No abstract

Patients with DTC with pulmonary metastasis have a relatively favorable prognosis and response rate, as well as longer survival. The type of DTC is the only factor that affects the response to treatment.

Dextrocardia, although a rare cardiac abnormality, carries the same risk for cardiac events as other people. SPECT Myocardial perfusion imaging is a potentially helpful diagnostic tool in patients with dextrocardia. Due to swapping of lateral and septal walls on SPECT slices, although visual analysis is possible, quantitation is substantially limited. Here, we introduce a simple practical method to make quantitative analysis feasible and accurate. Case reportA 50-year-old male patient with known history of dextrocardia with situs inversus presented for cardiac evaluation. A dipyridamole gated SPECT myocardial perfusion imaging (G-SPECT MPI) was performed with same-day stress-rest protocol. As we knew that the patient had dextrocardia, we modified the acquisition protocol. The patient was positioned supine and imaging was acquired from left anterior oblique (LAO) to right posterior oblique (RPO) views. Other acquisition parameters were as routine (e.g., orientation: feet-in, number of projections: 32 and number of frames for gating: 8). First, Images were reconstructed and processed with routine protocol, then, with modified protocol (Figure 1). In modified protocol, we changed orientation of images from "Feet-in" to "Head-in". Analysis for gating was also performed with both protocols (Figure 2). DiscussionDextrocardia is a rare congenital abnormality of the heart with incidence of less than 0.01% [1]. The heart is positioned on the right side and the axis of left ventricle (LV) is directed toward the left side. In dextrocardia with situs inversus or mirror-image dextrocardia, the LV is positioned posterior and left to the right ventricle (RV). The position of other organs including visceral organs (e.g., liver, stomach and etc.) is also reversed [1].It has been shown that the risk of coronary artery disease in patients with dextrocardia is the same as that in general population [2,3]. SPECT MPI is a potentially helpful modality for cardiac assessment in these patients, although some modifications in acquisition protocol are required. Otherwise, perfusion abnormalities in LV myocardium will occur. The acquisition arc ranges from LAO to RPO. When images are reconstructed as routine, tomographic slices are visualized mirrored in a way that interventricular septum and lateral free wall are swapped and RV is located on the right side of image. Quantitative analysis usually reveals perfusion defect and motion abnormality in lateral segments of polar map, because septal wall of patients are compared to lateral wall in normal database. Therefore, quantitative analysis is not helpful in these situations and images are interpreted solely visually.

Optimal performance of diagnostic tests and correct interpretation depend on multiple factors, one of which is proper radiopharmaceutical preparation. Unwanted impurities result in altered distribution of radiopharmaceuticals and then poor-quality or uninterpretable studies. Therefore, following the reconstitution steps according to standard and validated protocols by the technologist is mandatory. Here, we present 2 cases with unexpected and less recognized distribution of Tc-methylene diphosphonate on bone scintigraphy.