Re-evaluation of pheochromocytomas on delayed contrast-enhanced CT: washout enhancement and other imaging features

The purpose of this study was to retrospectively evaluate the enhancement washout and other imaging features of pheochromocytomas on delayed contrast-enhanced CT. Twenty-four patients with 31 pathologically confirmed pheochromocytomas were examined using unenhanced, early and delayed contrast-enhanced CT. The range of their APEW (absolute percentage of enhancement washout) or RPEW (relative PEW) values was analyzed. The other CT features including cystic or necrotic change, calcification, and hemorrhage were also determined by a pathologic correlation. Of the 31 pheochromocytomas, 10 (32%) had APEW values of 60% or less and RPEW values of 40% or less. Fourteen (45%) had APEW values >60% and RPEW values >40%. CT showed cystic or necrotic changes in 11 pheochromocytomas (35%) and calcification (10%) in 3. Nineteen pheochromocytomas showed cystic or necrotic changes on early contrast-enhanced CT, but eight of these lesions showed late enhancement on delayed contrast-enhanced CT, which pathologically corresponded to myxoid degeneration. The unenhanced CT showed hemorrhage in 23 pheochromocytomas, but the pathology examinations showed hemorrhage in 15 lesions. Many pheochromocytomas can be misdiagnosed as adenomas on CT due to the high enhancement washout values. Delayed contrast-enhanced CT can detect myxoid degeneration with late enhancement, which is seen as a cystic or necrotic change on early contrast-enhanced CT.     

肾上腺腺瘤和非腺瘤动态增强CT表现与血管生成相关性的初步研究

目的探讨肾上腺腺瘤和非腺瘤血管生成[微血管密度（MVD），血管内皮生长因子（VEGF）]特点与动态增强CT表现的相关性，以阐述其动态增强机制。方法经手术病理证实的42例46个肾上腺肿块（腺瘤23个、非腺瘤18个、增生结节5个）均行动态增强CT检查和病理学检查。首先评价肾上腺腺瘤和非腺瘤动态增强CT表现，而后分析肾上腺肿块动态增强CT表现特征[时间-密度（T-D）曲线、廓清率（Wash）]与血管生成之间的相关关系。结果腺瘤与非腺瘤间T—D曲线类型和7min延时点相对廓清率（Washr）和绝对廓清率（Washa）差异均存在统计学意义（P=0．000）。肾上腺肿块T—D曲线廓清迅速组（A、C型）与廓清缓慢组（B、D、E型）间、7min延时点Washr≥34％组与〈34％组间、Washai≥43％组与〈43％组间MVD、VEGF表达水平差异均有统计学意义（P〈0．05）。肿块廓清曲线为A、C型，和（或）Washr≥34HU，和（或）Washai≥43％组均提示为腺瘤，反之提示为非腺瘤。T—D曲线廓清迅速组、7min延时点Washri≥34％组和Washa≥143％组MVD、VEGF表达水平分别高于廓清缓慢组、〈34％组和〈43％组；由此提示动态增强CT表现特征与MVD、VEGF表达存在相关性。另一方面，腺瘤和非腺瘤间MVD和VEGF表达存在显著不同。结论MVD和VEGF可能是导致腺瘤和非腺瘤具有不同的T—D曲线类型和廓清率的主要因素之一。     

Giant congenital intrapericardial left atrial aneurysm diagnosed by contrast-enhanced computed tomography

A left atrial aneurysm is a rare cardiac anomaly. The etiology is usually congenital, but it can also occur as an acquired pathology secondary to mitral valve disease or a degenerative process. We report a case which, on routine PA chest radiography, presented as cardiomegaly with a bulge on the left cardiac contour. Further evaluation by contrast-enhanced computed tomography proved it to be caused by a large left atrial aneurysm.     

Adrenal gland and adrenal mass calcification

With the widespread use of computed tomography (CT), it is not unusual to find calcification within the adrenal glands. There are a variety of adrenal lesions that may calcify, but usually the appearance of the calcification is not specific. However, when the pattern and morphology of the adrenal calcification are combined with the other imaging features and the appropriate clinical history, the correct diagnosis may be suggested.     

