Role of thallium-201 in the diagnosis of solitary bone lesions

To study the efficacy of thallium-201 as tumor seeking agent and to study its role in therapeutic response

BACKGROUND

Tumour seeking characteristics of TL-201 have been underutilized. The study was undertaken to evaluate the role of TL-201 scintigraphy in tumour imaging.

METHODS

A total of 50 cases were studied over a period of 18 months (13 lymphomas, 11 breast carcinoma, 10 lung cancer, 6 of soft tissue sarcoma, 2 bone tumours and 4 cases each of thyroid and brain tumours). Thallium-201 chloride was injected IV in the dose range of 3-5 mCi. Imaging was done using Siemen's ECAM dual headed gamma camera. Mean tumour to background ratio (T/B ratio) was calculated for all the positive cases. Descriptive statistical analysis was carried out.

RESULTS

Findings revealed a sensitivity of 94.12%, specificity 87.5%, PPV 94.12%, NPV 87.50% and accuracy of 92% for TL-201 tumour imaging. The mean T/B ratio for the true positive cases at 10 min and at 3 h was 1.81 and 1.99 respectively, the difference being 0.18 (P value <0.001). Amongst them, the mean T/B ratios for low-grade tumours were 1.45 ± 0.32 at 10 min and 1.63 ± 0.38 after 3 h with difference of 0.176 (P < 0.001). For the high-grade tumours the ratios were 2.08 ± 0.35 and 2.26 ± 0.41 respectively with a difference of 0.186 (P < 0.001).

CONCLUSION

Thallium-201 scintigraphy is a useful tumour imaging modality in cases of thyroid, breast, brain, lung, soft tissue and bone tumours and lymphomas. A T/B ratio of 1.63 ± 0.38 in 3 h-delayed imaging is suggestive of low-grade tumours. For high-grade tumours a ratio of 2.26 ± 0.41 should be considered significant.

Structure and Activities of Nuclear Medicine in Kuwait

The practice of nuclear medicine in Kuwait began in 1965 as a clinic for treating thyroid diseases. The practice developed gradually and until 1981 when the Faculty of Medicine established the Division of Nuclear Medicine in the Department of Radiology, which later became a separate department responsible for establishing and managing the practice in all hospitals of Kuwait. In 1987, a nuclear medicine residency program was begun and it is administered by Kuwait Institute for Medical Specializations originally as a 4-year but currently as a 5-year program. Currently there are 11 departments in the ministry of health hospitals staffed by 49 qualified attending physicians, mostly the diplomats of the Kuwait Institute for Medical Specializations nuclear medicine residency program, 4 academic physicians, 2 radiopharmacists, 2 physicists, and 130 technologists. These departments are equipped with 33 dual-head gamma cameras, 10 SPET/CT, 5 PET/CT, 2 cyclotrons, 1 breast-specific gamma imaging, 1 positron-emitting mammography, 10 thyroid uptake units, 8 technegas machines, 7 PET infusion systems, and 8 treadmills. Activities of nuclear medicine in Kuwait include education and training, clinical service, and research. Education includes nuclear medicine technology program in the Faculty of Allied Health Sciences, the 5-year residency program, medical school teaching distributed among different modules of the integrated curriculum with 14 didactic lecture, and other teaching sessions in nuclear medicine MSc program, which run concurrently with the first part of the residency program. The team of Nuclear Medicine in Kuwait has been active in research and has published more than 300 paper, 11 review articles, 12 book chapters, and 17 books in addition to 36 grants and 2 patents. A PhD program approved by Kuwait University Council would begin in 2016.

Diagnostic value of Thallium-201 scintigraphy in differentiating malignant bone tumors from benign bone lesions

OBJECTIVE

This retrospective study aims to evaluate the diagnostic capacity of thallium-201 (201Tl) scintigraphy for differentiating malignant bone tumors from benign bone lesions.

METHODS

Between January 2006 and December 2012, 279 patients with bone lesions (51 malignant and 228 benign) underwent 201Tl scintigraphy before treatment. To evaluate 201Tl uptake, we investigated tumor-to-background contrast (TBC) as well as TBC washout rate (WR). The differences of TBC on early and delayed images and WR were estimated by the Mann-Whitney U test. Receiver operating characteristic (ROC) analyses were used to determine the cut-off TBC values for differentiating malignant bone tumors from benign bone lesions.

RESULTS

There were statistically significant differences in median TBC between malignant tumors and benign lesions. These differences occurred for early imaging (1.57 vs. 0.09, p < 0.001) as well as for delayed imaging (0.83 vs. 0.07, p < 0.001). However, there was no statistical difference in WR between malignant tumors and benign lesions (44 vs. 43 %, NS). The chosen TBC cut-off value was 0.68 for early imaging and 0.38 for delayed imaging. Using these cut-off values, the prediction of malignancy had a 77 % sensitivity, 74 % specificity, and 75 % accuracy for early imaging and an 80 % sensitivity, 76 % specificity, and 77 % accuracy for delayed imaging.

