Noncardiac Findings in Cardiac Imaging With Multidetector Computed Tomography

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1 Journal of the American College of Cardiology Vol. 48, No. 2, by the American College of Cardiology Foundation ISSN /06/$32.00 Published by Elsevier Inc. doi: /j.jacc Noncardiac Findings in Cardiac Imaging With Multidetector Computed Tomography Yoshinobu Onuma, MD,* Kengo Tanabe, MD, PHD,* Gaku Nakazawa, MD,* Jiro Aoki, MD,* Hiroyoshi Nakajima, MD, PHD,* Kenji Ibukuro, MD, Kazuhiro Hara, MD, FACC* Tokyo, Japan OBJECTIVES We investigated the frequency of the noncardiac findings in cardiac imaging with multidetector computed tomography (MDCT). BACKGROUND Multidetector computed tomography is an accepted new tool to evaluate the heart. In cardiac MDCT scans, organs other than the heart are also irradiated, but usually not assessed. METHODS A total of 503 patients underwent cardiac imaging with 16- or 64-slice MDCT. Cardiologists assessed the heart, while radiologists reviewed the other organs. RESULTS A total of 346 new, noncardiac findings were identified in 292 patients (58.1%). A total of 114 patients (22.7%) had clinically significant findings including 4 cases of malignancy (0.8%). CONCLUSIONS There were a significant number of noncardiac findings in cardiac MDCT. To avoid missing clinically important findings, physicians who analyze cardiac MDCT scan either radiologists or cardiologists should carefully evaluate all the organs irradiated in the scan. (J Am Coll Cardiol 2006;48:402 6) 2006 by the American College of Cardiology Foundation Multidetector computed tomography (MDCT) with high temporal and spatial resolution is emerging as a noninvasive diagnostic technique to visualize the heart. It is now accepted as a useful modality to detect coronary stenoses (1 10) and coronary plaques (11), to assess calcification of the coronary arteries (12), remodeling of coronary atherosclerotic lesions (13), anatomy of the pericardium (14), and size and function of the ventricles (15,16). Because of the growing number of scanners, these examinations will be See page 407 performed with increasing frequency. This versatile modality is expected to diagnose not only coronary artery disease but also other diseases causing chest pain such as aortic dissection (17,18) and pulmonary embolism (19,20). As all chest organs including portions of the great vessels, lungs, chest wall, spine, liver, and gall bladder are also irradiated during the cardiac MDCT scans, noncardiac diseases unrelated to chest symptoms might be detected. However, the incidence of abnormal findings in these organs in cardiac MDCT has not been fully investigated. We examined the frequency of noncardiac findings in a series of patients undergoing cardiac MDCT. As to the patients with significant noncardiac findings, we reviewed how these findings were followed up in the 6 months after cardiac MDCT. METHODS The study group consisted of 503 consecutive patients with suspected coronary artery disease who underwent diagnostic From the *Division of Cardiology, Mitsui Memorial Hospital, Tokyo, Japan; and the Division of Radiology, Mitsui Memorial Hospital, Tokyo, Japan. Manuscript received October 19, 2005; revised manuscript received March 6, 2006, accepted April 4, cardiac MDCT between July 1, 2004, and July 14, 2005, at a single center. Data acquisition. Multidetector computed tomography data were acquired with a 16-slice MDCT scanner (SO- MATOM Sensation Cardiac 16, Siemens, Forchheim, Germany) between July 2004 and November 2004 and a 64-slice MDCT scanner (SOMATOM Sensation Cardiac 64, Siemens) between November 2004 and July Patients were scanned in the supine position from the level of the pulmonary arteries through the base of the heart. Patients with a history of coronary artery bypass graft (internal mammary artery or gastroepiploic artery) were scanned widely from the level of the subclavian arteries through the level of the celiac trunk. According to previous reports (4,10), we performed a non-enhanced scan primarily for calcium scoring and an enhanced scan for MDCT angiogram. A contrast-enhanced scan was obtained using 60 to 100 ml of contrast injected through the antecubital vein at 4.5 ml/s, followed by a 30-ml saline chaser. The scan parameters in the 16-MDCT scanner were: mm collimation; rotation time 370 ms, table feed 3.0 mm/ rotation; tube voltage 120 mv; effective ma 550. The scan parameters in the 64-MDCT scanner were: mm collimation; rotation time 330 ms, table feed 3.8 mm/ rotation; tube voltage 120 mv; effective ma 770. Enhanced datasets were reconstructed for assessment of coronary stenosis at 320 to 420 ms before the R-wave, and adjusted individually so that the end of the reconstruction period was positioned at the peak of the P-wave on the electrocardiogram (21). One dataset was reconstructed with a small field of view (FOV) tightly confined around the heart. A second dataset was reconstructed with a large FOV to include the entire chest in each cross section with a slice thickness of 5 mm. Analysis. All scans were at first analyzed by 3 cardiologists. Images with a large FOV were reviewed by 4 experienced