Timing of exposure in angiographic computed tomography

Visualization of heart chambers or the abdominal arterial phase on one of two CT-scans was achieved in 89.4% of 169 injections (91 patients) using only 30 ml of contrast medium (370 mg iodine/ml), when the start of scanning was accurately timed at predicted bolus peak concentration. Normal arrival times and numer of transit cycles to the bolus concentration maximum in the right (RV) and left ventricle (LV) after injection of a small radionuclide bolus of technetium-99 m were related to the patient's heart rate (HR) in a group of 200 patients. For the RV, mean arrival times varied significantly between 2.31 (HR: 90–109 beats per minute) and 3.46 seconds (HR: 50–59 beats per minute), mean number of transit cycles between 4.1 and 3.5. For the LV, mean arrival times varied significantly between 6.92 (HR: 90–109 beats per minute) and 11.37 seconds (HR: 50–59 beats per minute), and the mean number of transit cycles between 11.5 and 10.7. Washout from the LV lasted between an average of 9.2 (HR: 90–109 beats per minute) and 8.5 cycles (HR: 50–59 beats per minute). Contrary to actual transit times, there was no significant difference in the number of transit heart cycles for heart rates between 60 and 109 beats per minute, so that to determine the scan starting time, the patient's cycle length (60 divided by heart rate) had only to be multiplied by the corresponding normal value of transit cycles, i.e., four for the RV, 11 for the LV, and 13 for the abdominal arteries. By applying the estimated values, the result was negative on two successive scans in only 10.6% because of failure in coordination on the part of the operators or bolus transit delays (due to severe heart failure, severe lung disease, recent thoracotomy, or small veins disease). With automatic triggering of the scanner by a timer and injector and with a flush of saline after injection, results can be further improved. Radionuclide studies supported by grant of the Internal Department of the Government of the Federal Republic of Germany     

Ureterolithiasis: classical and atypical findings on unenhanced helical computed tomography

Evaluation of patients with acute flank pain using helical computed tomography (CT) is a well-accepted, rapid, and safe procedure in the emergency setting. Various primary and secondary signs are described in the literature for evaluation of these patients. Our purpose is to demonstrate both the classical findings associated with ureteral calculi on unenhanced helical CT and atypical findings and potential pitfalls. We also provide readers with a systematic approach to interpreting unenhanced helical CT scans performed for acute flank pain. Electronic Publication     

Differentiation between tuberculosis and primary tumors in the adrenal gland: evaluation with contrast-enhanced CT

The aim of the present study is to determine imaging criteria for differentiating tuberculosis from primary tumors in the adrenal gland on contrast-enhanced CT. Non-contrast and contrast-enhanced CT features in 108 patients with adrenal tuberculosis (n=34) and primary tumor (n=74) were retrospectively assessed for the location, size, calcification and enhancement patterns. The primary tumors included 41 adenomas, 11 pheochromocytomas, 4 carcinomas, 3 lymphomas, 6 myelolipomas, 6 ganglioneuromas, 2 neurilemmomas and 1 ganglioneuroblastoma. Biochemical investigation was performed for all patients. Of the tuberculosis cases, 31 (91%) invaded with bilateral involvement, while 7 (9%) of the primary tumors invaded with bilateral involvement (P<0.001). Tuberculosis often showed calcification (20 of 34; 59%), whereas primary tumors infrequently showed calcification (6 of 74; 8%; P<0.001). Low attenuation in the center with peripheral rim enhancement was more commonly seen in tuberculosis (16 of 34; 47%) than in primary tumors (7 of 74; 9%; P<0.001). In the determination of tuberculosis, the highest sensitivity (91%) and accuracy (91%) were obtained with bilateral involvement, and the highest specificity (99%) was obtained with the contour preserved. In the determination of primary tumors using a combination of having unilateral involvement and being mass-like, the outcome was a sensitivity of 91%, specificity of 94% and accuracy of 92%. CT findings can differentiate tuberculosis from a primary tumor of the adrenal glands with high sensitivity and an acceptable specificity when combined with the endocrinological examination.     

Incidental adrenal lesions: Accuracy of quadriphasic contrast enhanced computed tomography in distinguishing adenomas from nonadenomas

Purpose

To evaluate the accuracy in distinguishing adrenal adenomas from nonadenomas by means of quadriphasic CT exam, including unenhanced (UE), arterial enhanced (AE), portal enhanced (PE) and 5-min delayed enhanced (DE) CT scans.