CONCLUSIONS

201Tl scintigraphy may have the ability to distinguish malignant bone tumors from benign bone lesions.

Stress fracture at the junction of the middle and distal third of the ulnar diaphysis in a spinner bowler: a case report and a review of the literature

Stress fractures of the ulnar shaft are uncommon injuries, which have been documented in a variety of sports. The location of the fracture is influenced by the activity and mechanism of injury with which it is associated. The combined traditional approach of clinical history, physical examination, plain radiographs and nuclear scintigraphy for unusual stress fracture may be troublesome. This report is the first to describe a stress fracture at the junction of the middle and distal third of the ulnar diaphysis in a bowler due to chronic torsional stress. We discuss the possible mechanism of injury and describe the diagnostic imaging. A review of the literature is also given and compared with the findings and data of this case.

Sensitivity and specificity of thallium-201 scintigraphy for the diagnosis of malignant vertebral fractures

OBJECTIVE

To evaluate the accuracy of thallium-201 (201TI) scintigraphy in distinguishing a benign from a malignant recent non-traumatic vertebral fracture.

METHODS

STUDY DESIGN--Single center, prospective study. PARTICIPANTS--Patients hospitalized for a recent non-traumatic vertebral fracture. EVALUATION--Usual clinical, laboratory and radiological assessment; 201TI vertebral scintigraphy: patients were injected with iv 3 mCi 201TI. Early and delayed images of the fractured vertebra were obtained. DATA ANALYSIS--(1) Two examinators, unaware of the other findings, rated the images as hyperfixation or not of the fractured vertebra; (2) the ratio (average count per pixel of the fractured vertebra/normal adjacent vertebrae) were calculated. The FINAL DIAGNOSIS was established on the result of vertebral biopsy or on follow-up.

RESULTS

Twenty-one patients were included. The final diagnosis was a benign vertebral fracture in 14 patients and a malignant vertebral fracture in 7. The sensitivity, specificity, positive and negative predictive values for a malignant fracture on early 201TI vertebral scintigraphy images were 28.6, 92.9, 66.6, and 72.2%, respectively, and on delayed images were 28.6, 100, 100, and 73.7%, respectively. The ratio of lesioned over normal tissue was not increased in malignant, compared with benign fractures.

CONCLUSION

The weak sensitivity does not support the wide use of 201TI bone scintigraphy to distinguish a benign from a malignant recent non traumatic vertebral fracture. However, the high specificity suggests that such evaluation might be proposed prior to vertebral biopsy in some difficult cases.

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.

Bone and Tl-201 scintigraphy in a case of hereditary multiple exostoses

A 17-year-old girl with hereditary multiple exostoses, who was thought to have malignant transformation of an exostotic lesion, was examined by bone and Tl-201 chloride scintigraphy. Scintigraphy showed markedly intense uptake by the lesion, whereas Tl-201 imaging did not. Bone scintigraphy revealed intense to moderate uptake in other exostotic lesions, but none was apparent on the Tl-201 study. The lesion was resected and the histopathologic diagnosis was osteochondroma. Negative findings of Tl-201 scintigraphy may not exclude the possibility of chondrosarcoma, and the utility of this method may be limited. However, Tl-201 scintigraphy appears to have a useful role in differentiating malignant transformation from benign osteochondroma in hereditary multiple exostoses.

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.

The role of radionuclides in primary musculoskeletal tumors beyond the 'bone scan'

Radionuclides represent a means of functional imaging, which is able to reflect the metabolic state of tissues. Recently developed radiotracers and older radiotracers with newer applications, imaged through single photon emission computed tomography (SPECT) and positron emission tomography (PET), can provide significant information in the diagnosis, grading, therapy response or recurrence of primary musculoskeletal tumors. The unique ability of these radiotracers to demonstrate non-invasively the efflux pump rate, which is a common reason of therapy failure, as well as the metabolic and proliferative rates of the tumors should be a powerful tool in the orthopaedic oncology in the evaluation of musculoskeletal tumors.

Two cases of pediatric bone disease (eosinophilic granuloma and Brodie's abscess) showing similar scintigraphic and radiographic findings

Two 9-year-old patients with femoral bone lesions were referred to the authors' institution within a few days of each other. Both showed similar radiographic, magnetic resonance imaging, and scintigraphic findings. The radiographs showed osteolytic lesions in the right femoral diaphyses, and gadolinium-DTPA-enhanced magnetic resonance imaging revealed inhomogeneous enhancement. Tc-99m HMDP showed marked linear accumulation with relatively low central uptake in the right femoral shafts, and TI-201 scintigraphy showed considerable uptake corresponding to the area seen with Tc-99m HMDP. Histologic analysis confirmed eosinophilic granuloma in the first patient and Brodie's abscess in the second. The radiographic and scintigraphic findings in Brodie's abscess may be similar to those in eosinophilic granuloma.

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.

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.

