Hedén Bo, Persson Eva, Carlsson Marcus, Pahlm Olle, Arheden Håkan
Department of Clinical Physiology, Lund University Hospital, Lund, Sweden.
BMC Med Imaging. 2009 Aug 10;9:16. doi: 10.1186/1471-2342-9-16.
It is of great clinical importance to exclude myocardial infarction in patients with suspected coronary artery disease who do not have stress-induced ischemia. The diagnostic use of myocardial perfusion single-photon emission computed tomography (SPECT) in this situation is sometimes complicated by attenuation artifacts that mimic myocardial infarction. Imaging in the prone position has been suggested as a method to overcome this problem.
In this study, 52 patients without known prior infarction and no stress-induced ischemia on SPECT imaging were examined in both supine and prone position. The results were compared with cardiac magnetic resonance imaging (CMR) with delayed-enhancement technique to confirm or exclude myocardial infarction.
There were 63 defects in supine-position images, 37 of which disappeared in the prone position. None of the 37 defects were associated with myocardial infarction by CMR, indicating that all of them represented attenuation artifacts. Of the remaining 26 defects that did not disappear on prone imaging, myocardial infarction was confirmed by CMR in 2; the remaining 24 had no sign of ischemic infarction but 2 had other kinds of myocardial injuries. In 3 patients, SPECT failed to detect small scars identified by CMR.
Perfusion defects in the supine position that disappeared in the prone position were caused by attenuation, not myocardial infarction. Hence, imaging in the prone position can help to rule out ischemic heart disease for some patients admitted for SPECT with suspected but not documented ischemic heart disease. This would indicate a better prognosis and prevent unnecessary further investigations and treatment.
对于疑似冠心病但无应激性缺血的患者，排除心肌梗死具有重要的临床意义。在这种情况下，心肌灌注单光子发射计算机断层扫描（SPECT）的诊断应用有时会因模拟心肌梗死的衰减伪影而变得复杂。有人建议采用俯卧位成像来克服这一问题。
在本研究中，对52例既往无心肌梗死且SPECT成像无应激性缺血的患者进行了仰卧位和俯卧位检查。将结果与采用延迟强化技术的心脏磁共振成像（CMR）进行比较，以确认或排除心肌梗死。
仰卧位图像中有63个缺损，其中37个在俯卧位时消失。CMR显示这37个缺损均与心肌梗死无关，表明它们均为衰减伪影。在俯卧位成像时未消失的其余26个缺损中，CMR证实2个为心肌梗死；其余24个无缺血性梗死迹象，但2个有其他类型的心肌损伤。在3例患者中，SPECT未能检测到CMR识别出的小瘢痕。
仰卧位时出现但在俯卧位时消失的灌注缺损是由衰减引起的，而非心肌梗死。因此，对于一些因疑似缺血性心脏病而接受SPECT检查但未确诊的患者，俯卧位成像有助于排除缺血性心脏病。这表明预后较好，并可避免不必要的进一步检查和治疗。