Methods

This retrospective study had institutional review board approval; the need for informed consent was waived. From September 2007 to September 2009, 104 adrenal masses were evaluated in 87 patients (49 M, 38 F, mean age 58.4 years) undergoing UE, AE (35-s delay), PE (80-s delay) and DE (5-min delay) CT scans. The mean adrenal attenuation during all imaging phases was measured by two readers. The accuracy values of absolute unenhanced attenuation (UE), absolute wash-out (AWO), relative percentage wash-out (RPWO) and percentage enhancement wash-out (PEW) were assessed by using receiver operator curves (ROC) analysis. The overall accuracy of the quadriphasic protocol and other triphasic protocols were evaluated. A value of p ≤ 0.05 was considered significant.

Results

The accuracy in characterizing adrenal lesions was 86.5% (90/104) for UE attenuation (≤10 HU threshold), 90.1% (82/91) for RPWO (≥30% threshold), 85.7% (78/91) for AWO (≥12 HU threshold) and 83.5% (76/91) for PEW (≥30% threshold), respectively. Quadriphasic CT (accuracy 97.1%, 101/104) performed better than triphasic CT including only AE scan (efficiency 90.0%, 94/104; p = 0.011) and triphasic CT including only PE scan (efficiency 96.1%, 100/104; p = 0.025).

Conclusion

Quadriphasic CT protocol including 5-min DE scan may be used to characterize incidentally detected adrenal masses. RPWO represented the best wash-out parameter for characterizing adrenal lesions.     

肾上腺结核的增强CT表现特征与临床病程的相关性

目的探讨肾上腺结核的增强CT表现特征与临床病程的相关性，以提高该病的影像诊断水平。方法经临床证实的肾上腺结核30例，在CT强化图像上观察肾上腺的位置、大小、形态、密度以及强化特征，并结合临床和病理资料加以分析，采用Cochran Armitage趋势检验进行统计分析。结果肾上腺结核累及双侧共27例（90．0％），单侧3例（10．0％）。肾上腺肿块样增大13例，轻度或中度增大17例，轮廓仍保持完整。肾上腺增大密度均匀2例（6．7％），不均匀增大28例（93．3％）。周边强化16例（53．3％），钙化17例（56．7％）。经抗结核治疗后的6例复查CT示，5例双侧增大的肾上腺体积缩小或恢复正常，其内低密度消失，新出现点状钙化2例。钙化多见于临床后期，17例钙化中，病程〉12个月者10例，存在随病程增长而递增的分布趋势（x^2=7．47，P〈0．05），而周边强化则多见于临床早期，16例中有11例临床病程≤12个月，存在随病程增长而递减的分布趋势（x^2=6．60，P〈0．05）。结论肾上腺结核CT具有特征性表现，与临床病程存在一定的相关性，为临床治疗及疗效判断提供指导。     

Diagnosis of sellar and parasellar lesions by computed tomography

Summary Suspected lesions in and around the sella were examined by CT in 129 cases. The diagnostic accuracy and various technical aspects of the method are described. The mean attenuation and enhancement after administration of contrast material are evaluated in craniopharyngiomas, chromophobe adenomas, meningiomas, aneurysms, dermoid cysts, an arachnoid cyst and a glioma. The choice of collimator and its use in relation to sellar dimensions, particularly the sellar depths, are emphasized.     

肾上腺少见肿瘤的CT表现及其病理基础

目的探讨肾上腺少见肿瘤的CT表现特征与病理的相关性,以提高诊断水平。资料与方法对18例经手术病理证实的少见肾上腺肿瘤进行回顾性分析,包括肾上腺节细胞神经瘤5例,髓性脂肪瘤4例,淋巴瘤3例,囊肿、神经鞘瘤各2例以及神经节母细胞瘤、畸胎瘤各1例。在CT图像上,观察病变的位置、大小、形态、密度、内部结构及其与周围结构的关系。结果肾上腺节细胞神经瘤CT表现为均匀软组织密度肿块,1例有点状钙化。髓性脂肪瘤为以脂肪密度为主的肿块。淋巴瘤为软组织密度肿块。良性神经鞘瘤为软组织肿块,有囊变及钙化;恶性神经鞘瘤也为软组织肿块,内见坏死区,伴淋巴结转移。囊肿呈水样密度,壁薄光整,1例有囊壁钙化。神经节母细胞瘤为密度不均匀软组织肿块,内见坏死灶,伴周围淋巴结肿大。畸胎瘤为含钙化、脂肪及软组织成分的肿块。结论CT可揭示肾上腺少见肿瘤的病理基础,它们存在一定的影像表现特点,CT是临床上最常用的影像学检查方法。     

