Renal blood flow measurement with contrast-enhanced harmonic ultrasonography: evaluation of dopamine-induced changes in renal cortical perfusion in humans

BACKGROUND

An accessible non-invasive method for evaluating renal regional blood flow in real time is highly desirable in the clinical setting. Recent progress in ultrasonography with microbubble contrast has allowed quantification of regional blood flow in animal models.

AIMS

Goal ofthis study was to establish a convenient contrast--enhanced harmonic ultrasonography (CEHU) method for evaluating renal cortical blood flow in humans.

METHODS

We carried out intermittent second harmonic imaging in 9 healthy volunteers. Pulse interval was progressively decreased from 4 s - 0.2 s during continuous venous infusion of the microbubble contrast agent.

RESULTS

Pulse interval versus CEHU-derived acoustic intensity plots provided microbubble velocity (MV) and fractional vascular volume (FVV) during renal cortical perfusion in humans. Low-dose dopamine infusion (2 microg/min/kg) resulted in a significant increase in MV which correlated well with the increase in total renal blood flow (RBF) determined by a conventional study of p-aminohippurate clearance (C(PAH)) (r = 0.956, p < 0.0001). Although FVV was not significantly increased, alterations in CEHU-derived renal cortical blood flow calculated by the products of MV and FVV were also correlated with alterations in total RBF (r = 0.969, p < 0.0001). Thus, low-dose dopamine infusion increases renal cortical blood flow observed in CEHU, mainly by increasing MV.

CONCLUSIONS

The present study shows that renal cortical blood flow in humans can be measured non-invasively by CEHU and that CEHU can be used for quantitatively evaluating changes induced by a therapeutic agent such as dopamine in flow velocity and in FVV.

Lower mortality in patients with the DD genotype of the angiotensin-converting enzyme gene after acute myocardial infarction

OBJECTIVE

The angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been associated with different serum ACE concentrations and cardiac ACE activity. We assessed whether the ACE gene I/D polymorphism influenced cardiac mortality in Japanese patients with acute myocardial infarction.

METHODS AND RESULTS

The ACE gene I/D polymorphism was determined in 441 consecutive patients with a first myocardial infarction. There were 69 patients (16%) with the DD genotype, 194 patients (44%) with the ID genotype, and 178 patients (40%) with the II genotype. During a mean follow-up of 9.4 months, there were 49 cardiac deaths (DD, n = 4; ID, n = 26; II, n = 19). The DD genotype was significantly associated with a lower mortality than the other genotypes (p = 0.0363) by Cox regression analysis adjusted for age, sex, site of myocardial infarction, Killip functional class, reperfusion therapy during acute phase, ACE inhibitor use, and beta-blocker use.

CONCLUSIONS

In a selected cohort of Japanese patients, the DD genotype was associated with a significantly lower cardiac mortality after a first myocardial infarction.

TIMI frame count immediately after primary coronary angioplasty as a predictor of functional recovery in patients with TIMI 3 reperfused acute myocardial infarction

OBJECTIVES

The purpose of this study was to evaluate whether higher coronary blood flow, estimated by the corrected Thrombolysis In Myocardial Infarction (TIMI) frame count (CTFC), is related to better functional and clinical outcome after successful percutaneous transluminal coronary angioplasty (PTCA) in patients with acute myocardial infarction (AMI).

BACKGROUND

Experimental studies have found that functional recovery of the infarcted myocardium was associated with increased blood flow (reactive hyperemia) to the infarcted bed shortly after reperfusion.

METHODS

We measured CTFC immediately after successful (TIMI 3) primary PTCA in 104 consecutive patients with their first AMI. Wall motion score index (WMSI) and the presence of pericardial effusion were assessed by two-dimensional echocardiography before and one month after PTCA.

RESULTS

The patients were divided into two groups according to mean CTFC for corresponding coronary artery of the control group: TIMI 3 slow group (45 patients, 40 > CTFC > or = 23) and TIMI 3 fast group (59 patients, CTFC < 23). There were no significant differences in the baseline characteristics and WMSI before reperfusion between the two groups. Improvement of WMSI in the TIMI 3 fast group was significantly greater than that of the TIMI 3 slow group (1.33 +/- 0.52 vs. 0.60 +/- 0.34, p < 0.001). Pericardial effusion and intractable heart failure were observed more frequently in the TIMI 3 slow group than in the TIMI 3 fast group (27 vs. 10%; p < 0.05, 36 vs. 17%; p < 0.05). Corrected TIMI frame count, assessed as a continuous variable, had a significant correlation with the change in WMSI (r = 0.60, p < 0.001) after adjusting for age, gender, history of hypertension, history of diabetes, elapsed time to PTCA, collateral grade, presence of antegrade flow before PTCA and number of diseased vessels.