2 JACC Vol. 48, No. 2, 2006 July 18, 2006:402 6 Onuma et al. Noncardiac Findings in Cardiac MDCT 403 radiologists in standard mediastinal windows (350 W/50C) and lung windows (1,400 W/ 600C). All abnormalities and patients with significant abnormal findings were identified. The number of new noncardiac findings in each organ was counted, and significant findings were defined as abnormalities that required additional follow-up or further investigation. Medical records were reviewed to check the clinical follow-up, subsequent imagings, or surgical procedures of noncardiac abnormalities in the 6 months after cardiac MDCT. RESULTS Abbreviations and Acronyms CT computed tomography EBCT electron-beam computed tomography FOV field of view MDCT multidetector computed tomography Clinical characteristics of the patients are summarized in Table 1. There was no evidence of acute coronary syndrome. A total of 420 patients (83.5%) were symptomatic. Sixtyfive patients (12.9%) were current smokers, and 197 patients (39.2%) were former smokers. In the cardiac analysis, 238 patients (47.3%) had a positive result for cardiac disease. In the noncardiac analysis, a total of 346 noncardiac findings were identified in 292 (58.1%) of 503 patients. Table 2 presents the organs and structures with noncardiac findings. Of 420 symptomatic patients, cardiac disease was detected in 219 patients. Of the remaining 201 patients, 32 patients were diagnosed with noncardiac findings, which could be the cause of symptoms. A total of 114 patients (22.7%) had significant noncardiac pathology requiring clinical or radiological follow-up. Seventy-five patients underwent further imaging or investigations, and 18 patients had therapeutic consequences during 6 months of follow-up. Table 3 shows the number of Table 1. Clinical Characteristic of the Patients Variable n (%) Patients 503 Age, yrs Male gender 382 (76) History of PCI 144 (29) History of bypass graft operation 122 (24) Diabetes 91 (18) Hypertension 277 (55) Family history of CAD 124 (25) Hemodialysis 26 (5) Current smoker 65 (13) Former smoker 197 (39) Clinical presentation Anginal symptom 420 (83) Asymptomatic, complete LBBB 6 (1) Asymptomatic, inconclusive exercise stress test results 77 (15) Values are n (%) or mean SD. CAD coronary artery disease; LBBB left bundle branch block; PCI percutaneous coronary intervention. patients with diagnostic and therapeutic consequences. Of the other 39 patients, 26 patients were followed without any imaging workup. Follow-up information could not be obtained from outside hospitals in 12 patients. One patient died from brain hemorrhage, which was unrelated to the noncardiac findings. Imaging workup included 24 computed tomography (CT) scans, 2 magnetic resonance imaging examinations, 2 mammograms, 3 sonograms, and 43 conventional radiographs. The time between cardiac MDCT and follow-up imaging studies ranged from 1 to 178 days. Malignancies were revealed in 4 patients (0.80%). Two were found to have adenocarcinoma of the lung (Fig. 1). Both patients were treated surgically. The other 2 patients had malignancy of the breast. One was diagnosed as intraductal carcinoma of the breast (Fig. 2) and surgically treated. The other proved to be angiosarcoma, and the patient died from repetitive hemorrhage of the malignancy. DISCUSSION In this study, we found that 58.1% of the patients referred for cardiac MDCT scan had noncardiac findings, 22.7% of the patients were found to have significant noncardiac pathology requiring additional work-up, and 3.6% had therapeutic consequences. During 6 months of clinical follow-up, 4 cases of malignant disease were revealed. Routine cardiac MDCT is performed by scanning the heart from bifurcation of the pulmonary artery to the left ventricular apex with or without a non-enhanced scan for assessment of calcification. Consequently, images are reconstructed to focus on the heart in synchronization with the diastolic phase. In the process, we can freely adjust the FOV the area in which a raster with a predefined number of pixels is arranged from the raw data without additional radiation exposure, because the entire content within the boundaries of the gantry is scanned and available. For cardiac imaging, FOV was confined to be as small as possible to achieve best resolution and ranged from 16 to 25 cm 2. These images included little of the lung or the other chest organs, although all chest organs were irradiated. Besides images for cardiac analysis, we made another set of images with a large FOV to evaluate the peripheral chest. This method is not universal, but we think it could be beneficial to evaluate all organs irradiated in the scan. For patients with chest symptoms, pleural or aortic diseases could be differentiated in the same scan. Of 201 symptomatic patients in whom coronary artery disease was ruled out, 32 patients were diagnosed to have noncardiac findings, which could cause anginal symptoms. In these patients, further diagnostic imaging workup was not necessary. In addition, asymptomatic malignancies could be detected. In this study, 3 cases of malignancies were revealed in an asymptomatic and surgically treatable stage. If the peripheral chest had not been properly evaluated in cardiac

