluate whether thallium-201 (201-Tl) scintigraphy can differentiate malignant from benign soft-tissue tumors.

METHODS

Between April 1995 and December 2005, 192 patients with soft-tissue tumors (85 malignant and 107 benign) underwent 201-Tl scintigraphy before treatment. Isotope uptake was used as a proxy for tumor-to-background ratio (TBR). The accuracy of TBR on early and delayed imaging was evaluated using the Mann-Whitney U and χ(2) tests.

RESULTS

There was a statistically significant difference in mean TBR on early and delayed imaging of malignant and benign soft-tissue tumors (124% ± 109% vs. 22% ± 42%, and 82% ± 83% vs. 12% ± 25%, P < 0.0001). A TBR cutoff of 20% indicated the probability of malignancy on early and delayed imaging (82% sensitivity and 77% specificity; 82% sensitivity and 84% specificity, P < 0.0001). Well-differentiated liposarcomas showed low isotope accumulation, while pigmented villonodular synovitis and giant cell tumors of the tendon sheath showed high isotope accumulation.

CONCLUSIONS

Thallium-201 scintigraphy can distinguish malignant from benign tumors with relatively high accuracy. With the exception of low grade liposarcomas and locally aggressive benign tumors, 201-Tl scintigraphy may be an effective diagnostic modality to differentiate malignant from benign soft-tissue tumors.

A comparative study of F-18 FDG PET and 201Tl scintigraphy for detection of primary malignant bone and soft-tissue tumors

PURPOSE

The purpose of this study was to compare 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and Tl-201 chloride (Tl) scintigraphy for detection of primary malignant bone and soft-tissue tumors.

MATERIALS AND METHODS

A total of 40 patients with suspicion of malignant bone and soft-tissue tumors were examined. FDG PET imaging was performed at 1-hour post-FDG injection. Tl planar and single photon emission computed tomography images were acquired 10 minutes (early) and 2 hours (delayed) after injection of Tl. We evaluated FDG and Tl uptake visually and semiquantitatively using standardized uptake value and tumor to contralateral normal tissue ratio on planar images, respectively.

RESULTS

Of the 33 patients with malignant tumors, all but 2 liposarcomas showed positive accumulation on FDG PET. However, all 7 benign lesions were also positive on FDG PET. Both early and delayed Tl images were positive for 27 of the 33 malignant tumors. Of the 6 false-negative cases on Tl images, 5 were liposarcomas. Both early and delayed Tl images were negative for 5 of the 7 benign lesions. The sensitivity of FDG PET for detection of primary malignant bone and soft-tissue tumors was 94% and the specificity, 0%. The corresponding values for Tl scintigraphy were 82% and 71%. The mean FDG standardized uptake value in malignant tumors was higher than that in benign lesions, but this difference was not statistically significant. Statistically significant differences were observed between malignant and benign lesions for both early and delayed tumor to contralateral normal tissue ratios.

CONCLUSIONS

FDG PET was found to be more sensitive than Tl scintigraphy for primary malignant bone and soft-tissue tumors, although it was less specific.

Prediction of final tumor response to preoperative chemotherapy by Tc-99m MIBI imaging at the middle of chemotherapy in malignant bone and soft tissue tumors: comparison with Tl-201 imaging

The aim of this study was to assess the predictive power of 99mTc-MIBI scintigraphy performed in the middle of chemotherapy, for the final tumor response to chemotherapy, and compare it to that of (201)Tl in malignant bone and soft tissue tumors (MBST). Sixty-eight patients with MBST underwent 99mTc-MIBI and 201Tl scintigraphies at 15 min after tracer injection before the first, and after the third, chemotherapy cycles. After five cycles of chemotherapy and tumor resection, therapeutic effect was assessed by histopathology. Less than 90% and > or =90% necrosis were judged as poor and good response to chemotherapy, respectively. Tracers uptake ratios were calculated by dividing the lesion count density by that of the background. 99mTc-MIBI perfusion index was also calculated. The % reduction of the perfusion index (DeltaPI) and uptake ratios (DeltaUR) calculated by 100 x [(prechemotherapy value--postchemotherapy value)/prechemotherapy value] were compared with histologic response. The sensitivity, specificity, and accuracy for the prediction of effective chemotherapy in 99mTc-MIBI imaging were 80%, 95%, 88% in DeltaUR, and 74%, 74%, 74% in DeltaPI, respectively. The area under the receiver operator characteristic curve (A(z)) of the 99mTc-MIBI-DeltaUR (0.923) was significantly higher than that of DeltaPI (0.809, p = 0.025) but only marginally higher than that of the 201Tl-DeltaUR (0.865, p = 0.079). A(z) in 201Tl (0.865) was not significantly different from that of DeltaPI (0.809, p = 0.35). 99mTc-MIBI imaging performed in the middle of chemotherapy well predicts the final tumor response to chemotherapy in patients with malignant bone and soft tissue tumors.

[Value of thallium 201-SPECT in typing brain space-occupying lesions]

OBJECTIVE

This study was designed to assess the diagnostic accuracy of single photon emission computed tomography with Tl-201 (SPECT Tl-201) to establish the tumoral or non-tumoral nature of brain space occupying lesions in comparison with usual diagnostic techniques.

