목적: 토끼에서 유발된 심근 경색의 시기별 (다중검출기전산화단층촬영(Multi-detector row CT, 이하 MDCT)) 소견과 전층 침범 진단의 정확도를 평가하고, MDCT와 병리소견 간의 연관성을 알아보고자 하였다. 대상과 방법: 관상동맥을 결찰한 15마리 토끼 중 심근 경색이 발생한 10마리의 토끼에서 시간 경과에 따라 초급성기, 급성기 및 만성기에 조영제를 주입하여 MDCT를 시행하였다. 측정기의 폭 조절(collimation)은 12 × 0.75-mm, 회전 시간은 420 ms로 하고, 후향적 심장 동조화를 시행하였으며, 조영제 주입으로부터 1분과 6분의 초기와 지연기에 심장의 횡단면 영상을 얻었다. MDCT 시행 직후, 토끼를 희생시켜 triphenyltetrazolium chloride (TTC) 염색 표본을 만들고, MDCT와 TTC 표본 간의 심근 경색의 전 층 침범의 일치도를 계산하고, 현미경 검사를 시행하였다. 결과: 심근 경색의 MDCT 소견은 초급성기에는 고음영과 저음영이 섞여 보였고, 급성기에는 초기 영상에서 저음영이, 지연기 영상에서 저음영에 테두리 조영증강이 동반되었으며, 만성기에는 지연기 영상에서 조영증강을 보이는 반흔으로 나타났다. 전 층 침범의 일치도는 초급성기에는 낮았고 (k = 0.380), 급성기의 초기 영상 및 만성기의 지연기 영상에서 높았다 (k = 0.865, 0.858). 현미경 소견에서 초급성기에서 만성기로 갈수록 괴사 심근 주변에 염증반응과 수복반응이 진행되었다. 결론: 심근 경색의 MDCT 소견은 경색의 시간 경과에 따라 다른 양상으로 보이며, 이는 동반되는 염증 및 수복 반응의 정도를 반영하는 것으로 보인다. 또한, 경색 범위의 진단에서, 초급성기에는 MDCT가 유용하지 않고, 급성기에는 초기 영상이, 만성기에는 지연기 영상이 유용하였다.
Purpose: This study was designed to evaluate the imaging findings and the diagnostic accuracy for determining the transmural extent of a myocardial infarct (MI) in rabbits with the use of multidetector row CT (MDCT) according to the infarct age, and we determined the radiological and pathological correlation. Materials and Methods: MIs were demonstrated in 10 of 15 rabbits in which ligation of the left coronary arteries was performed. The cardiac scans were obtained according to the infarct age (hyperacute (within 24 hours), acute (24 hours to seven days) or chronic (eight weeks)) by using a 16-MDCT scanner in the contiguous transverse plane with 12×0.75 mm collimation, 420 ms rotation and retrospective ECG-gating. Early and late scans were obtained at one minute and six minutes, respectively, after intravenous contrast injection. The rabbits were sacrificed according to the infarct age. Slices of the cardiac specimens stained with triphenyltetrazolium chloride (TTC) and the MDCT images were evaluated for scoring the transmural extent of the MIs. The agreement of the scores between the MDCT images and TTC-stained specimens was statistically analyzed. The radiological and pathological correlation was determined for the specimens and the MDCT images. Results: The presence of an infarcted myocardium in the hyperacute phase was demonstrated as a mixed low and high-attenuation area on the early and late scans. In the acute phase, a low-attenuation area was seen on the early scan and a low-attenuation area with enhancement along the endocardial and pericardial sides was seen on the late scan. In the chronic phase, a high-attenuation area was seen on the late scan. There was fair agreement for the scores of the MDCT scan in hyperacute MI (kappa value = 0.380) and excellent agreement of the early scan in acute MI and the late scan of chronic MI (kappa value = 0.865 and 0.858, respectively). A pathological examination of the TTC-unstained areas of the MI specimens demonstrated the presence of necrosis of myocardial cells and the increased inflammatory infiltrates and repair process surrounding the damaged myocytes, according to the infarct age. Conclusion: The MDCT findings of MI were various according to the infarct age, which might be caused by the degree of the inflammatory and repair process. For diagnosing the transmural extent of MI, the early MDCT scan was useful for the acute MI and the late scan was useful for the chronic MI. However, MDCT was not useful for diagnosing the transmural extent of the hyperacute MI.
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