Adrenal masses: the value of additional fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in differentiating between benign and malignant lesions

Objective  To investigate whether integrated fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) can differentiate benign from adrenal malignant lesions on the basis of maximum standardized uptake value (SUV_max), tumor/liver (T/L) SUV_max ratio, and CT attenuation value (Hounsfield Units; HU) of unenhanced CT obtained from FDG-PET/CT data. Methods  We studied 30 patients with 35 adrenal lesions (16 adrenal benign lesions, size 16 ± 5 mm, in 15 patients; and 19 adrenal malignant lesions, 24 ± 12 mm, in 15 patients) who had confirmed primary malignancies (lung cancer in 23 patients, lymphoma in 2, esophageal cancer in 2, hypopharyngeal cancer in 1, prostate cancer in 1, and 1 patient in whom lesions were detected at cancer screening). All patients underwent PET/CT at 1 h post FDG injection. Diagnosis of adrenal malignant lesions was based on interval growth or reduction after chemotherapy. An adrenal mass that remained unchanged for over 1 year was the standard used to diagnose adrenal benign lesions. Values of FDG uptake and CT attenuation were measured by placing volumetric regions of interest over PET/CT images. Adrenal uptake of SUV_max ≥ 2.5 was considered to indicate a malignant lesion; SUV_max < 2.5 was considered to indicate a benign lesion. In further analysis, 1.8 was employed as the threshold for the T/L SUV_max ratio. Unenhanced CT obtained from PET/CT data was considered positive for adrenal malignant lesions based on a CT attenuation value ≥ 10 HU; lesions with a value < 10 HU were considered adrenal benign lesions. Mann–Whitney’s U test was used for statistical analyses. Results  SUV_max in adrenal malignant lesions (7.4 ± 3.5) was higher than that in adrenal benign lesions (2.1 ± 0.5, p < 0.05). The CT attenuation value of adrenal malignant lesions (27.6 ± 11.9 HU) was higher than that of adrenal benign lesions (10.1 ± 12.3 HU, p < 0.05). In differentiating between adrenal benign and malignant lesions, a CT threshold of 10 HU corresponded to a sensitivity of 57%, specificity of 94%, accuracy of 74%, positive predictive value of 92% and negative predictive value of 65%. An SUV_max cut-off value of 2.5 corresponded to a sensitivity of 89%, specificity of 94%, accuracy of 91%, positive predictive value of 94% and negative predictive value of 88%. The T/L SUV_max ratio was 1.0 ± 0.2 for adrenal benign lesions and 4.5 ± 3.0 for adrenal malignant lesions. And T/L SUV_max ratio cut-off value of 1.8 corresponded to a sensitivity of 85%, specificity of 100%, accuracy of 91%, positive predictive value of 100% and negative predictive value of 83%. Conclusions  FDG-PET/CT with additional SUV_max analysis improves the diagnostic accuracy of adrenal lesions in cancer patients.     

Diagnostic value of the delayed phase image for iso-attenuating pancreatic carcinomas in the pancreatic parenchymal phase on multidetector computed tomography

Purpose

To assess the value of the delayed phase (DP) in pancreatic carcinomas which appear iso-attenuating in the pancreatic parenchymal phase (PPP).

Materials and methods

Fifty-seven preoperative MDCT studies of pancreatic carcinomas were retrospectively reviewed. The size of the tumors, and the Hounsfield unit (HU) of the tumors and pancreatic parenchyma were measured. The tumor-to-pancreas contrast (TPC: |HU [tumor] − HU [normal pancreas]|) was calculated.

Results

Eight cases (14.0%) showed iso-attenuation and 49 showed hypo-attenuation in the PPP. The DP images revealed seven of eight (87.5%) iso-attenuating tumors to be hyper-attenuating. The size of iso-attenuating tumors was smaller than that of hypo-attenuating tumors (mean ± S.D.: 12.4 ± 4.8 mm vs. 30.3 ± 9.0 mm, p < 0.0001). In hypo-attenuating tumors, TPC in the PPP (60.2 ± 24.6 HU) was higher than those in the portal venous phase (PVP, 40.5 ± 23.0 HU, p < 0.0001) and DP (18.3 ± 11.8 HU, p < 0.0001). In contrast, in iso-attenuating tumors, TPC in the DP (26.0 ± 4.9 HU) was higher than those in the PPP (9.2 ± 3.7 HU, p = 0.0003) and PVP (7.1 ± 4.7 HU, p = 0.001) phases.