3 404 Onuma et al. JACC Vol. 48, No. 2, 2006 Noncardiac Findings in Cardiac MDCT July 18, 2006:402 6 Table 2. Organs and Structures With Noncardiac Findings Organ Structure Findings/Diagnosis n Abdominal organs Liver Cyst 31 Fatty liver 4 Hemangioma 2 Gull bladder Cholelithiasis 18 Spleen Calcification 2 Kidney Cyst 13 Nephrolithiasis 2 Lung Parenchyma Infiltrate 31 Post-inflammatory change 15 Nodules 1.0 cm 12 Non-calcified nodule 1.0 cm 49 Calcified nodule 1.0 cm 23 Emphysema 18 Atelectasis 18 Bulla 30 Fibrosis 3 Lymph node Swelling 5 Bronchi Ectasia 2 Pleura Effusion 20 Calcification 4 Thickening 16 Pulmonary artery Dilation 1 Mediastinal organs Mediastinitis 2 Lymph nodes Swelling 1 Esophagus Hernia 1 Aorta Aneurysm 7 Dissection 1 Spinal column Hemangioma 1 Scoliosis 1 Thyroid Nodule 3 Cyst 3 Atrophy 1 Mammary gland Nodule 3 Miscellaneous Extrapleural mass 1 Abnormal origin of the subclavian artery 1 MDCT, they may have been diagnosed at a later stage. Evaluating noncardiac findings may be important to prevent significant morbidity and mortality. There are no published data on the prevalence of noncardiac abnormalities in cardiac MDCT studies, although several studies of electron-beam computed tomography (EBCT) cardiac scans have been published (22,23). Hunold et al. (23) investigated 1,812 patients undergoing EBCT and demonstrated about the same frequency of noncardiac findings (53%) as the present study (58%). In a study by Horton et al. (22), of 1,326 consecutive patients with EBCT, significant noncardiac Table 3. Diagnostic and Therapeutic Consequences in the Patients With Significant Noncardiac Findings During the 6 Months After the MDCT Scan Significant Noncardiac Findings No. of Patients Patients With Further Investigations Patients With Therapeutic Consequences Non-calcified pulmonary nodules 1 cm Pulmonary nodules 1 cm Pulmonary infiltration Pleural effusion Extra-pleural mass Breast abnormality Lymph node swelling Dissecting aorta Aortic aneurysm Mediastinitis Thyroid nodule 3 2 0

4 JACC Vol. 48, No. 2, 2006 July 18, 2006:402 6 Onuma et al. Noncardiac Findings in Cardiac MDCT 405 Figure 1. The arrow indicates a nodule in the right lung of a 75-year-old woman with suspected coronary artery disease who underwent a 64-slice multidetector computed tomography scan. The nodule was pathologically proved to be adenocarcinoma. findings that required clinical or radiological follow-up were observed in 7.8%. In contrast, the present study identified significant noncardiac findings in 22.7%, in which pulmonary nodules and aortic disease were observed more frequently. The higher incidence of pulmonary nodules in our cohort is partly related to a larger number of former or current smokers. Fifty-two percent of the patients were former or current smokers in our study, while only 25% were former or current smokers in the study by Horton et al. (22). The risk of coronary artery disease decreases promptly after smoking cessation (24), while the risk of lung carcinoma does not. The incidence of lung cancer correlates with the amount of cigarettes smoked (25). Therefore, our cohorts were considered to be at a higher risk of lung carcinoma. Contrast enhancement may have contributed to frequent detection of aortic disease in our study, while Horton et al. (22) performed EBCT scans without contrast. Furthermore, the high resolution of MDCT may allow accurate interpretation of pathology in the other chest organs. Our study detected 2 cases of lung cancer (0.4%) with 6 months of follow-up. In studies of CT screening for lung cancer, frequency of noncalcified nodules in baseline screening ranges from 12% to 46%, that of lung cancer ranges from 0.4% to 2.7% (26 31). Nawa et al. (28) reported that 0.44% of the patients undergoing low-dose spiral CT scan demonstrated lung cancer and that 26.8% had non-calcified pulmonary nodules in a population quite similar to ours. The population of that study included 62% who were former or current smokers, while our population included 53%. The prevalence of lung cancer in that study (0.44%) was the same as in our study (0.4%). The limitations of our study are as follows. First, the time of clinical follow-up was relatively short. For example, the only way to make certain that a pulmonary nodule is benign is to follow it up to demonstrate stability over years unless it is surgically resected. We might have underestimated the significance of the noncardiac findings. Second, a cost/ efficacy analysis was not performed in the present study. A prospective, controlled study is necessary to elucidate cost/ efficacy of evaluating noncardiac findings in cardiac MDCT. In conclusion, a number of clinically significant noncardiac findings might have been missed in conventional cardiac MDCT scans. Although a small percent of the findings resulted in therapeutic consequences, some were important, including asymptomatic malignancies. Cardiologists are familiar with anatomy of the heart but are usually not trained to perform radiological diagnosis of the other thoracic organs. For a cardiologist analyzing cardiac MDCT scans, it is essential to collaborate with radiologists to avoid missing significant findings. Physicians who analyze cardiac MDCT scans either radiologists or cardiologists should carefully evaluate all the organs in the scan. Figure 2. The arrow indicates a nodule in the left breast of a 62-year-old woman who underwent a 16-slice multidetector computed tomography scan. The nodule was surgically resected and proved to be intraductal carcinoma.

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