Neck lesions persistently seen in 131 iodine whole body scans: Are they thyroid remnants?

In not a few instances have nuclear medicine physicians encountered persistent neck lesions in 131I whole body scintigraphy despite giving repeated radioactive iodine therapy. Interpreting these lesions as still thyroid remnants served as a dilemma. This is a case of a 37-year-old female with papillary thyroid cancer. 131I whole body scans done before and one year after radioactive iodine therapy showed persistent and unchanged neck lesions. Further imaging with SPECT/CT showed laryngeal skeleton involvement. Rarity of vascular and lymphatic spread to the larynx has led to a small number of reported cases. Neck lesions should not always be immediately diagnosed as thyroid remnants.

Right-to-left shunting secondary to microvascular pulmonary arteriovenous malformation demonstrated by lung perfusion scintigraphy

Right-to-left shunting is usually associated with congenital conditions involving the heart, lungs, and the blood vessels that connect both organs. It is demonstrated by echocardiography, transesophageal ultrasound, CT scan, MRI and more definitively by conventional angiography. In this paper, we present a 16-year old female who manifested with progressive dyspnea, persistent cyanosis and decreased arterial oxygen saturation. Clinical assessment and arterial blood gas parameters suggested the presence of significant shunting. However, cardiac evaluation showed no intracardiac defects. High resolution CT scan of the chest with CT angiography of the pulmonary artery also showed no evidence of pulmonary vascular malformation or shunt anomaly. Lung perfusion scintigraphy performed after intravenous administration Tc99m-MAA showed tracer uptake in the brain, spleen and kidneys signifying the presence of a right-to-left shunt in the lungs. Cardiac catheterization later demonstrated the presence of primary pulmonary telangiectasia.

90Yttrium-ibritumomab tiuxetan radioimmunotherapy for refractory follicular lymphoma

This paper aims to discuss the sequential use of rituximab and 90Yttrium-ibritumomab tiuxetan, a novel treatment approach in the management of refractory follicular non-Hodgkin's lymphoma. Radioimmunotherapy (RIT), which combines the benefits of targeted radiation therapy and monoclonal antibody, has significantly increased the response rate well in excess of 50%. This is explained by the inherent radiosensitive nature of lymphoma cells. We present a case of a 56-year-old male with refractory follicular lymphoma. The patient was referred for RIT, the first case in the Philippines. The patient was pretreated with two doses of rituximab followed by an intravenous infusion of 90Y-ibritumomab tiuxetan (Zevalin). Hematologic nadir was reached six weeks following administration of the radioimmunotherapy. During this time, the patient developed melena. Hematologic recovery was noted after three weeks. Re-evaluation with computed tomography three months after treatment showed significant reduction in the tumor bulk and resolution of lymphadenopathies. This report underscores the importance and evolving role of radioimmunotherapy in the management of refractory non-Hodgkin's lymphoma.

Clinical utility of SPECT-CT co-registration imaging

The interpretation of nuclear medicine studies is largely based on function. However, this interpretation becomes more accurate and reliable when there is a corresponding precise anatomical localization. Hybrid systems are opening up a new era in SPECT imaging. A tertiary hospital in the Philippines has acquired the country's first hybrid imaging device combining a dual-detector, variable angle gamma camera with a low dose X-ray tube attached to the same gantry. This study evaluates the clinical utility of a hybrid imaging system, SPECT/CT for functional mapping with selected radiotracers. SPECT data were first interpreted alone and then re-assessed with the addition of SPECT/CT co-registered images. Patients referred for various nuclear medicine procedures with SPECT components in the first six months of operation studied for various clinical situations were evaluated in the study. Our study included sixty-four (64) patients in the first year of operation of SPECT/CT co-registered imaging systems. This included 23 with I-131, six with sulfur colloid, four with Gallium 67, five with Tc99m Sestamibi and 26 with Tc99m HOP. The pathologic sites in 28 out of 64 (44 percent) patients were noted in both SPECT and SPECT/CT co-registered images. Additionally, SPECT/CT co-registered images provided the precise anatomical localization in 12 (19 percent) patients not clearly evident in SPECT images alone and enabled the exclusion of disease in sites of physiologic tracer deposition in 16 (25 percent) patients found suspicious in SPECT alone leading to a change in the therapeutic approach. SPECT/CT allows a more precise interpretation of scintigraphic studies using selected radiotracers for various clinical situations. It provides additional information that improves diagnostic accuracy of SPECT and impacts on patient management indicating that SPECT/CT co-registered systems are suited for routine use in clinical practice.

Parathyroid scintigraphy and gamma probe-guided surgery in the management of parathyroid carcinoma

This paper aims to present one of the rarest types of malignancies, parathyroid carcinoma. Parathyroid carcinoma is an important cause of primary hyper par athyroidism. Diagnostic evaluation of patients presenting with signs and symptoms of hyperparathyroidism consists of serum calcium and parathyroid hormone determination, parathyroid imaging using ultrasound, computed tomography, magnetic resonance imaging, or Tc-99m sestamibi scintigraphy, and histopathologic evaluation of tissues after surgical intervention. Therapeutic management of an identified parathyroid tumor is by parathyroidectomy during neck exploration or radioisotope-guided with the use of a gamma probe. The histology of a resected tumor determines if the initial surgery completes the management, or, in cases of parathyroid carcinoma, if another completion surgical intervention is to be made. This paper will present a patient who has been initially diagnosed with primary hyperparathyroidism and was referred to our nuclear medicine department for parathyroid scintigraphy. The patient underwent MIRP and rapid intraoperative PTH determination. Histopathologic report on the tissues revealed parathyroid carcinoma. The patient underwent a second surgery for definitive treatment. This paper will discuss the clinical role of nuclear medicine in the diagnosis and surgical management of parathyroid carcinoma.