CONCLUSIONS

Lower CTFC of the infarct-related artery immediately after PTCA was associated with greater functional recovery; and hence, CTFC can predict clinical and functional outcome in patients with successful PTCA.

Implantation of bone marrow mononuclear cells into ischemic myocardium enhances collateral perfusion and regional function via side supply of angioblasts, angiogenic ligands, and cytokines

BACKGROUND

Bone marrow implantation (BMI) was shown to enhance angiogenesis in a rat ischemic heart model. This preclinical study using a swine model was designed to test the safety and therapeutic effectiveness of BMI.

METHODS AND RESULTS

BM-derived mononuclear cells (BM-MNCs) were injected into a zone made ischemic by coronary artery ligation. Three weeks after BMI, regional blood flow and capillary densities were significantly higher (4.6- and 2.8-fold, respectively), and cardiac function was improved. Angiography revealed that there was a marked increase (5.7-fold) in number of visible collateral vessels. Implantation of porcine coronary microvascular endothelial cells (CMECs) did not cause any significant increase in capillary densities. Labeled BM-MNCs were incorporated into approximately 31% of neocapillaries and corresponded to approximately 8.7% of macrophages but did not actively survive as myoblasts or fibroblasts. There was no bone formation by osteoblasts or malignant ventricular arrhythmia. Time-dependent changes in plasma levels for cardiac enzymes (troponin I and creatine kinase-MB) did not differ between the BMI, CMEC, and medium-alone implantation groups. BM-MNCs contained 16% of endothelial-lineage cells and expressed basic fibroblast growth factor>>vascular endothelial growth factor>angiopoietin 1 mRNAs, and their cardiac levels were significantly upregulated by BMI. Cardiac interleukin-1beta and tumor necrosis factor-alpha mRNA expression were also induced by BMI but not by CMEC implantation. BM-MNCs were actively differentiated to endothelial cells in vitro and formed network structure with human umbilical vein endothelial cells.

CONCLUSIONS

BMI may constitute a novel safety strategy for achieving optimal therapeutic angiogenesis by the natural ability of the BM cells to secrete potent angiogenic ligands and cytokines as well as to be incorporated into foci of neovascularization.

Accuracy of technetium-99m tetrofosmin myocardial perfusion imaging in the detection of spontaneous recanalization in patients with acute anterior myocardial infarction

To avoid the haemorrhagic risk of unnecessary thrombolysis in acute myocardial infarction (MI), early and precise diagnosis of spontaneous recanalization (SR) of the infarct-related artery is required. To clarify the accuracy of technetium-99m tetrofosmin myocardial single-photon emission tomography (SPET) in the detection of SR in patients with acute anterior MI, electrocardiography (ECG), echocardiography and 99mTc-tetrofosmin SPET imaging were performed in 49 patients with acute anterior MI before emergency coronary angiography. Defect score was calculated as the sum of the perfusion defects of each segment: from 3 (complete defect) to 0 (normal perfusion). Echocardiographic asynergic score (the sum of asynergic grades) and the greatest ST elevation of the 12-lead ECG on admission were also measured. SR was defined as Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow on emergency coronary angiography. Defect score in 11 patients with SR (9.2 +/- 3.7) was significantly lower than that in 38 patients without SR (18.5 +/- 5.0) (P < 0.001), whereas there were no significant differences in asynergic score and ST elevation between the two groups. From the receiver operating characteristic curves, the optimal cut-off points of defect score, asynergic score and ST elevation for the detection of SR were calculated to be 12, 13 and 3.5, respectively. The sensitivity and specificity of the scintigraphic defect score (91% and 89%) were significantly higher than those of the asynergic score (64% and 68%) and ST elevation (73% and 71%). Thus, 99mTc-tetrofosmin SPET imaging on admission is a very accurate method for the detection of SR in patients with acute anterior MI.