MATERIAL AND METHODS

The study population consisted of 37 patients, 24 men (64.9 %) and 13 women (35.1 %), mean age 48 +/- 16 years. After establishing the clinical and radiological diagnosis of brain lesion, all patients underwent SPECT Tl-201, evaluating it only by subjective analysis and blinded to neuroestructural techniques. After surgical resection all patients were evaluated anatomopathologically to establish the histologic nature.

RESULTS

The sensitivity of SPECT Tl-201 (0.87) was higher than standard neuroimaging techniques (0.78). Specificity (0.43), positive (0.87) and negative (0.43) predictive values of SPECT were similar to neuroestructural procedures (MRI and CT scan) with 0.43, 0.82 and 0.38 values. Tumoral disease prevalence was 0.81. Neuroestructural procedures were non-conclusive in 18.9 % of the studies. No non-conclusive results were obtained with SPECT Tl-201.

CONCLUSIONS

SPECT Tl-201 is a diagnostic procedure of high sensitivity to establish the tumoral nature of brain lesions, with poor specificity, similar to structural X-ray techniques.

The predictive value of additional late blood pool imaging to the three-phase bone scan in the diagnosis of reflex sympathetic dystrophy in hemiplegic patients

Reflex sympathetic dystrophy (RSD) is a relative common sequel after hemiplegia. The diagnosis of RSD in hemiplegic patients presents difficult clinical problems, as the symptoms and signs of RSD are not specific and RSD may be due to reasons other than hemiplegia. Bone scintigraphy has been routinely used for the diagnosis of RSD; however, the optimal acquisition protocols, diagnostic patterns and the utility of quantitation are controversial. This prospective study was conducted to demonstrate the higher predictive value of an additional late blood pool image to the three-phase bone scan compared to the regular three-phase bone scans in RSD patients associated with hemiplegia. Thirty-four RSD patients were enrolled into the study. Bone scans according to the new protocol were obtained for all patients. Those patients with either negative or positive bone scans with no evidence of RSD were followed for 6 months. The patients had positive bone scan findings and were symptomatic at the time of the study. Of these, seven patients (58.3%) subsequently became symptomatic and five patients (41.7%) remained asymptomatic at 6 months. None of the patients with negative bone scans had symptoms of RSD on presentation except one case. We conclude that the addition of a late blood pool image increases the predictive value and has an impact on initiating early treatment in asymptomatic patients.

A comparative study of2O1T1 scintigraphy and three-phase bone scintigraphy following therapy in patients with bone and soft-tissue tumors

OBJECTIVE

The purpose of this study was to evaluate the usefulness of 201Tl scintigraphy in comparison with three-phase bone scintigraphy in the differentiation of residual/recurrent tumors from post-therapeutic changes, in patients previously treated for bone and soft-tissue tumors.

METHODS

Thirty-five 201Tl and three-phase bone scintigraphy scans were obtained for 30 patients with a history of bone or soft-tissue tumor who had undergone chemotherapy, radiation therapy, tumor resection, or a combination of these treatments. The planar 201Tl images were acquired 10 mins (early) and 2 hrs (delayed) after the intravenous injection of 111 MBq 201Tl-chloride. Three-phase bone scintigraphy was performed using 740 MBq 99mTc-HMDP at the same lesion site as for 201Tl imaging. The blood flow images were obtained every 10 sec for 2 mins and were immediately followed by the blood pool image after 5 mins. Three to 4 hrs later, bone images were obtained. 201Tl and three-phase bone scintigraphies were correlated with the histopathologic findings and/or clinical follow-up of more than 3 months.

RESULTS

Of the 35 cases, 15 were free of disease and 20 had residual or recurrent tumors. Of the 20 residual or recurrent cases, all had true-positive 201Tl early and delayed scans, while bone scintigraphy was true-positive on the blood flow, blood pool and bone images in 16, 18 and 12 cases, respectively. 201Tl early and delayed images and 99mTc-HMDP blood flow and blood pool images were false-positive in one patient. The histology of this false-positive case showed the presence of lymph proliferative tissue.

CONCLUSIONS

Although 201Tl uptake after treatment does not always indicate recurrence, 201Tl scintigraphy may still be more useful than three-phase bone scintigraphy in the follow-up of patients with bone and soft-tissue tumors following therapy.

Low-grade chondrosarcomas: a difficult target for radionuclide imaging. Case report and review of the literature

Bone scan with Tc-99m (technetium) diphosphonate is sensitive, but non-specific for musculoskeletal tumors. Tl-201 (thallium), Tc-99m-sestamibi, Tc-99m-tetrofosmin, and F-18-fluorodeoxyglucose (F-18-FDG) can visualize tumors more specifically and are therefore useful in orthopedic oncology. However, cartilaginous tumors are characterized by histological and biological features, which potentially impair specific radionuclide imaging. A case of a patient with a low-grade primary chondrosarcoma of the femur and a false negative Tl-201 scan is presented. Tc-99m-based tumor-localizing compounds (sestamibi, tetrofosmin), as well as metabolic and receptor-imaging radiopharmaceuticals have also been reported to fail in low-grade chondrosarcomas imaging. Low cellularity, mitochondrial specialization and the presence of an efflux membrane pump may contribute to poor imaging. A negative Tl-201 or Tc-99m-sestamibi scan should be interpreted with caution, when the possibility of a chondrosarcoma is not negligible.

