Quantification of Lung Perfusion Blood Volume by Dual-Energy CT in Patients With and Without Chronic Obstructive Pulmonary Disease.

Purpose: In chronic obstructive pulmonary disease (COPD), pulmonary vascular alteration is one of the characteristic features. Recently, software has been used for the quantification of lung iodine perfusion blood volume (iPBV) using dual-energy CT, allowing objective evaluation. The purpose of this study was to evaluate the quantification of lung PBV with and without COPD. Materials and Methods: This study was approved by the Institutional Review Board. Sixty-two subjects who had undergone a respiratory function test within one month underwent dual-energy CT angiography. The subjects were divided into two groups: with (n = 14) and without (n = 48) COPD. We evaluated the quantification of lung iPBV in the early phase and late phase using Syngo softwarepost contrast. Associations between lung iPBV and respiratory function (forced expiratory volume in 1 second/forced vital capacity; FEV1/FVC) and the percentage area of emphysema (%LAA-950) were also evaluated. Results: In the early phase, lung iPBV values were 20.1 ± 5.5 and 30.6 ± 7.6 Hounsfield Unit (HU) in those with and without COPD, respectively, with a significant difference between them (p < 0.0001). In the late phase, the values were 12.3 ± 3.7 and 15.3 ± 4.6 HU, respectively, with no significant difference (p = 0.051). However, this could be noticed as a trend. In the early phase, there was a weak significant correlation between lung iPBV value and FEV1/FVC (R = 0.26, p = 0.047). There were significant and moderate negative correlations between lung iPBV value and %LAA-950 in early and late phases (R = -0.57, p = 0.0002; R = -0.45, p = 0.005, respectively). Conclusions: Quantification of lung iPBV reflects reduced pulmonary perfusion in patients with COPD. It may be useful for objective evaluation of the pulmonary blood flow in patients with COPD.

Fate of aorta and clinical outcomes in patients with chronic type B aortic dissection: over 20-year experience.

AIM: In type B double-barrel aortic dissection (AD), the fate of the affected aorta, causes of death, and very long-term clinical outcomes have not been completely elucidated. The purpose of this study was to clarify the fate of the affected aorta and long-term clinical outcomes in patients with type B AD during the chronic phase. MEHODS: One hundred and four patients were entered into this study, and regular follow-up CT studies (mean; 87.6 months) were performed. Also, clinical data including AD-related events (including aneurysm formation, rupture, ischemia, and re-dissection), AD-related deaths, and long-term survival were retrospectively reviewed. RESULTS: Forty-six of 104 patients (44.2%) had one more AD-related event during the follow-up period. The actuarial event-free rates for any AD-related events of all patients were 95±2%, 75±5%, 53±6%, and 13±7% at 1, 5, 10, and 20 years, respectively. Initial aortic diameter ≥40 mm and blood flow in the false lumen were significant risk factors for AD-related events in univariate and multivariate analysis. CONCLUSION: In type B chronic aortic dissection, the affected aortas have a high incidence of AD-related events during the follow-up period. Prophylactic surgery or endovascular treatment for patients at high risk may reduce the AD-related events.

Myocardial delayed contrast-enhanced MRI: relationships between various enhancing patterns and myocardial diseases.

The concentration of MR contrast agents is relatively high in abnormal myocardial tissue, with increased extravascular space and/or abnormal contrast wash-in and wash-out characteristics. Based on this mechanism, myocardial delayed contrast-enhanced MRI has been increasingly used to detect myocardial damage. Delayed enhancement (DE) can be seen in various components, such as fibrosis, protein infiltration or possibly myocardial disarray with disorganized myocardial fibre packing. Therefore, DE can be seen in various myocardial diseases, each of which has a characteristic DE pattern. Knowledge of the relationships among various DE patterns and myocardial diseases is useful for differential diagnosis and management.

Clinical evaluation of magnetic resonance imaging flowmetry of portal and hepatic veins in patients following hepatectomy.

BACKGROUND: Hepatic blood flow was associated with degree of hepatic damage. Measurements of blood flow using ultrasonography (US) may vary due to any observer's and patient's conditions. The utility of magnetic resonance imaging (MRI) flowmetry in portal and hepatic veins was assessed. PATIENTS AND METHODS: Using the phase-contrast method, the mean flow velocity of portal (PVF) and hepatic vein (HVF) were determined by MRI and US in 75 consecutive patients with liver diseases, including 58 patients undergoing hepatectomy. The correlations between these parameters and clinicopathological findings were examined. RESULTS: PVF and HVF measured by MRI flowmetry were 12.8+/-4.5 and 14.7+/-5.3 cm/s, respectively. There was no significant correlation of both flows between MRI and US. PVF correlated significantly with portal pressure (r = -0.722; P < 0.05). There was a negative correlation between HVF and histological activity index score (r = -0.366; P < 0.05). PVF and HVF were lower in patients with cirrhosis and higher staging score (2-4) and PVF was lower in patients with higher grading score (2-3; P < 0.05). PVF and HVF were not significantly associated with postoperative complications. CONCLUSIONS: Our results suggest that MRI flowmetry is a potentially useful tool for measurement of hepatic blood flow and recommend its use for estimation of liver cirrhosis-associated impairment.