Determinants of ventricular arrhythmias in hemodialysis patients. Evaluation of the effect of arrhythmogenic substrate and autonomic imbalance

BACKGROUND/AIMS

In chronic hemodialysis patients, we evaluated determinants of repetitive ventricular tachyarrhythmias which included late potentials and heart rate variability.

METHODS

We compared the presence of late potentials and heart rate variability obtained by ambulatory electrocardiogram (ECG), findings of echocardiography, and laboratory data between patients with and those without ventricular arrhythmias of Lown class 4A or 4B. Ambulatory ECG was recorded for 24 h from the beginning of hemodialysis. Heart rate variability was evaluated by the standard deviation of the normal RR interval (SDNN).

RESULTS

Thirty patients (17%) had ventricular arrhythmias of Lown class 4A or 4B. They were older than patients without such arrhythmias (p=0.0021). Left-ventricular wall motion score (2.0+/-3.9 and 0.3+/-1.2, respectively, p < 0.0001) and left-ventricular mass index (167 +/-59 and 140+/-44 g/m2, respectively, p=0.0053) were larger in patients with ventricular arrhythmias of Lown class 4A or 4B than in those without. Stepwise logistic regression analysis was performed to select variables related to ventricular arrhythmias of Lown class 4A or 4B from the following 8 candidate variables; age, sex, presence of ischemic heart disease, diabetic nephropathy as the primary renal disease, presence of late potentials, SDNN, left-ventricular wall motion score and left-ventricular mass index. Higher left-ventricular wall motion score (p < 0.0001), older age (p=0.0022) and male sex (p=0.0235) were the variables associated with ventricular arrhythmias of Lown class 4A or 4B.

CONCLUSION

In patients receiving hemodialysis, predominantly with chronic glomerulonephritis, ventricular arrhythmias of Lown class 4A or 4B were not associated with arrhythmogenic substrate revealed by late potentials or autonomic dysfunction assessed by heart rate variability. Left-ventricular wall motion abnormalities, age and sex were significant factors.

Mild mitral regurgitation was associated with increased prevalence of thromboembolic events in patients with nonrheumatic atrial fibrillation

Although several studies demonstrated that the presence of significant mitral regurgitation was associated with reduced occurrence of thromboembolism, little data is available concerning the effect of mild mitral regurgitation on the occurrence of thromboembolic events. To evaluate the association between mild mitral regurgitation and thromboembolic events, we reviewed 232 patients' records between January 1996 and September 1997 who had nonrheumatic atrial fibrillation. There were 59 patients (25%) with mitral regurgitation > or = grade 2, 69 patients (30%) with grade 1 mitral regurgitation, and 104 patients (45%) with no mitral regurgitation. Patients with grade 1 mitral regurgitation had significantly higher prevalence of thromboembolic events (28%) than those with mitral regurgitation > or = grade 2 (8%, P=0.006) or those with no mitral regurgitation (11%, P=0.007). A history of previous thromboembolic events were compared between 173 patients with grade 1 mitral regurgitation and those with no mitral regurgitation using the logistic regression analysis adjusted for age, sex, administration of warfarin, and presence of hypertension, diabetes mellitus, structural heart disease, enlarged left atrium (> or = 40 mm), chronic atrial fibrillation, and grade 1 mitral regurgitation. Grade 1 mitral regurgitation (odds ratio=2.689, 95% confidence interval=1.039-7.189, P=0.0434) and no warfarin administration (odds ratio=0.045, 95% confidence interval=0.002-0.242, P=0.0036) were significantly associated with the history of thromboembolic events. The presence of mild mitral regurgitation in nonrheumatic atrial fibrillation was associated with higher prevalence of thromboembolic events.

A new amyloidogenic transthyretin variant, [D38A], detected by electrospray ionization/mass spectrometry

A new variant of transthyretin (TTR) was detected by mass spectrometry (MS) in a 63-year-old Japanese female patient suffering from amyloidosis. TTR was analyzed by 2-dimensional liquid chromatography coupled with electrospray ionization MS. Variant TTR showed extra peaks in addition to normal TTR peaks. The extra peaks were about 44 Da smaller than normal TTR peaks, and the abundance of variant peaks showed about 80% of the corresponding normal free and adduct peaks. Direct genomic DNA sequencing of TTR exon 2 showed both adenine and cytosine in the position corresponding to the second base of codon 38. This codes for a variant alanine (GCT) as well as the normal aspartic acid (GAT), indicating that the case is heterozygous for the substitution, [D38A].