Intense 201 Tl uptake in giant-cell tumour of bone

The aim of this study was to determine the characteristics and clinical usefulness of 201Tl scintigraphy in giant-cell tumour of bone (GCT). Twenty-one patients with histopathologically proven benign GCT (22 lesions; 18 primary and four recurrent) underwent 201Tl scintigraphy. We also studied conventional osteosarcoma (10 lesions), a very common primary malignant bone tumour; and chordoma in the sacrum (four lesions), an entity requiring differential diagnosis from GCT of the sacrum. Early and delayed planar imaging was performed at 15 min (early) and 3 h (delayed) after the intravenous injection of 201Tl chloride (111 MBq). The Tl uptake ratio was calculated by dividing the count density of the tumour region of interest (ROI) by that of the background ROI. All GCT lesions showed increased Tl uptake in both early and delayed images. The mean Tl uptake ratios of primary GCT were 4.7 (range, 2.0-11.1) in the early images and 2.2 (range, 1.4-3.6) in the delayed images, and those of recurrent lesions were 5.8 (range, 2.4-11.5) in the early images and 2.7 (range, 2.0-4.3) in the delayed images. There were no significant differences between the uptake ratios in GCT and osteosarcoma, but the values of GCT tended to be higher than those of osteosarcoma, 3.1 (range, 1.7-4.4) in the early images and 1.8 (range, 1.3-2.3) in the delayed images. Chordoma did not show appreciable Tl uptake: the uptake ratio was 1.19 (range, 0.98-1.5) in the early images and 1.1 (range, 1.0-1.3) in the delayed images. In GCT, a benign lesion, Tl scintigraphy demonstrated marked uptake in both primary and recurrent lesions with no exceptions, precluding the use of Tl scintigraphy for the differential diagnosis of GCT from malignant tumours. However, the Tl scintigraphy can be used for excluding GCT when no lesional Tl uptake is observed, and diagnosing recurrent lesions on post-operative follow-up.

Thymic lesions in patients with myasthenia gravis: characterization with thallium 201 scintigraphy

PURPOSE

To assess thallium 201 ((201)Tl) single photon emission computed tomography (SPECT) for evaluation of thymic lesions associated with myasthenia gravis (MG), including lymphoid follicular hyperplasia (LFH) and thymoma.

MATERIALS AND METHODS

(201)Tl SPECT and computed tomography (CT) were performed preoperatively in 46 patients with MG who had undergone thymectomy. SPECT was conducted 15 (early image) and 180 (delayed image) minutes after (201)Tl injection. Results were visually assessed, and (201)Tl uptake ratios (thymic lesion count density/lung count density) were measured for quantitative analysis. Uptake was analyzed among the normal thymus, LFH, and thymoma patient groups.

RESULTS

Histopathologic results indicated a normal thymus, LFH, and thymoma in 19, 16, and 11 patients, respectively. Mean uptake ratios in the normal thymus, LFH, and thymoma were 0.96 (95% CI: 0.90, 1.03), 1.14 (95% CI: 1.04, 1.25), and 1.87 (95% CI: 1.56, 2.25), respectively, on early images and 1.09 (95% CI: 1.00, 1.18), 1.65 (95% CI: 1.48, 1.85), and 2.03 (95% CI: 1.65, 2.50), respectively, on delayed images. Thymoma showed more intense (201)Tl accumulation than did the normal thymus (P <.001) and LFH (P <.001) on early images. Both thymoma (P <.001) and LFH (P <.001) displayed more intense uptake than did the normal thymus on delayed images.

CONCLUSION

(201)Tl SPECT can enable differentiation between normal thymus, LFH, and thymoma in patients with MG.

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.

Increased accumulation of Tl-201 in monostotic Paget's disease of the patella: evaluation with quantitative analysis

Monostotic Paget's disease of the patella was detected with Tc-99m MDP and Tl-201 scans. Diffuse intense uptake of MDP in the left patella was observed on the blood-pool and late phases of the bone scan. Tl-201 imaging was performed to differentiate a malignant process and showed diffuse marked accumulation at the same site. Semiquantitative analysis of the patella region on both Tc-99m MDP and Tl-201 scans did not support a diagnosis of cancer. Radiographs showed the features of Paget's disease of the bone. Findings of a pathologic evaluation were compatible with the diagnosis of osteitis deformans. This case represents the unusual skeletal involvement of monostotic Paget's disease of the bone in the patella. Tl-201 accumulation in the Paget's lesion was suggested to be caused by increased metabolic activity of the lesion but was not indicative of a malignant process.