Aortic aneurysms in patients with Takayasu's arteritis: CT evaluation.

OBJECTIVE: The objective of this study was to evaluate the incidence, development, and outcome of aortic aneurysm on CT in a group of patients with Takayasu's arteritis. MATERIALS AND METHODS: We reviewed the files of 31 patients with Takayasu's arteritis between January 1990 and March 1999. All patients were followed up for more than 6 months with CT, and the mean follow-up period was 52.9 months (median, 36.0 months). In all patients, initial CT was performed within 6 months of diagnosis of Takayasu's arteritis. The study group comprised 24 female patients and seven male patients; their ages at the first CT examination ranged from 8 to 72 years (mean, 42. 6 +/- 16.5 years). RESULTS: Seventeen aortic aneurysms were found in 14 (45.2%) of the 31 patients. Patients with severe calcification of the aorta showed significantly lower incidence of aneurysm formation than those without severe calcification of the aorta (p < 0.05). Of the 17 aneurysms, three were not present at the time of initial CT and appeared during the follow-up period. Nine of 17 aneurysms increased in size during the follow-up period. Three of the nine aneurysms rapidly increased in size and ruptured during the follow-up period. In all three of these aneurysms, aortic wall thickening was identified on CT. The remaining six aneurysms slowly increased in size but did not rupture. CONCLUSION: Aortic aneurysm associated with Takayasu's arteritis is not rare. The aorta with little calcification has a greater possibility of aneurysm formation in patients with Takayasu's arteritis. Aortic aneurysms with wall thickening can have fatal consequences.

Penetrating atherosclerotic ulcer of the aorta: imaging features and disease concept.

Penetrating atherosclerotic ulcer is an ulcerating atherosclerotic lesion that penetrates the elastic lamina and is associated with hematoma formation within the media of the aortic wall. This pathologic condition is distinct from classic aortic dissection and aortic rupture; however, care should be taken in making the diagnosis, particularly if the disease is discovered incidentally. At computed tomography (CT), penetrating atherosclerotic ulcer manifests as focal involvement with adjacent subintimal hematoma and is often associated with aortic wall thickening or enhancement. Magnetic resonance imaging is superior to conventional CT in differentiating acute intramural hematoma from atherosclerotic plaque and chronic intraluminal thrombus and allows unenhanced multiplanar imaging. Spiral CT involves shorter examination times and allows high-quality two- and three-dimensional image reconstruction. CT angiography can demonstrate complex spatial relationships, mural abnormalities, and extraluminal pathologic conditions. Transesophageal echocardiography has been reported to be highly sensitive and specific in the differentiation of aortic disease, and intravascular ultrasonography may also be useful in this setting. Although rupture or other life-threatening complications are rare, patients with penetrating atherosclerotic ulcer must be followed up, particularly during the 1st month after onset. Surgical treatment may become necessary in cases involving evidence of intramural hematoma expansion, signs of impending rupture, inability to control pain, or blood pressure changes.

Symptomatic peripheral vascular tree stenosis. Comparison of subtracted and nonsubtracted 3D contrast-enhanced MR angiography with fat suppression.

OBJECTIVE: To determine the clinical feasibility of contrast-enhanced three-dimensional (3D) MR angiography (MRA) with fat suppression spectral inversion at lipids and to compare subtracted and nonsubtracted images. MATERIAL AND METHODS: In 13 patients suspected of having lower extremity ischemia, 3D dynamic contrast-enhanced MRA of the iliac and femoral arteries was performed using the fat suppression technique. The validity of the MRA interpretations of the degree of stenoses was evaluated by comparing with conventional angiography as the gold standard. The contrast-to-noise (C/N) ratios of both subtracted and nonsubtracted maximum-intensity-projection (MIP) images were calculated. RESULTS: In the arteries with stenosis of 50% or greater, the sensitivity and specificity of the subtracted MR angiograms were 100% and 96.5%, respectively, not significantly different from the corresponding values in nonsubtracted MRAs (100% and 94.1%, respectively). The C/N ratios of the subtracted images were significantly higher than those of the nonsubtracted images (p<0.001). CONCLUSION: With this technique, fat suppression can be performed with only a slight increase in the examination time. A lower dose of contrast material can be used in MRA with fat suppression than without it. Subtracted MRA improves the ease of interpretation compared to nonsubtracted MRA.

Aortoiliac and lower extremity arteries: comparison of three-dimensional dynamic contrast-enhanced subtraction MR angiography and conventional angiography.