Heart rate variability and left ventricular dilatation early after myocardial infarction

To assess clinically whether alterations of autonomic tone precede left ventricular dilatation, heart rate variability and early left ventricular dilatation after a first myocardial infarction were assessed. Low-frequency power (LF), high-frequency power (HF), and total power (TP) were obtained by ambulatory electrocardiogram on day 1 in 53 patients with a first acute myocardial infarction. Left ventricular end-diastolic volume determined by echocardiography was obtained on day 1 and day 14. Stepwise linear regression analysis was used to assess the associations of early left ventricular dilatation with heart rate variability adjusted for clinical variables. Higher LF and TP were significantly associated with early left ventricular dilatation after adjustment for age, sex, site of myocardial infarction, acute revasucularization, peak creatine kinase level, history of hypertension, and use of angiotensin-converting enzyme inhibitors and beta-blockers. Higher LF and TP preceded early left ventricular dilatation after myocardial infarction.

Higher heart rate variability of smokers after acute myocardial infarction

Although cigarette smoking is known to be a strong risk factor for the development of coronary artery disease, several large clinical studies have demonstrated that current smokers had a favorable prognosis compared to nonsmokers after myocardial infarction. This study sought to evaluate the effect of smoking status on heart rate variability after onset of acute myocardial infarction. We studied 52 patients (34 smokers, 18 nonsmokers) with a first myocardial infarction within 24 h of onset. We recorded 24-h ambulatory ECG to calculate very low frequency power (VLF), low frequency power (LF) and high frequency power (HF) 14 days after onset. Although smokers had a tendency to be younger than nonsmokers (mean age 57 versus 62, P = 0.0812), clinical characteristics were not statistically different between smokers and nonsmokers. After adjustment for age, left ventricular ejection fraction, history of diabetes, acute revascularization and use of beta-blockers, VLF (P = 0.0183) of smokers 14 days after onset was significantly higher than for nonsmokers. In conclusion, although smoking reduces heart rate variability in the general population, higher heart rate variability was observed in smokers than nonsmokers after acute myocardial infarction under the condition of smoking cessation.

[Aortic valvular vegetation in annuloaortic ectasia due to idiopathic cystic medial necrosis: a case report]

Annuloaortic ectasia is often accompanied by Marfan syndrome and associated with infective endocarditis usually involving the mitral valves. We treated a patient with annuloaortic ectasia due to idiopathic cystic medial necrosis who developed congestive heart failure with aortic valvular vegetation. A 56-year-old man had dyspnea on effort since the beginning of January, 1997 and was admitted to our hospital on April 6, 1997 because of orthopnea. The diagnosis was congestive heart failure due to severe aortic regurgitation with annuloaortic ectasia detected by echocardiography. Medication and rest after hospitalization relieved his symptoms but congestive heart failure deteriorated after he had a high fever. At this time, a vegetation attached to the noncoronary cusp of the aortic valve was found which had not been detected on admission. Blood culture yielded Streptococcus sanguis. The diagnosis was infective endocarditis involving the aortic valve. Surgical correction (Bentall method) improved congestive heart failure and he was discharged on August 4, 1997 without recurrence of endocarditis. Infective endocarditis involving the aortic valves is a possible cause of development or deterioration of congestive heart failure in patients with annuloaortic ectasia.

Intracerebral hemorrhage after transcatheter thrombolysis of non-occluding superior mesenteric artery thrombosis

We performed transcatheter thrombolysis on a 64-year-old man with non-occluding superior mesenteric artery (SMA) thrombosis because his severe symptoms could not be controlled with medication. An enhanced computed tomography (CT) scan revealed intramural thrombosis in the SMA. We were concerned that the narrowing of the SMA lumen might progress to complete occlusion, resulting in a high likelihood of mortality. After dissolution of the SMA thrombosis, the original symptoms almost completely disappeared. However, intracranial hemorrhage occurred 8 hr after thrombolysis, requiring surgical intervention. Transcatheter thrombolysis is thought to be a useful treatment for SMA thrombosis, especially in elderly patients with a high operative risk; however, the possibility of intracerebral hemorrhage must be taken into consideration.

