Ultrasonographic Findings of Medullary Thyroid Carcinoma: a Comparison with Papillary Thyroid Carcinoma

OBJECTIVE: This study was designed to evaluate the ultrasonographic (US) findings of medullary thyroid carcinoma (MTC) as compared to findings for papillary thyroid carcinoma (PTC). MATERIALS AND METHODS: The study included 21 cases of MTC that were surgically diagnosed between 2002 and 2007 and 114 cases of PTC that were diagnosed in 2007. Two radiologists reached a consensus in the evaluation of the US findings. The US findings were classified as recommended by the Thyroid Study Group of the Korean Society of Neuroradiology and Head and Neck Radiology (KSNHNR) and each nodule was identified as suspicious malignant, indeterminate or probably benign. The findings of medullary and papillary carcinomas were compared with use of the chi-squared test. RESULTS: The common US findings for MTCs were solid internal content (91%), an ovoid to round shape (57%), marked hypoechogenicity (52%) and calcifications (52%). Among the 21 cases of MTC nodules, 17 (81%) were classified as suspicious malignant nodules. The mean size (longest diameter) of MTC nodules was 19 +/- 13.9 mm and the mean size (longest diameter) of PTC nodules was 11 +/- 7.4 mm; this difference was statistically significant (p < 0.05). An ovoid to round shape was more prevalent for MTC lesions than for PTC lesions (p < 0.05). CONCLUSION: The US criteria for suspicious malignant nodules as recommended by the Thyroid Study Group of the KSNHNR correspond to most MTC cases. The US findings for MTC are not greatly different from PTC except for the prevalence of an ovoid to round shape.

Visualisation of medullary carcinoma thyroid with locally formulated 99mTC [V] DMS and comparison with 131I-MIBG scintigraphy

Technetium-99m [pentavalent] dimercaptosuccinic acid [99mTc [V] Dms] scintigraphy was performed in one patient with histopathologically confirmed medullary carcinoma thyroid [MCT] using a locally formulated kit. Marked uptake of the tracer by the primary and locally metastatic sites was noted. The same patient was also subjected to Iodine-131-metaiodobenzoilguanidine [131I-Mibg] scintigraphy and the results were found comparable. Better resolution, easy in-house formulation, labelling with 99mTc [V] Dms makes it a better imaging agent as compared to 131I-Mibg for the imaging of the primary and metastatic medullary carcinoma thyroid in our setup. Furthermore, the formulation of 99mTc [V] Dms is simple and convenient procedure. A 52 years old male patient of medullary carcinoma thyroid was diagnosed seventeen years back and successfuly operated for a solitary nodule in the neck at that time. On a routine follow-up visit he was found to have two discrete, firm, palpable nodules in front of his neck. To determine if the nodules were locally metastatic medullary carcinoma thyroid, the patient was prepared for imaging with 99mTc [V] DMS [locally formulated] and 131I-MIBG. The preparation included giving Lugol's iodine in sufficient quantity [10 drops of the solution three times a day for ten days dissolved in water or milk] to block the free pertechnetate uptake in case of 99mTc [V] DMS and 131 I uptake in 131I-MIBG scintigraphy by the thyroid gland. The patient was first subjected to 99mTc [V] DMS and later on to 131I-MIBG scintigraphy. A kit of renal dimercaptosuccinic acid [DMS] supplied by Nuclear Chemistry Division [NCD] Radioisotope Production Group [RIPG], Pakistan Institute of Nuclear Science and Technology [PINSTECH], Islamabad, Pakistan, was taken and 0.2 ml of sterile solution of 7.0% NahCO3 was added and adequately mixed. After that 15 mCi of 99mTc-pertechnetate fresh elute was added into it [upto 150 mCi can be added]. The radio-pharmaceutical [RP] was incubated for fifteen minutes. Quality Control [QC] tests were carried out and labelling efficiency was found to be > 90%. The RP was then injected into the median cubital vein of the forearm of the patient. For 99mTc [V] DMS imaging Toshiba scintillation camera with low-energy-all-purpose [LEAP] collimator was used. A 15% window centred at 140keV g rays energy was set for imaging. After two hours imaging was done for cervico-thoracic region and abdomen. After one week of the 99mTc [V] DMS the patient underwent 131I-MIBG scintigraphy. The 131I-MIBG was formulated at NCD, RIPG, PINSTECH Pakistan with labelling yield of > 90%, the 131I-MIBG was also injected into the median cubital vein by a slow i.v. infusion and having a close look at the vital signs like pulse, blood pressure and respiratory rates. Imaging was done on 1, 2 and 3 postinjection days. Siemens' scintillation gamma camera with large field of view coupled to high-energy-all-purpose [HEAP] parallel hole collimator was employed for imaging. The gamma camera was linked to on-line computer system MicroDelta and Micro Dot imager. The acquisition parameters were as follows: Symmetric energy window was set as 15% centred at the 364 keV Peak energy of 131I. All the images were interpreted by three experienced nuclear physicians in view of the clinical presentation of the patient. Marked uptake of 99mTc [V] DMS was seen in three foci of the neck, corresponding to the palpable nodules in the neck