Conclusion

The DP image is helpful in depicting small iso-attenuating pancreatic carcinomas as slightly hyper-attenuating tumors.     

Acute coronary syndrome on non-electrocardiogram-gated contrast-enhanced computed tomography

It is not rare for acute coronary syndrome (ACS) patients to present with symptoms that are atypical, rather than chest pain. It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who present with atypical symptoms, normal initial biomarkers of myocardial necrosis, and normal or nondiagnostic electrocardiograms (ECGs). Although cardiac CT allows for assessments of coronary artery stenosis as well as myocardial perfusion defect in patients with suspected ACS, it requires ECG gating and is usually performed with high-performance multislice CT for highly probable ACS patients. However, several recent reports have stated that ACS is detectable by myocardial perfusion defects even on routine non-ECG-gated contrast-enhanced CT. A growing number of contrast-enhanced CT scans are now being performed in emergency departments in search of pathologies responsible for a patient’s presenting symptoms. In order to avoid inappropriate management for this life-threatening event, clinicians should be aware that myocardial perfusion defect is more commonly detectable even on routine non-ECG-gated contrast-enhanced CT performed in search of other pathologies.     

Differentiation of adrenal tumors in patients with hepatocellular carcinoma: Adrenal adenoma versus metastasis

Objective

To investigate whether computed tomography (CT) attenuation test for differential diagnosis of adrenal nodule is applicable in patients with hepatocellular carcinoma (HCC) which shows similar image characteristics to adrenal adenoma.

Materials and methods

This retrospective study was approved by our institutional review board, and the requirement for informed consent from study patients was waived. Searching picture archiving and communication system, we identified 3678 patients with HCC who underwent upper abdominal unenhanced CT scans between April 2002 and March 2010, and 114 adrenal nodules (39 adenomas and 75 metastases) were included for analysis. Ten nodules were confirmed pathologically while 104 had imaging diagnosis (enlarged or emerged during the study period). Size, CT number, and the internal characteristics of the lesions were recorded.

Results

Mean CT numbers of adrenal adenomas were significantly lower than those of metastases (P < 0.0001, t-test) on unenhanced CT. Thresholds of 17 and 33 Hounsfield units (HU) provided the following sensitivity, specificity, and accuracy: 46.2%, 100%, and 81.6% at 17 HU, and 94.9%, 89.3%, and 91.2% at 33 HU, respectively. The area under receiver operating characteristic curve for the CT number test was 0.96. Metastases were significantly larger than adrenal adenoma (P = 0.009, t-test). However, the accuracy of testing using mass size was 64.0% at most. All adenomas and metastases were depicted as homogeneous masses with the exception of two metastases that presented as heterogeneous masses (necrotic or lipomatous).

Conclusion

Adrenal adenomas can be differentiated from HCC metastases using CT number on unenhanced CT.     

Bilateral reversible thalamic lesions on computed tomography

Summary Bilateral approximately symmetrical hypodense areas located in the thalamus were encountered in two patients who recovered clinically. Regression of the lesions could be observed on CT. The clinical symptoms corresponded to the thalamic location. Since these two patients recovered, no autopsy material is available to prove the nature of the causative lesion, although the etiology is most probably inflammatory.     

Comparison of unenhanced and contrast-enhanced spiral CT for assessing interval change in patients with colorectal liver metastases

RATIONALE AND OBJECTIVES: The purpose of this study was to determine whether the interval change in hepatic colorectal metastases as assessed with serial computed tomographic (CT) scans without contrast material enhancement differs from that as assessed using serial, portal dominant phase, contrast-enhanced CT scans. MATERIALS AND METHODS: Unenhanced and contrast-enhanced abdominal CT scans were obtained in 28 patients. Three radiologists separately reviewed serial unenhanced and contrast-enhanced studies to assess the interval change in liver metastases. These radiologists recorded total number of lesions, bidimensional measurements of the largest lesions (as many as three), and overall impressions regarding the interval change (none, worse, or better). RESULTS: Among the 84 judgments (28 patients x 3 radiologists), comparisons of unenhanced and contrast-enhanced CT studies were concordant in 60 assessments (71%). Nineteen (23%) showed mild disagreement. Of these, contrast-enhanced CT studies demonstrated disease stability when unenhanced CT studies demonstrated otherwise in 11 judgments, whereas unenhanced CT studies demonstrated stability when contrast-enhanced CT studies demonstrated otherwise in eight assessments. Furthermore, of the five marked disagreements, two resulted from a conclusion of interval improvement on unenhanced CT studies and a conclusion of interval worsening on contrast-enhanced CT studies, whereas three demonstrated the opposite. Neither set of serial CT studies systematically resulted in under- or overestimation of disease progression (McNemar Q test, P < .25). CONCLUSION: The authors found no consistent pattern to demonstrate that serial unenhanced or contrast-enhanced CT studies resulted in over- or underestimation of disease progression.     

