Quantitation in Dextrocardia on myocardial perfusion imaging: how to perform quantitative analysis using Cedars-Sinai software

Abstract

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.

Assessment of Myocardial Viability Using Nuclear Medicine Imaging in Dextrocardia

“…Ayeni et al acquired MPS images of situs inversus totalis using feet-in supine positioning and 2 processing methods; the second method applied feet-first prone positioning, which was entered in the processing software and allowed the lateral wall and septum to be reconstructed in the normal axis (3). Qutbi et al suggested a change from feet-in during acquisition to head-in or prone during processing to correct the orientation of the lateral wall and septum (5,6).…”

“…Many case reports have provided guidance about positioning and image processing using MPS in dextrocardia patients (3)(4)(5)(6)(7)(8)(9); however, there are fewer reports on assessing myocardial viability using 18 F-FDG PET.…”

Sidik Perfusi Miokard SPECT/CT Pada Pasien Dekstrokardia Dengan Dugaan Penyakit Arteri Koroner

“…Apabila pada pasien ini dilakukan modifikasi protokol dengan kepala mengarah ke dalam (head in) maka gambaran perfusi yang dihasilkan sama interpretasinya dengan populasi dengan letak jantung normal, namun memerlukan suatu perangkat lunak (software) yang khusus untuk pasien dekstrokardia. [16][17][18] Pemeriksaan SPM menunjukan adan ya defek perfusi parsial reversibel pada se bagian apeks, segmen apiko septal, segmen apiko-mid anterior, dan apiko-basal infero-lat eral. Summed stress score adalah 11, summed rest score 2, dan summed difference score 9.…”

“…Apabi la pemeriksaan dilakukan dengan modifika si protokol, yaitu posisi kepala mengarah ke dalam alat (head in) maka citra perfusi dan interpretasi yang dihasilkan akan sama den gan populasi umum (Gambar 6), namun me merlukan suatu perangkat lunak (software) yang khusus untuk pasien dekstrokardia. [16][17][18] Beberapa kamera gamma dapat mempunyai perangkat lunak yang berguna untuk akuisi si dan interpretasi dekstrokardia. Protokol ini harus dilakukan dengan baik dan benar agar tidak terjadi kesalahan interpretasi dalam me nentukan dinding lateral dan dinding septal ventrikel kiri.…”

“…Protokol ini harus dilakukan dengan baik dan benar agar tidak terjadi kesalahan interpretasi dalam me nentukan dinding lateral dan dinding septal ventrikel kiri. 16,17 Citra SPM menggunakan kamera SPECT/CT pada pasien ini menunjukan dek strokardia dengan situ inversus disertai dengan adanya iskemia luas reversibel yang melipu ti 6 segmen, melibatkan tiga pembuluh dar ah (LAD, RCA dan LCx) dengan stratifikasi risiko tinggi. Berdasarkan hasil pemeriksaan SPM tersebut, pasien kemudian menjalani pe meriksaan angiografi dan kateterisasi jantung sebagaimana penatalaksanaan PJK pada um umnya.…”