Correlation of 99mTc-sestamibi uptake with blood-pool and osseous phase 99mTc-MDP uptake in malignant bone and soft-tissue tumours

Technetium-99m-sestamibi (99mTc-MIBI) imaging is a well-established modality in oncologic investigations. The current study aimed to investigate whether any relationship could be found between 99mTc-MIBI uptake and local perfusion in malignant bone and soft-tissue tumours. It also aimed to compare 99mTc-MIBI images with those of technetium-99m-methylene diphosphonate (99mTc-MDP) bone scintigraphy with regard to the activity distribution pattern, intensity and lesion extension. The study group included 24 patients with various bone and soft-tissue tumours. Three-phase bone scintigraphy and 99mTc-MIBI studies were performed within the same week before any surgical and therapeutic intervention. Images were evaluated visually and quantitatively using regions of interest (ROIs) over the lesion and adjacent normal tissue. The 99mTc-MIBI study was positive with varying degrees of uptake (range, 1.4-5.3). The mean 99mTc-MIBI uptake and 99mTc-MDP blood-pool and osseous phase activity ratios were 2.5 +/- 0.5, 2.8 +/- 1.0 and 5.5 +/- 4.0, respectively. The correlation between the 99mTc-MIBI uptake and blood-pool ratios was 0.70 (P<0.05). While activity distribution patterns were in agreement in 99mTc-MIBI and blood-pool images in the majority of cases, 99mTc-MIBI better delineated tumour viability and extension in five cases. In conclusion, 99mTc-MIBI accumulation shows a reasonable correlation with blood-pool uptake assuming the presence of multifactorial mechanisms in addition to local hyperaemia. Better delineation of tumour outlines and cellular activity seems to be an advantage of 99mTc-MIBI scintigraphy which may be helpful in the evaluation of musculoskeletal tumours.

Evaluation of histopathological differentiation in lung adenocarcinoma patients using 201Tl-chloride and 99Tcm-MIBI SPET

The purpose of this prospective study was to evaluate the relationship between thallium-201 chloride (201Tl) and technetium-99m hexakis 2-methoxyisobutylisonitrile (99Tcm-MIBI) accumulation and histopathological differentiation in primary lung adenocarcinoma. A total of 43 patients with primary lung adenocarcinoma were investigated. The patients were divided into well differentiated (n = 17), moderately differentiated (n = 14) and poorly differentiated (n = 12) carcinoma groups. Simultaneous dual single photon emission tomography (SPET) images with 201Tl and 99Tcm-MIBI were acquired 15 min (early) and 2 h (delayed) after injection. Using a region of interest technique, the tumour-to-normal lung ratio was calculated for both early (early ratio) and delayed (delayed ratio) images. The retention index was calculated using the formula delayed ratio/early ratio. Uptake of the radionuclides was compared with the classification of tumour differentiation grading. The mean (+/- SD) values of the early ratio, delayed ratio and retention index using 201Tl were 2.19+/-0.72, 2.28+/-0.71 and 1.06+/-0.16, respectively, in the well differentiated group, 2.38+/-0.83, 2.48+/-0.84 and 1.08+/-0.23, respectively, in the moderately differentiated group, and 2.87+/-0.75, 3.60+/-1.51 and 1.22+/-0.21, respectively, in the poorly differentiated group. Both the ratios and the retention index using 201Tl were significantly lower in the well differentiated group than in the poorly differentiated group. The delayed ratio using 201Tl in the moderately differentiated group was also significantly lower than that in the poorly differentiated group. There were no significant differences in either ratio or the retention index among the three groups using 99Tcm-MIBI. 201Tl SPET is superior to 99Tcm-MIBI SPET for the grading of histopathological differentiation of primary lung adenocarcinoma.

Thallium-201 SPECT with triple-headed gamma camera for differential diagnosis of small pulmonary nodular lesion 20 mm in diameter or smaller

AIM

Although thallium-201 (201Tl) has been used for the diagnosis of lung cancer, its detectability of small pulmonary nodules is not known. The aim of this study was to evaluate the ability of 201Tl SPECT for the differential diagnosis for the pulmonary nodules 20 mm in diameter or smaller.

METHODS

201Tl SPECT was performed in 31 patients suspected of having primary lung cancer. The final diagnosis was established by histology, and tumor size was 10 to 20 mm in diameter. Twenty of 31 patients had malignant tumors, including squamous cell lung cancer (n = 5), adenocarcinoma (n = 14) and small cell lung cancer (n = 1), but in none of them was there mediastinal lymphnode involvement.

RESULTS

Ten of 20 malignant tumors and 1 of 11 benign lesions demonstrated significant 201Tl uptake, so that the positive predictive value, negative predictive value, sensitivity and specificity for the diagnosis of lung cancer were 90.9% (10/11), 50.0% (10/20), 50.0% (10/20) and 90.9% (10/11), respectively.

CONCLUSION

These data suggest that sensitivity for detecting lung cancer 20 mm or less in diameter may be insufficient, but even in patients with small pulmonary nodules, a positive 201Tl result is highly predictive of lung cancer.

Diagnostic value of TI-201 and three-phase bone scintigraphy for bone and soft-tissue tumors

PURPOSE

Although TI-201 is highly sensitive for detecting bone and soft-tissue tumors, its uptake is not specific for malignant lesions. This study assessed the differentiation of malignant and benign lesions and evaluated the sensitivity, specificity, and accuracy of TI-201 imaging and three-phase bone scans.