Positron emission tomography/computed tomography for staging and restaging of head and neck cancer: comparison with positron emission tomography read together with contrast-enhanced computed tomography

This retrospective study aimed to describe the differences between image readings done with combined positron emission tomography/computed tomography (PET/CT) and PET read together with contrast-enhanced CT (ceCT) in patients with squamous cell carcinoma of the head and neck. In 46 patients, no differences were found between the two readings for assessing infiltration of adjacent structures (P=.63), transgression of the midline (P=.67), lymph node involvement (P=.32), and T- and N stage. PET/CT and PET read together with ceCT have comparable diagnostic yield.     

First-pass perfusion computed tomography: Initial experience in differentiating adrenal adenoma from metastasis

Objective

To differentiate adrenal adenoma from metastasis in patients using perfusion computed tomography (PCT) imaging.

Methods

Thirty-two patients with adrenal masses underwent first-pass PCT imaging. Of these patients, twenty-one were diagnosed with adrenal adenoma, and the others with metastases. Perfusion maps of blood volume (BV), blood flow (BF), mean transit time (MTT) and permeability surface-area production (PS) were generated with an Advantage Windows workstation using the CT perfusion 3.0 software (General Electric Medical Systems, Milwaukee, WI). Histopathologic sections immunostained for CD34 were quantitatively evaluated for microvessel density (MVD).

Results

The perfusion parameters such as BV, BF and PS were statistically significant different between the two groups, with adenomas showing higher mean BV (12.18 versus 3.86), BF (97.51 versus 45.99) and PS (21.73 versus 10.93) compared with metastases (p < 0.05). For BV, a cutoff point of 7.30 was found to have a sensitivity of 95.2% and a specificity of 100% to differentiate between adenoma and metastasis. The sensitivity and specificity were 81.0 and 80.0%, respectively, for BF with a cutoff point of 71.96; and 85.7 and 86.7%, respectively, for PS with a cutoff point of 12.70 to differentiate adenoma and metastasis. A comparison of MVD counts from adenomas with those from metastases showed a significant difference (p < 0.05). However, no significant differences were observed in the four perfusion parameters and MVD between lipid rich and lipid poor adenomas.

Conclusion

PCT may be useful for evaluating the neovascularization of adrenal masses and differentiating adenoma from metastasis on the basis of PCT parameters. Adenomas show higher BV, BF and PS compared with metastases. According our data, the optimal threshold BV is 7.30, resulting in a sensitivity of 95.2% and a specificity of 100% for the differentiation of adenoma from metastasis. Adrenal adenomas have similar hemodynamic profiles, which are apparently independent of the lipid content of an adenoma.     

Washout curves from myocardial infarctions in dogs,studied by contrast-enhanced computed tomography

Experimental myocardial infarctions appear on CT scans as areas of mixed high and low densities. As the healing of the infarction proceeds, the low-density areas gradually decrease in size and disappear completely within 5 weeks. Healed infarctions appear as a high-density area only. In order to explore the contrast medium transport in the infarcted area, washout curves were constructed from the infarct components, the normal myocardium, and the left ventricular cavity at regular intervals over a period of 145 days. All regions except the low-density zones showed continuous decrease in density during the washout. The low-density zones showed gain in density during the first 10 to 15 min of washout, probably representing slow diffusion of contrast medium into the necrotic tissue. During the first 5 weeks of the healing process, the washout curve from the low-density zones gradually became similar and ultimately conformed to the other curves, concomitant with the ongoing neovascularization of the lesion. This work was supported in part by National Institute of Heart, Blood and Lung, Grant #HL 33762