Diagnostic bone scanning in oncology

Over the last several decades bone scanning has been used extensively in the evaluation of oncology patients to detect bone involvement. It can provide information about disease location, prognosis, and the effect of therapy. Bone scanning offers the advantages of whole body evaluation and the detection of lesions earlier than other techniques. However, as newer diagnostic tools become available, indications for bone scanning must be revised and the results combined with these other tests in order to provide optimum patient care. Advances in instrumentation and the subsequent improvement in image quality have allowed nuclear medicine physicians to provide more accurate bone scan interpretations. By optimizing image acquisition, it is often possible to determine lesion characteristics, which are more likely to represent malignancy. Knowledge of disease pathophysiology and other specific properties of the patient's primary tumor, along with subsequent correlation of scan abnormalities to patient history, physical examination, previous studies, and other radiological examinations, is essential for determining lesion significance. The differential diagnosis of a scan abnormality should also include consideration of both false normal and abnormal causes. The final interpretation should be clearly communicated to the clinician with appropriate recommendations for further evaluation. Only through careful attention to the patient, the clinician, and appropriate study acquisition parameters will bone scanning maintain its place in the evaluation of oncology patients.

Identification of AIDS-related tuberculosis with concordant gallium-67 and three-hour delayed thallium-201 scintigraphy

Concordant gallium-67 and thallium-201 uptake has been described in malignant lesions. More recently, 201Tl accumulation has been described in some benign conditions. The authors report three HIV-positive patients who underwent 67Ga and 201Tl scintigraphy. These studies revealed concordant 67Ga and 201Tl uptake and tumour was erroneously diagnosed. All three patients were finally diagnosed as having tuberculosis.

Diagnosis of malignant change in Paget's disease by Tl-201

Scintigraphy using Tc-99m MDP and Tl-201 was performed in a patient with polyostotic Paget's disease and sarcomatous degeneration in the right iliac bone. Tc-99m MDP imaging showed abnormal uptake in both types of lesions. Tl-201 imaging showed increased uptake in the sarcomatous lesion and absent uptake in pagetic lesions. This result supports the idea that Tl-201 scintigraphy may have a potential role to play in the differentiation of Paget's disease from malignancy. To the authors' knowledge, Tl-201 has never been reported for the detection of sarcomatous change of pagetic bone.

Comparison of Tc-99m MIBI and Tl-201 uptake in musculoskeletal lesions

The aim of this study was to make a comparison between the uptake of Tc-99m MIBI and Tl-201 in evaluation of musculoskeletal lesions. Fourteen cases were studied. Each study consisted of a Tl-201 study followed by a Tc-99m MIBI scan. In addition, a whole-body bone scan was performed in each patient to visualize bone metastases. Tl-201 and Tc-99m MIBI uptakes were evaluated by visual assessment and by using lesion-to-background (L/B) ratio. The authors found increased Tl-201 uptake with a mean L/B ratio of 2.81 and less Tc-99m MIBI uptake with a mean L/B ratio of 2.18 in malignant lesions. Both agents showed lower uptake with mean L/B ratios of 1.6 and 1.2 in benign lesions, but there was no statistical difference between the uptakes of either Tl-201 or Tc-99m MIBI in those with malignant and those with benign lesions. In addition, false-positive imaging was observed with both Tl-201 and Tc-99m MIBI. The results demonstrated that Tl-201 and Tc-99m MIBI accumulations in musculoskeletal lesions are not specific for malignancy.

Correlation of the findings of thallium-201 chloride scans with those of other imaging modalities and histology following therapy in patients with bone and soft tissue sarcomas

We performed a retrospective [corrected] study to evaluate the imaging potential of thallium-201 as compared with other imaging modalities in differentiating residual/recurrent tumors from post-therapy changes in patients with musculoskeletal sarcomas. 201Tl scans, magnetic resonance imaging (17), X-ray computed tomography (6) or contrast angiography (6) studies in 29 patients previously treated for musculoskeletal sarcomas were correlated with either histopathologic findings (26 patients) or 2-year clinical follow-up (three patients). All imaging studies were acquired within 2 weeks. Ratios of 201Tl tumor uptake to the contralateral (28 patients) or adjacent region of interest were calculated. When qualitative interpretation was in doubt, only those cases with a ratio of 1.5 or more were considered suggestive of recurrent of residual viable tumor tissue. Residual or recurrent tumor tissue was verified in 21 patients by biopsy. All had true-positive 201Tl scans while the other imaging modalities were true-positive in 20 and equivocal in one. In eight patients, there was no evidence of viable tumor tissue as proven by biopsy in five and long-term clinical follow-up in three. 201Tl scan was false-positive (ratio 1.5) in one patient and true-negative in seven while the other imaging modalities had four false-positives. The average 201Tl ratios were 2.8+/-1.1 in the true-positive cases and 1.3+/-0.3 in the true-negative cases. The percentage sensitivities, specificities, and accuracy for 201Tl were 100%, 87.5%, and 96.5% versus 95%, 50%, and 82.7% respectively for other imaging modalities. These results indicate that 201Tl scintigraphy is more accurate than other imaging modalities in differentiating residual/recurrent musculoskeletal sarcomas from post-therapy changes.