Robbert B. T. Verkooijen

The success of 131I ablation in thyroid cancer patients is significantly reduced after a diagnostic activity of 40 MBq 131I

OBJECTIVE Dosimetry studies have shown that activities of 131I as small as 10-20 MBq may cause a stunning effect. A result of this stunning effect may be a lower success rate of the ablative 131I therapy for differentiated thyroid carcinoma (DTC). The aim of this study was to determine whether pre-therapeutic uptake measurement with 40 MBq 131I causes a lower success rate of ablation. DESIGN retrospective chart review study. PATIENTS, METHODS In two hospitals the ablation protocols differed in one respect only: in the one hospital no diagnostic 131I was applied before ablation (group 1, n = 48), whereas in the other hospital a 24-h uptake-measurement with 40 MBq 131I was performed (group 2, n = 51). Included were all DTC patients without distant metastases who had undergone 131I ablation between July 2002 and December 2005, and who had returned for 131I follow-up. Successful ablation was defined as absence of pathological 131I uptake on diagnostic whole-body scintigraphy and undetectable thyroglobulin-levels under TSH stimulation. RESULTS Overall, ablation was successful in 31/48 patients (65%) in group 1 and in 17/51 patients (33%) in group 2 (p=0.002). Multivariate analysis showed that pre-therapeutic uptake measurement using 40 MBq 131I was an independent determinant for success of ablation (p = 0.002). CONCLUSIONS After applying a diagnostic activity of 40 MBq 131I before ablation, the success rate of ablation is severely reduced. Consequently, the routine application of 131I for diagnostic scintigraphy or uptake measurement prior to 131I ablation is best avoided.

Radioiodine-131 in differentiated thyroid cancer: a retrospective analysis of an uptake-related ablation strategy.

In our hospital, a 24-h radioiodine-131 (131I) uptake-related ablation strategy is used in patients with differentiated thyroid cancer to destroy thyroid remnants after primary surgery. In this strategy, low doses of 131I are used, but data in the literature on its efficacy are conflicting. Therefore, we performed the present study to evaluate the clinical outcome of this ablation strategy. In this study, patients (n=235) were selected who underwent thyroidectomy for differentiated thyroid cancer, followed by an ablative dose of 131I. Approximately 6 months after ablation, treatment efficacy was evaluated using radioiodine scintigraphy and thyroglobulin (Tg) measurements. Successful ablation was defined as the absence of radioiodine uptake in the neck region (criterion 1). Tg values were determined 3–12 months after ablation (criterion 2). Based on criterion 1, unsuccessful ablation was found in 43.0% of cases. Pre-treatment uptake values were statistically significantly lower (P=0.003) in successfully ablated patients (mean 5.4%) than in unsuccessfully ablated patients (mean 8.2%). Based on criterion 2, unsuccessful ablation was found in 52.4% of patients. The uptake-related ablation strategy, using low doses of 131I, shows a relatively high treatment failure rate. Based on these results it is suggested that a lower ablation failure rate could be achieved by applying higher 131I doses in the ablation of thyroid remnants in differentiated thyroid carcinoma patients. In the case of lymph node metastases a further dose adjustment may be advisable.

The success rate of I-131 ablation in differentiated thyroid cancer: comparison of uptake-related and fixed-dose strategies

INTRODUCTION The aim of the study was to compare the success rate of an uptake-related ablation protocol in which the dose depends on an I-131 24-h neck uptake measurement and a fixed-dose ablation protocol in which the dose depends on tumour stage. METHODS All differentiated thyroid carcinoma patients with M0 disease who had undergone (near-) total thyroidectomy followed by I-131 ablation were included. In the uptake-related ablation protocol, 1100 (uptake >10%), 1850 (uptake 5-10%) and 2800 MBq (uptake <5%) were used. In the fixed-dosage ablation strategy, 3700 (T1-3, N0 stage) and 5550 MBq (N1 and/or T4 stage) were applied. We used I-131 uptake on whole-body scintigraphy and thyroglobulin-off values to evaluate the ablation 6-12 months after treatment. RESULTS In the uptake-related ablation protocol, 60 out of 139 (43%) patients were successfully treated versus 111 out of 199 for the fixed-dose ablation protocol (56%) (P=0.022). The differences were not statistically significant for patients with T4 (P=0.581) and/or N1 (P=0.08) disease or for patients with T4N1 tumour stage (P=0.937). CONCLUSION The fixed-dose I-131 ablation protocol is more effective in ablation of the thyroid remnant in differentiated thyroid carcinoma patients than an uptake-related ablation protocol. This difference is not observed in patients with a N1 and/or T4 tumour stage.

Indium-111 octreotide scintigraphy for the detection of non-functioning metastases from differentiated thyroid cancer: diagnostic and prognostic value.

In this prospective study, we evaluated the diagnostic and prognostic value of 111In-octreotide scintigraphy (SRS) in papillary and follicular thyroid carcinoma (DTC) with increasing thyroglobulin (Tg) levels but no response to treatment with 131I. Twenty-three consecutive patients (13 female, 10 male; mean age 55 years, range 13–81 years) with progressive DTC were selected for the study. All patients had non-functioning metastases, defined by no or slight uptake of 131I in metastases. Diagnosis of tumour progression was based on rising Tg levels during follow-up and was confirmed by radiological examination. Uptake on SRS was scored from 0 to 4. Data on initial tumour stage, histology, age, gender, Tg values, TSH levels, 131I treatment doses, intervals and survival were gathered. Seven patients died during follow-up. The overall sensitivity for the detection of metastases was 74%. The sensitivity was better in patients in whom 131I whole-body scintigraphy did not show any abnormal uptake (82%; 14/17) than in patients with faint 131I uptake (50%; 3/6). The 10-year survival rate was significantly different between patients with an uptake score of 0 or 1 (100%) and those with an uptake score of 2, 3 or 4 (33%) (P=0.001). Gender, log Tg and uptake on SRS significantly correlated with survival, but in stepwise analysis, 111In-octreotide uptake was selected as the most prognostic independent variable (hazard rate 6.25, P=0.006). We conclude that 111In-octreotide scintigraphy is a valuable clinical tool for the detection of non-functioning DTC metastases. The uptake seems to correlate with prognosis and survival.

Bone scintigraphy in mycobacterium avium osteomyelitis: a case report.

A 30-year-old woman who had a destructive Mycobacterium avium complex infection in the left inguinal fossa affecting the pubic bone underwent three-phase bone scanning to identify other possibly affected sites. Multiple skeletal lesions were seen scattered throughout the vertebral column, sternum, and pelvis. This case is presented to describe a rare extensive metastatic M. avium complex infection in an immunocompromised patient.