Determinants of heart rate variability in chronic hemodialysis patients

To clarify determinants of heart rate variability in hemodialysis patients, we evaluated 187 patients receiving chronic hemodialysis. Ambulatory electrocardiogram was recorded for 24 hours from the beginning of hemodialysis. Standard deviation of the normal RR interval (SDNN) was used as a marker of heart rate variability. Multiple regression analysis was performed to select independent variables associated with SDNN from the following 14 variables: age, sex, body mass index before hemodialysis, presence of ischemic heart disease, diabetic nephropathy as primary renal disease, smoking, duration of hemodialysis, mean blood pressure before hemodialysis, left ventricular mass index and fraction shortening in echocardiography, use of beta blockers, use of angiotensin-converting enzyme inhibitors, hematocrit, and blood urea nitrogen. Older age (P < 0.0001), presence of diabetic nephropathy as primary renal disease (P < 0.0001), lower hematocrit (P = 0.0121), larger body mass index before hemodialysis (P = 0.0133), longer duration of hemodialysis (P = 0.0200), and smoking (P = 0.0350) were associated with reduced SDNN. In hemodialysis patients, SDNN as a marker of cardiac autonomic modulation was associated with hematocrit, body mass index, and duration of hemodialysis, in addition to previously reported variables.

Association of preceding angina with in-hospital life-threatening ventricular tachyarrhythmias and late potentials in patients with a first acute myocardial infarction

We studied 140 patients with a first acute myocardial infarction to examine the effect of preceding angina as a marker of ischemic preconditioning on clinical ventricular arrhythmias and late potentials. Preceding angina was defined as the presence of ischemic chest pain within 24 hours before onset of myocardial infarction lasting no longer than 30 minutes and seen three or more times per day or at rest. Clinical features, angiographic findings, and late potentials were compared between patients with and without preceding angina. Thirty-four (24%) patients had preceding angina. Although the incidence of life-threatening ventricular tachyarrhythmias significantly differed (p = 0.0219), other clinical findings, including presence of late potentials, were not different between the two groups. Of 14 patients with life-threatening ventricular tachyarrhythmias, five events were considered as reperfusion arrhythmias. In patients who had successful reperfusion therapy, the incidence of life-threatening ventricular tachyarrhythmias had a tendency to be lower in patients with preceding angina than in those without preceding angina (p = 0.0586). Severe angina within 24 hours of onset of acute myocardial infarction is suggested to reduce occurrence of life-threatening ventricular tachyarrhythmias mainly associated with reperfusion during hospitalization.

Assessment of left ventricular myocardial perfusion and diastolic function during acetylcholine-induced diffuse coronary vasoconstriction by Doppler echocardiography and thallium-201 scintigraphy

BACKGROUND

We investigated whether diffuse coronary vasoconstriction induced by acetylcholine caused myocardial ischemia.

METHODS

We studied 30 patients (40 coronary arteries) with spontaneous chest pain or equivocal studies on treadmill exercise testing and no significant coronary stenosis or previous myocardial infarction. During the acetylcholine provocation test, Doppler echocardiography was performed, and thallium-201 was injected intravenously for scintigraphy. We used Doppler echocardiography to measure the ratio of early-to-late peak mitral flow (E:A ratio).

RESULTS

When acetylcholine was injected, the coronary arteries showed three different responses. Diffuse coronary vasoconstriction without chest pain or ischemic changes on the ECG was induced in 18 (45%) arteries and the E:A ratio decreased from 0.83 +/- 0.13 to 0.77 +/- 0.13 (P = 0.031). In 17 vessels (control arteries), the E:A ratio did not change significantly (from 0.88 +/- 0.15 to 0.88 +/- 0.18; P = 0.95). In five arteries, focal spasm was induced and the E:A ratio decreased from 0.83 +/- 0.18 to 0.66 +/- 0.13 (P = 0.043). Transient defects on thallium-201 scintigraphy were observed in the territory of eight (80%) arteries with diffuse vasoconstriction and in one (20%) control artery (P = 0.047).

CONCLUSIONS

Diffuse coronary vasoconstriction induced by intracoronary acetylcholine can decrease the regional myocardial blood flow (as shown by thallium-201 scintigraphy) and can cause global left ventricular diastolic dysfunction (as shown by the results of Doppler echocardiography).