PURPOSE: To determine the clinical feasibility of three-dimensional dynamic contrast agent-enhanced subtraction magnetic resonance (MR) angiography in patients with symptoms of lower extremity ischemia. MATERIALS AND METHODS: Twenty-three patients suspected of having lower extremity ischemia underwent three-dimensional dynamic contrast-enhanced subtraction MR angiography of the aortoiliac arteries and arteries of the lower extremity. As the reference standard, conventional angiography was also performed. For data analysis, the arterial system was divided into 10 segments. Each segment was classified as normal, mildly stenosed, moderately stenosed, severely stenosed, or occluded. RESULTS: At conventional angiography, 83 stenosed segments (14 mildly stenosed, 16 moderately stenosed, 14 severely stenosed, and 39 occluded) were identified in a total of 423 segments. For the segments with more than mild stenosis, MR angiography was 97.1% sensitive and 99.2% specific. CONCLUSION: Three-dimensional dynamic contrast-enhanced subtraction MR angiography has high sensitivity and specificity. This technique is a noninvasive alternative to conventional angiography for screening patients suspected of having lower extremity ischemia.

Infected abdominal aortic aneurysm: early CT findings.

We describe computed tomographic (CT) findings at the early stage of infected abdominal aortic aneurysm in three patients. Periaortic mass and increased fat density were the characteristic findings of early aortic infection on CT. Similar findings caused by other diseases may be difficult to differentiate by imaging alone, but these findings should be used to trigger close follow-up for patients with suspected infected abdominal aortic aneurysm.

Fate of intramural hematoma of the aorta: CT evaluation.

PURPOSE: Our goal was to investigate the fate of intramural hematoma of the aorta. METHOD: In 32 patients with intramural hematoma of the aorta, we reviewed CT (n = 32) and MR (n = 22) findings. The diagnosis was established by CT, and regular follow-up studies were performed. RESULTS: All intramural hematomas decreased in size. Ulcer-like projections (ULPs) were identified at the initial study in 6 patients and during the follow-up period in 14 patients. The ULPs progressed to saccular aneurysm in 12 patients (mean 47.0 days), while fusiform aneurysm developed in 6 patients (mean 347.7 days) without ULP. In two patients, the affected aorta progressed to overt aortic dissection. CONCLUSION: Intramural hematoma itself usually decreases in size. However, the affected aorta can progress to aneurysm or overt aortic dissection. Development of saccular aneurysm from ULPs can be considered an early complication. In cases without ULP, fusiform aneurysm may develop as a late complication. All intramural hematomas need to be followed since it seems to be difficult to predict the exact fate of intramural hematoma from the initial imaging findings.

[Stanford type A aortic dissection with closed false lumen: analysis of prognostic factors at initial CT or MRI].

Nineteen patients with Stanford type A acute aortic dissection with closed false lumen were reviewed. In the follow-up examinations, ulcerlike projection (ULP) in the ascending aorta (AA) or aortic arch (AR) was identified in 8 of 19 patients. In 5 of these 8 patients, acute cardiac tamponade occurred and 3 of them died. In the other 11 patients, there was no mortality, and only one patient underwent elective surgery. The appearance of ULP in the AA/AR is considered an indication for urgent surgery because it is regarded as a precursor of lethal complications such as cardiac tamponade. The purpose of this study was to investigate predictors of the appearance of ULP in the AA/AR with early imagings (CT or MRI) before the appearance of ULP. The patients were divided into two groups: patients with ULP in the AA/AR (8 patients) and others (11 patients). Initial CT or MRI findings of the thoracic aorta were retrospectively statistically analyzed in each group. Three predictive factors were statistically significant for the appearance of ULP in the AA/AR (diameter of the AA > or = 5 cm, thickness of the false lumen of the AA > or = 1 cm, thickness of the false lumen of the AA > or = that of the descending aorta). Close attention should be paid, if any of these 3 factors is observed at initial CT or MRI.

Tuberculous tenosynovitis of the wrist: MRI findings in three patients.

We report recent MRI findings in patients with tuberculous tenosynovitis of the wrist. Marked synovial thickening around the flexor tendons and fluid in the tendon sheath were clearly shown on MRI. Post-contrast study was useful in distinguishing the thick tenosynovium from the surrounding structures and fluid in the tendon sheath. The well-enhanced tenosynovium was also seen in the carpal tunnel in all cases. On the basis of these findings, we could easily distinguish tenosynovitis from other soft-tissue-mass lesions, such as tumors or infected ganglia. Tuberculous tenosynovitis is often not diagnosed early, and its differentiation from soft tissue tumors may be clinically difficult. MRI, particularly post-contrast study, is useful for early diagnosis of, and planning treatment for, tuberculous tenosynovitis.

Ruptured renal artery aneurysm due to Behçet's disease.

We describe a patient with Behçet's disease who developed multiple aneurysms and retroperitoneal hemorrhage due to rupture of a renal artery aneurysm. Despite successful transcatheter arterial embolization, the patient died due to pneumonia. Our retrospective review of the case revealed that the CT scan obtained 3 months before the rupture had demonstrated dilatation of bilateral renal arteries.