MATERIALS AND METHODS

Forty bone and soft-tissue tumors (16 malignant and 24 benign) were evaluated. TI-201 static images were acquired 10 minutes (early) and 2 hours (delayed) after injection of the radionuclide. Within 14 days, three-phase bone scintigraphy was performed using Tc-99m HMDP with the patient in the same position. The count ratio of the lesion compared with the normal contralateral or adjacent site (L:N ratio) was measured.

RESULTS

With TI-201 scintigraphy, mean (+/- SD) values of early and delayed L:N ratios were 3.36 +/- 1.25 and 2.88 +/- 1.20, respectively, in malignant lesions; and 1.88 +/- 1.14 and 1.48 +/- 0.76, respectively, in benign lesions. TI-201 accumulation in benign lesions was significantly less than that of malignancies on early and delayed images. However, an overlap of both ratios between malignant and benign lesions was seen. No such significance was detected on three-phase bone scintigraphy (L:N ratios of malignant and benign tumors were 2.57 +/- 1.22 and 2.24 +/- 2.11, respectively, for blood flow imaging; 2.41 +/- 0.78 and 2.26 +/- 1.54, respectively, for blood pool imaging; and 2.80 +/- 2.10 and 2.89 +/- 4.55, respectively, for bone imaging). When we assumed that the tumor was malignant when the delayed TI-201 L:N ratio exceeded the blood pool phase L:N ratio with bone scintigraphy, the sensitivity rate was 81%, specificity rate was 100%, and accuracy rate was 93%.

CONCLUSIONS

TI-201 imaging for bone and soft-tissue tumors was better than three-phase bone scintigraphy alone but was not good enough to clearly differentiate malignant lesions from benign ones. TI-201 scintigraphy, performed in combination with three-phase bone scintigraphy, may be superior to either one of the two imaging procedures alone for bone and soft-tissue tumor diagnosis.

A new semiquantitative method for comparing brain tumor uptake of Tc-99m sestamibi and TI-201

PURPOSE

We describe a new method for measuring brain tumor uptake of TI-201 and Tc-99m sestamibi (MIBI) that permits the semiquantitative comparison of tracer uptake to yield comparable "tumor bulk" ratios. We tested this method in patients treated recently and remotely with chemotherapy to determine if this method could identify differences between these two patient groups.

METHODS

Eleven patients with high-grade astrocytoma underwent TI-201 and Tc-99m MIBI SPECT. Each patient received 5 mCi TI-201 intravenously followed by SPECT using a dual-head gamma camera. This was immediately followed by an intravenous injection of 20 mCi Tc-99m MIBI and repeated SPECT. Four patients had recent therapy (from 1 day to 6 weeks before SPECT) and seven had remote treatment (>1 year before SPECT). Regions of interest were outlined in the tumor area using a computer-automated program to include all counts above background activity. Tumor activity counts were obtained from this region of interest. The tumor region of interest was mirrored to the contralateral uninvolved cerebral hemisphere to obtain background control count activity. A hypothetical volume of the number of pixels with background count activity necessary to constitute the tumor count activity (tumor bulk) was calculated using the ratio of total tumor counts (Ct), subtracting background (Cb), and dividing by the average counts per pixel in the control region (Cab). This was multiplied by the number of pixels (P), the pixel volume (Vp), and summed over all sections (i) involved with tumor. This method yields the equation tumor bulk =

RESULTS

The mean Tc-99m MIBI to TI-201 tumor bulk ratio was 1.03 (range, 0.81 to 1.12) in four patients who had recently received chemotherapy. The mean Tc-99m MIBI to TI-201 tumor bulk ratio was 1.55 (range, 1.46 to 1.64) in seven patients who had remote therapy. The difference in the Tc-99m MIBI to TI-201 tumor bulk ratio between the two groups was significant (P = 0.0001). Patients who received recent chemotherapy had relatively lower Tc-99m MIBI uptake compared with TI-201. In remotely treated patients, uptake of the Tc-99m MIBI was greater compared with TI-201.

CONCLUSION

This method allows semiquantitative comparison of different tracer uptake values independent of tracer dose and reduces the variability in drawing a region of interest when measuring tumor uptake. Among the patients studied, those who had recent chemotherapy showed a low Tc-99m MIBI to TI-201 ratio. This method of measuring "tumor bulk" can provide a useful index of viable tumor size in evaluating early tumor response and during ongoing chemotherapy.

Thallium and FDG uptake by atelectasis with bronchogenic carcinoma

We report a case of bronchogenic carcinoma with atelectasis studied by T1-SPECT and FDG-PET. In the carcinoma, abnormally high uptake of T1 and FDG were detected, but in the region of atelectasis, an abnormally high uptake of T1 with a relatively low uptake of FDG were observed. On quantitative analyses, the T1 retention indexes of the tumor and atelectasis were 29.7 and 42.0. The mean SUVs of FDG of the tumor and the atelectasis were 8.92 and 1.28. T1-SPECT could not distinguish the atelectasis from the carcinoma. FDG-PET was superior to T1-SPECT in this case in detecting malignancy and distinguishing it from atelectasis.

