Vol 10, No 2 (2007)
Clinical nuclear medicine
Published online: 2007-05-23
The value of simultaneous co-registration of 99mTc- MDP and 131Iodine in metastatic differentiated thyroid carcinoma
Nucl. Med. Rev 2007;10(2):98-105.
Abstract
BACKGROUND: The lack of anatomical details in standard 131Iodine
whole body scanning (131I WBS) interferes with the proper
localization of metastatic differentiated thyroid carcinoma (DTC)
lesions. In addition, nearby or overlapping variable physiological
distribution of 131I may affect the specificity of 131I uptake,
giving indeterminate results. The aim of this study was to demonstrate
the clinical usefulness of simultaneous co-registration
of 99mTc MDP bone scanning as an anatomical landmark with
131I scanning in the evaluation of metastatic DTC.
MATERIAL AND METHODS: Twenty-five patients (16 females and 9 males, mean age ± SD = 52 ± 13 years) with metastatic DTC (17 papillary, 8 follicular), were included. Whole body scanning using a 256 x 1024 matrix and an 8 cm/min scan rate were obtained 48 hours after oral administration of 185-370 MBq 131I and 2 hours after IV administration of 185-370 MBq 99mTc MDP using a dual head gamma camera equipped with high energy parallel hole collimators. Occasionally, additional simultaneous co-registration of localised detailed images was also performed using a 256 x 256 matrix size. The two planar images were fused with optional fusion of SPECT images.
The data from standard 131I scanning and fused 131I/ 99mTc-MDP scanning were separately assessed by two nuclear medicine physicians. Fusion images were considered to improve image interpretation in comparison with standard 131I scanning when they provided better localization of lesions.
RESULTS: All lesions in the present study were validated by radiological images and clinical follow up for at least 12 months. Forty-eight metastatic lesions were confirmed as follows: 2 in the skull, 10 in the neck, 20 in the thorax, 12 in the pelvic-abdominal region and 4 in the extremities. Standard 131I WBS showed 54 extra-thyroidal foci with 8 false positive lesions of which 2 were located in the scalp and 6 in the pelvic-abdominal region extra-skeleton (i.e. sensitivity 100%, specificity 86%). Out of the 48 validated lesions, 16 were indeterminately localized: 10 in the thorax (3 mediastinal nodal lesions, 5 vertebral lesions and 2 ribs) and 6 in the pelvic-abdominal region (2 upper sacral, 2 sacroiliac region and 2 ischial bone). Fusion images confirmed the precise localization of the pathological uptake in the validated 48 lesions (sensitivity 100%, specificity 100%). There were 2 (4%) indeterminate lesions in fused planar imaging that were clearly localized via fused SPECT images.
CONCLUSIONS: Fusion images using simultaneous co-registration of 131I and 99mTc MDP scanning is a simple and feasible technique that improves the anatomically limited interpretation of scintigraphy using 131I alone in patients with metastatic differentiated thyroid carcinoma. The diagnostic advantage of this technique seems to be more apparent in the thoracic and pelvic- abdominal regions in contrast to the neck and extremities.
MATERIAL AND METHODS: Twenty-five patients (16 females and 9 males, mean age ± SD = 52 ± 13 years) with metastatic DTC (17 papillary, 8 follicular), were included. Whole body scanning using a 256 x 1024 matrix and an 8 cm/min scan rate were obtained 48 hours after oral administration of 185-370 MBq 131I and 2 hours after IV administration of 185-370 MBq 99mTc MDP using a dual head gamma camera equipped with high energy parallel hole collimators. Occasionally, additional simultaneous co-registration of localised detailed images was also performed using a 256 x 256 matrix size. The two planar images were fused with optional fusion of SPECT images.
The data from standard 131I scanning and fused 131I/ 99mTc-MDP scanning were separately assessed by two nuclear medicine physicians. Fusion images were considered to improve image interpretation in comparison with standard 131I scanning when they provided better localization of lesions.
RESULTS: All lesions in the present study were validated by radiological images and clinical follow up for at least 12 months. Forty-eight metastatic lesions were confirmed as follows: 2 in the skull, 10 in the neck, 20 in the thorax, 12 in the pelvic-abdominal region and 4 in the extremities. Standard 131I WBS showed 54 extra-thyroidal foci with 8 false positive lesions of which 2 were located in the scalp and 6 in the pelvic-abdominal region extra-skeleton (i.e. sensitivity 100%, specificity 86%). Out of the 48 validated lesions, 16 were indeterminately localized: 10 in the thorax (3 mediastinal nodal lesions, 5 vertebral lesions and 2 ribs) and 6 in the pelvic-abdominal region (2 upper sacral, 2 sacroiliac region and 2 ischial bone). Fusion images confirmed the precise localization of the pathological uptake in the validated 48 lesions (sensitivity 100%, specificity 100%). There were 2 (4%) indeterminate lesions in fused planar imaging that were clearly localized via fused SPECT images.
CONCLUSIONS: Fusion images using simultaneous co-registration of 131I and 99mTc MDP scanning is a simple and feasible technique that improves the anatomically limited interpretation of scintigraphy using 131I alone in patients with metastatic differentiated thyroid carcinoma. The diagnostic advantage of this technique seems to be more apparent in the thoracic and pelvic- abdominal regions in contrast to the neck and extremities.
Keywords: simultaneous Co-registrationdifferentiated thyroid carcinomaIodine-131 scantechnetium-99m-MDP bone scan