Local treatment of rabbit VX2 rectal carcinoma with combined hyperthermia and intratumoral CDDP injection

The efficacy of combined use of hyperthermia and intratumoral cisplatin (CDDP) injection was investigated in rabbit rectal carcinoma models produced by VX2 carcinoma injection. Local hyperthermia was administered with a 13.56 MHz radiofrequency generator at 42-43 degrees C for 30 min. CDDP (3 mg) was injected into two sites within tumours. Temperatures in the VX2 rectal carcinomas reached 42-43 degrees C within 3 min following initiation of heating and remained stable. Tumour growth was inhibited markedly in rabbit undergoing combined treatment with intratumoral CDDP and hyperthermia, when compared with rabbit treated with hyperthermia or intratumoral CDDP alone. Histological examination further revealed that combined treatment resulted in more extensive tumour necrosis, when compared with hyperthermia or CDDP alone. Therefore, combined hyperthermia and CDDP intratumoral injection may be useful for neoadjuvant preoperative treatment of advanced rectal carcinomas as well as patients with recurrent rectal carcinoma.

The factor dominating the determination of left ventricular filling varies during the first five days after acute myocardial infarction

BACKGROUND

Left ventricular diastolic dysfunction may occur after the onset of acute myocardial infarction. Left ventricular diastolic filling dynamics are related to many factors. To evaluate the influence of left ventricular filling pressure on Doppler-derived left ventricular diastolic flow profiles in patients with acute myocardial infarction, we studied serial changes in filling during the first 5 days after the onset of uncomplicated acute myocardial infarction.

METHODS

The study population consisted of 14 patients with acute myocardial infarction and 15 normal subjects: Doppler echocardiographic studies (left ventricular transmitral inflow and outflow velocity patterns) were performed on admission, and on the third and fifth days after infarction. Hemodynamic parameters were measured simultaneously using Doppler echocardiography.

RESULTS

The E wave was lower, the A wave and A:E ratio were higher, deceleration half time and isometric relaxation time were prolonged, and peak left ventricular ejection flow velocity was lower in myocardial infarction patients than in normal subjects. The E wave and pulmonary capillary wedge pressure were positively correlated on the first and the third day (r = 0.77, P < 0.001, and r = 0.67, P < 0.01, respectively), but not on the fifth day. The E wave and isometric relaxation time were negatively correlated on the fifth day (r = -0.72, P < 0.01), but not on the first and third day.

CONCLUSION

Left ventricular filling pressure (preload) was an important mechanism for maintaining left ventricular filling during the first 3 days, but the relaxation of the ventricle began to play a dominant role on the fifth day.

Left ventricular diastolic filling properties in diabetic patients during isometric exercise

Left ventricular diastolic filling properties during isometric handgrip exercise were measured by pulsed Doppler echocardiography in 33 noninsulin-dependent diabetic patients with a normal ejection fraction and 15 control subjects. Diabetic patients were subdivided into two groups according to their resting left ventricular filling pattern (A/E): 18 patients were in group DM-1 (A/E < or = 1.1) and 15 patients were in group DM-2 (A/E > 1.1). At rest, A/E ratio and A wave were higher, and deceleration half-time was longer in group DM-2 than in normal subjects and group DM-1, but there was no significant difference between normal subjects and group DM-1. The A/E ratio increased significantly in all three groups during isometric handgrip exercise. However, the change in A/E from rest to peak exercise in group DM-1 (0.29 +/- 0.20) was significantly greater than in normal subjects (0.09 +/- 0.07). These results suggest that diabetes mellitus patients with normal resting left ventricular (LV) filling pattern (group DM-1) had LV diastolic filling abnormalities with isometric handgrip exercise. Doppler echocardiography with isometric handgrip exercise is useful in identifying underlying left ventricular diastolic dysfunction in diabetic patients.

Adrenal myelolipoma discovered incidentally on abdominal CT and MR imaging

This report describes an adrenal myelolipoma occurring in a 39-year-old man first noted incidentally by computed tomography (CT). The radiographic findings of this neoplasm are briefly discussed and magnetic resonance (MR) imaging of myelolipoma is also described. Myelolipomas can be distinguished from nonfunctioning adenomas by differences in signal intensity on T2-weighted images.