Predicting chemotherapeutic response to small-cell lung cancer of platinum compounds by thallium-201 single-photon emission computerized tomography

Thallium-201 single-photon emission computerized tomography (SPECT) was used to clarify the relationship between 201Tl uptake and the response in chemotherapy to platinum compounds in 21 patients with small-cell lung cancer. 201Tl-SPECT scans were obtained twice: at 15 min (early scan) and 120 min (delayed scan) after an intravenous injection of 111 MBq (3 mCi) of thallium-201 chloride. We obtained the uptake ratio from each scan and calculated the retention index:uptake ratio = region of interest uptake/contralateral normal lung uptake; retention index = (delayed ratio - early ratio)/early ratio. After 201Tl scintigraphy, 12 patients received chemotherapy consisting of platinum compounds and nine were treated with chemoradiation. Among patients receiving only chemotherapy, the retention index correlated with the responses to chemotherapy. In an in vitro study, ouabain, an inhibitor of the Na,K-ATPase pump, reduced sensitivity to cisplatin and inhibited intracellular thallium uptake in the small-cell lung cancer cell line. These studies suggest that 201Tl-SPECT is a useful indicator of response to chemotherapy with platinum compounds in small-cell lung cancer, and that Na,K-ATPase is commonly involved in transporting both thallium and platinum compounds into cancer cells.

Thallium-201 SPECT in differentiating bone infarction from metastatic lesions in osteosarcoma

The authors present a case of bone infarction in the proximal epiphysis of the right tibia, which was caused by preoperative intraarterial chemotherapy for osteosarcoma. MR imaging revealed that suspected metastases had inhomogeneous signal intensity similar to that of the primary tumor, which made a metastatic lesion difficult to exclude. On TI-201 SPECT, no accumulation was found in the lesions, confirming that they were not osseous metastases. Consequently, this enabled limb salvage surgery to be performed with joint preservation. Intraoperative biopsy revealed no viable tumor cells in the lesion, and bone infarction was suspected. TI-201 SPECT was very useful, not only in differentiating bone infarction from tumor progression, including metastatic lesions, but also in the determination of the operative technique.

The role of nuclear medicine in primary bone and soft tissue tumors

Although there is a limited role initially for staging the disease of primary bone and soft tissue tumors and for differentiation of benign from malignant lesions, nuclear medicine studies are recommended before starting treatment. A total body bone scan that includes a three phase study for the involved region helps to outline the vascularity of the lesion and both soft tissue and bony involvement, as well as involvement of other bones. A thallium 201 chloride or technitium 99m methoxy isobutyl isonitrile (SestaMIBI) tumor imaging study is recommended for baseline study and for future reference to evaluate the response to preoperative chemotherapy. This is of special importance to determine whether the patient needs an amputation or a limb-salvaging procedure. A follow-up thallium or 99mTc sesta MIBI study is not recommended early after surgery. A waiting period of at least 2 months is essential to avoid false-positive uptake caused by postoperative changes although this could be differentiated by comparing the ratios of lesion uptake in both early and delayed thallium imaging and with the ratios from the blood pool phase of the bone scan. Persistent thallium uptake in delayed images accompanied by ratios that are higher than the blood pool ratios is highly indicative of early recurrence. In the future, F-18 FDG tumor imaging acquired either on dedicated positron-emission tomography (PET) systems or by using a dual head gamma camera for coincidence detection will replace thallium and 99mTc sesta MIBI in those centers that have access to this technology. This is especially important at sites where thallium and MIBI have limitations because of normal uptake in adjacent organs.

Short-period-induced hypertension could improve tumor-to-nontumor ratios of radiolabeled monoclonal antibody

This study was undertaken to find optimum period of hypertensive treatment for the improvement of tumor targeting of 111In-labeled monoclonal antibody. Angiotensin II was infused into tumor-bearing mice at an infusion rate of 2.0 micrograms/kg/min determined by the dose-finding study. The infusion was continued for up to 72 h, and biodistribution of 111In-DTPA-A7, a murine IgG1, was observed 72 h postinjection. Tumor-to-nontumor ratios were best improved with the infusion for 0.5-3 h. However, with the longer infusion, the effect deteriorated by the increase of nontumor uptakes, and body-weight loss became remarkable. It could be concluded that hypertensive treatment for a short period could be safely performed to benefit targeting of radiolabeled monoclonal antibody.

Osteosarcoma

Over the last several decades, significant advances have been made in our ability to understand and treat osteosarcoma. In this article we describe the diagnosis, evaluation, and treatment of patients with this disease. The surgical issues are discussed. We review the major clinical trials that have led to our current level of understanding. The current studies for the treatment of osteosarcoma are described.

Tl-201 scintigraphy, mammography and ultrasonography in the evaluation of palpable and nonpalpable breast lesions: a correlative study

PURPOSE

To determine the feasibility of Tl-201 as a tumor localizing agent in palpable and nonpalpable breast lesions, in comparison with mammography and ultrasonography (US), and to evaluate the contribution of these modalities to each other in obviating biopsy.

MATERIALS AND METHODS

Seventy-two palpable and nonpalpable breast lesions were prospectively classified as benign, indeterminate, or malignant according to the sonographic and mammographic criteria and were further analyzed with Tl-201 scanning. These classifications were compared with biopsy results. The sensitivity, specificity, accuracy, false positive and false negative rates (FPR, FNR), negative and positive predictive values (npv, ppv) were calculated for each individual modality and combination of modalities to evaluate the contribution of these three techniques to each other.

RESULTS

Of 72 lesions 52 were histologically malignant and 20 were benign. Overall, mammography was the most sensitive (92%) and Tl-201 was the most specific (75%) of the three modalities. Mammography + Tl combination was the most specific (90%) and accurate (97%) of dual combinations. In mammographically or sonographically indeterminate cases, Tl-201 was much more specific (75% versus 37% for mammography and US) and more accurate (82% versus 36% for mammography and 54% for US) than the other two modalities, and mammography + Tl combination was significantly superior to other dual combinations (87% specific and 91% accurate). Use of Tl-201 scanning as an adjunct to mammography + US combination increased the specificity, ppv, and accuracy rates overall, particularly in mammographically or sonographically indeterminate cases.

CONCLUSIONS

In mammographically and sonographically indeterminate breast lesions thallium scanning may be offered as a third step of investigation to obviate biopsy.

Tl-201 uptake and retention in a Warthin's tumor

We report scan findings of Tl-201 in a case of histologically proved Warthin's tumor. Dual isotopes acquisition was performed in a case of left parotid Warthin's tumor. Both early and delayed Tc-99m-pertechnetate (Tc-99m) images showed increased uptake at the tumor. Tl-201 scan also showed an increase of uptake on the early image and retention on the delayed image. The uptake ratios of Tl-201 were 3.0 (early) and 2.3 (delayed). Scan findings of Tl-201 in a case of Warthin's tumor were similar to those of Tc-99m, and the interpretation of Tl-201 images should be accompanied with Tc-99m images.

Intense and prolonged Tl-201 accumulation in a slow growing bronchioloalveolar carcinoma

Thallium-201 SPECT was performed to evaluate a pulmonary lesion in a 73-year-old male which had been considered to be an inflammatory lesion for two years. The lesion has slowly increased in size on x-CT. Tl-201 was intensely taken up and retained in the lesion, suggesting a malignant lesion. Histological examination revealed that the lesion was bronchioloalveolar carcinoma. This case suggested that Tl-201 uptake of pulmonary carcinoma would not be necessarily related to cell growth rate.

Early and delayed thallium-201 scintigraphy in thyroid nodules: the relationship between early thallium-201 uptake and perfusion

Seventy-six patients with thyroid nodules were studied. Initially, 74 MBq of thallium-201 was injected. The thyroid gland was imaged 15 min (early) and 3 h (delayed) after the injection. Thereafter, 185 MBq technetium-99m pertechnetate was injected. Immediately after the injection, a 1-min perfusion image was acquired, followed by an image at 20 min. Increased early and delayed 201Tl uptake compared with the contralateral thyroid tissue was adopted as the criterion for malignancy. Sensitivity, specificity and negative predictive values were found to be 85%, 64% and 78%, respectively, in operated patients, but these values were 86%, 87% and 95%, respectively, in the whole group, including patients followed with fine-needle aspiration biopsy. With the purpose of investigating the relationship between perfusion and early 201Tl uptake, both perfusion and early images were graded comparing nodular activity with contralateral thyroid activity. There was a poor correlation between perfusion and 201Tl uptake. The correlation was even worse in hyperactive nodules. It is concluded that early and delayed 201Tl imaging should not be used in the differential diagnosis of cold nodules and that early 201Tl uptake seems to be more closely related to factors other than perfusion.

Effect of induced hypertension with angiotensin II infusion on biodistribution of 111in-labeled monoclonal antibody

We investigated whether induced hypertension could enhance tumor uptake of monoclonal antibody. 111In-DTPA-A7 (IgG1 against 40kD tumor associated glycoprotein) was injected into colon carcinoma xenografted mice which were subcutaneously implanted with micro-osmotic pump containing angiotensin II (AT-II). Biodistribution was observed in groups of mice infused with AT-II at rate of 0.5 micrograms/kg/min (L) or 1 microgram/kg/min (H) and compared with a group of mice infused with saline (S). Tumor uptake of 111In-A7 in L and H was 1.32 and 1.57 times greater than S at 48 h after intravenous injection of A7. Normal organ uptakes also tended to be increased by AT-II infusion. Further study is needed to get optimum effect of hypertensive treatment on biodistribution of radiolabeled MoAb.

Quantitative evaluation of thallium-201 uptake in predicting chemotherapeutic response of osteosarcoma

Thallium-201 has been shown to be useful in predicting tumour viability in patients undergoing neoadjuvant chemotherapy for osteogenic sarcoma. Early studies relied upon qualitative assessment of analog images to obtain predictive results. Recently, the lesion to normal tissue uptake ratio of 201Tl has been used in evaluating bone and soft tissue sarcomas. This study attempts to quantitate changes in tumour to normal tissue ratio following chemotherapy. Eight consecutive patients with classical osteosarcoma received standard preoperative chemotherapy with a combination of cisplatin, adriamycin and high-dose methotrexate. 201Tl gamma scintigraphic images were obtained both before and after chemotherapy. The average counts taken over the tumour divided by that from the contralateral normal tissue area yielded a tumour-to-normal tissue (T/N) ratio. The percentage change in the T/N ratio before and after preoperative chemotherapy was correlated with the percentage of tumour necrosis from pathological section. The median post-chemotherapy T/N ratio was 1.85 (range 0.5-7.7). The median percentage change in T/N ratio after chemotherapy was -58% (range +26% to -83%). The median percentage of necrosis from pathological section was 80% (range 0%-95%). There was a good correlation between the percentage of tumour necrosis and the percentage change in T/N ratio (rank correlation coefficient r = 0.84, P = 0.0085). Quantitative assessment of changes in 201Tl uptake by osteosarcoma correlates well with tumour necrosis after preoperative chemotherapy. This method may be used to predict response to chemotherapy at an earlier stage, enabling the clinician to consider alternative chemotherapeutic regimens or salvage surgery.

Sensitivity and specificity of thallium-201 single-photon emission tomography in the functional detection and differential diagnosis of brain tumours

The aim of this retrospective study was to assess the contribution of thallium-201 single-photon emission tomography (SPET) in the detection and differential diagnosis of brain tumours. In 90 patients 201Tl SPET was performed because of clinical or radiological suspicion of tumoral invasion, completed by technetium-99m hexamethylpropylene amine oxime and 99mTc-sestamibi SPET in some patients. For all tumours, diagnosis was based on biopsy or autopsy. Other diagnoses were made only after clinical and radiological follow-up for at least 6 months. Histologically tumours consisted of astrocytoma stage I or II (number of patients, n = 6), astrocytoma stage III (n = 8), glioblastoma multiforme (n = 14) and oligodendroglioma (n = 3), brain metastasis (n = 14), lymphoma (n = 3), meningioma (n = 3), pituitary adenoma (n = 2), pineal tumour (n = 1), colloid cyst (n = 1) and craniopharyngioma (n = 1). False-negative studies included pineal tumour (n = 1), colloid cyst (n = 1), craniopharyngioma (n = 1), astrocytomas stage I or II (n = 6) and stage III (n = 3), oligodendroglioma (n = 2) and metastasis in the brain stem (n = 1). Additional metastases approximately < 1.5 cm were not detected in two patients and 201Tl SPET underestimated tumoral extent in one patient suffering from glioblastoma multiforme (n = 1). A false-positive study was obtained in a patient with skull metastasis (n = 1). All 15 patients who were finally shown to suffer from ischaemic infarction had a normal SPET study 9-28 days after the onset of symptomatology. Of five patients with haemorrhagic infarction, studied within 2 weeks, four were false-positive. Of six patients with intracranial haemorrhage, studied 9-39 days later, one showed focal 201Tl accumulation. Two further false-positive studies consisted of angioma and epidural haematoma. Finally, SPET studies were normal in six patients with definite diagnosis of (reactive) gliosis (n = 3), Binswanger's encephalopathy (n = 1), postinfectious encephalopathy (n = 1) and multiple sclerosis (n = 1). In the patient population presented, sensitivity of 201Tl SPET for supratentorial brain tumours was 71.7% and specificity was 80.9%. Clinical information and control SPET studies in combination with early, 30-min and 3- to 4-h delayed imaging may be expected to improve on these figures. On the other hand it seems that, in addition to tumoral histology, the presence of tumours in the fossa posterior and small volumes contribute to the occurrence of false-negative 201Tl SPET studies.

Thallium-201 for oncological imaging in children

Many pediatric centers are beginning to accumulate a large experience in the use of thallium-201 (201Tl) imaging with 201Tl requires a state-of-the-art high-resolution gamma camera computer system with single photon emission computed tomography (SPECT) capability and a physician-directed tailored examination. Tumor imaging with 201Tl, with its multifactorial localization mechanisms that are different from those for gallium-67, offers a distinct advantage over gallium tumor imaging with a short total imaging time. Tumors are variable in avidity and intensity of thallium uptake. Primary and metastatic disease can be detected with 201Tl scintigraphy. Baseline pretreatment determination of thallium avidity is crucial to its efficacy in therapeutic response assessment. Adjunctive SPECT imaging provides greater sensitivity for lesion detection and direct comparison of physiology (thallium uptake) with anatomy (computed tomography and magnetic resonance imaging). The sensitivity and specificity for detection of pediatric brain tumors has been reported as 77% and 93%, respectively. Thallium-201 brain SPECT also provides a less expensive and more readily available alternative to positron emission tomography for assessing the functional state of pediatric brain tumors. Extremity osteogenic sarcoma and Ewing's sarcoma have 100% sensitivity for 201Tl uptake pretreatment. Early results confirm an association between 201Tl uptake and histological tumor response. The determination of residual/recurrent disease versus thymic rebound and other nonneoplastic change in thallium-avid lymphoma, rhabdomyosarcoma, and germ cell tumors that involve the thorax can be confirmed with a 201Tl SPECT examination. Soft-tissue tumors elsewhere in the body may be detected with 201Tl scintigraphy. Thallium-201 does not exhibit 100% specificity for tumors. False-positive 201Tl uptake has been seen in histiocytosis X, benign bone tumors, stress fractures, and inflammation.