Presurgical assessment of flow variability in an azygos vein aneurysm using 4D-flow MRI.

Azygos vein aneurysm (AVA) is necessary to prevent pulmonary embolism due to the outflow of a thrombus or rupture of the aneurysm. However, there is no established modality to assess the properties of AVA. Time-resolved three-dimensional phase-contrast magnetic resonance imaging (4D-flow MRI) has been used to examine the hemodynamics in various fields. We report a case of AVA to evaluate the flow variability and adhesions of surrounding tissues using 4D-flow MRI. The findings of the study suggested aneurysm turbulence and the absence of thrombi. The cine image, which showed a sliding wall synchronized to the heartbeat, indicated no adhesion to the superior vena cava. Based on these results, the thoracoscopic approach was deemed possible preoperatively. Thoracoscopic AVA resection was performed, and the postoperative course was uneventful. This study documented the utility of 4D-flow MRI for a detailed evaluation of AVA.

Portal hypertension in patients with cirrhosis: indirect assessment of hepatic venous pressure gradient by measuring azygos flow with 2D-cine phase-contrast magnetic resonance imaging.

OBJECTIVES: To measure azygos, portal and aortic flow by two-dimensional cine phase-contrast magnetic resonance imaging (2D-cine PC MRI), and to compare the MRI values to hepatic venous pressure gradient (HVPG) measurements, in patients with cirrhosis. METHODS: Sixty-nine patients with cirrhosis were prospectively included. All patients underwent HVPG measurements, upper gastrointestinal endoscopy and 2D-cine PC MRI measurements of azygos, portal and aortic blood flow. Univariate and multivariate regression analyses were used to evaluate the correlation between the blood flow and HVPG. The performance of 2D-cine PC MRI to diagnose severe portal hypertension (HVPG ≥ 16 mmHg) was determined by receiver operating characteristic curve (ROC) analysis, and area under the curves (AUC) were compared. RESULTS: Azygos and aortic flow values were associated with HVPG in univariate linear regression model. Azygos flow (p < 10(-3)), aortic flow (p = 0.001), age (p = 0.001) and presence of varices (p < 10(-3)) were independently associated with HVPG. Azygos flow (AUC = 0.96 (95 % CI [0.91-1.00]) had significantly higher AUC than aortic (AUC = 0.64 (95 % CI [0.51-0.77]) or portal blood flow (AUC = 0.40 (95 % CI [0.25-0.54]). CONCLUSIONS: 2D-cine PC MRI is a promising technique to evaluate significant portal hypertension in patients with cirrhosis. KEY POINTS: • Noninvasive HVPG assessment can be performed with MRI azygos flow. • Azygos MRI flow is an easy-to-measure marker to detect significant portal hypertension. • MRI flow is more specific that varice grade to detect portal hypertension.

Endovascular diagnosis and management of chronic cerebrospinal venous insufficiency: retrospective analysis of 30-day morbidity and mortality in 95 consecutive patients.

OBJECTIVE: The purpose of this study is to report the 30-day morbidity and mortality associated with the endovascular diagnosis and management of chronic cerebrospinal venous insufficiency. MATERIALS AND METHODS: The medical records of 95 consecutive patients (60 women and 35 men) with a mean age of 48 years (age range, 25-66 years) who underwent diagnostic endovascular evaluation and intervention for chronic cerebrospinal venous insufficiency between June 2010 and September 2011 were reviewed retrospectively. All patients had a diagnosis of multiple sclerosis by McDonald criteria. Endovascular evaluation of the internal jugular and azygos veins was performed with digital subtraction venography and intravascular ultrasound. Indications for percutaneous transluminal angioplasty (PTA) were venographic findings of a greater than 50% diameter stenosis, the presence of reflux on digital subtraction venography, greater than 50% cross-sectional area stenosis by intravascular ultra-sound, or a finding of abnormal thick valves or webs by either method. The primary endpoint of this study was the 30-day mortality, and the secondary endpoint was the presence of major complications. Results are presented as means and percentages. RESULTS: A total of 107 procedures were performed in 95 patients. Endovascular evaluation showed venous lesions requiring intervention in 90 of 95 patients (94.7%) and was negative in five of 95 patients (5.3%). A total of 193 venous lesions were treated; angioplasty was technically successful in 188 of 193 (97.4%) lesions. Internal jugular vein thrombosis after PTA was identified in three of 95 (3.2%) of the treated patients. Bleeding at the puncture site not requiring transfusion occurred in four of 95 patients (4.2%). There were no reported procedure-related deaths. CONCLUSION: The results of the current study suggest that endovascular evaluation and management of chronic cerebrospinal venous insufficiency is safe, with low morbidity and no procedure-related mortality.

Catheter venography for the assessment of internal jugular veins and azygous vein: position statement by expert panel of the International Society for Neurovascular Disease.

This document by an expert panel of the International Society for Neurovascular Disease is aimed at presenting current technique and interpretation of catheter venography of the internal jugular veins, azygous vein and other veins draining the central nervous system. Although interventionalists agree on general rules, significant differences exist in terms of details of venographic technique and interpretations of angiographic pictures. It is also suggested that debatable findings should be investigated using multimodal diagnostics. Finally, the authors recommend that any publication on chronic cerebrospinal venous insufficiency should include detailed description of venographic technique used, to facilitate a comparison of published results in this area.

Collateral flow measurement by phase-contrast magnetic resonance imaging for the assessment of systemic venous baffle patency after atrial switch repair for transposition of the great arteries.

PURPOSE: We aimed to describe and compare azygos vein flow patterns of patients with obstructed and unobstructed systemic venous baffle after atrial switch repair for d-transposition of the great arteries (TGA). We hypothesized that phase-contrast magnetic resonance imaging would enable characterization of retrograde collateral flow across the azygos vein in cases of systemic venous baffle obstruction. MATERIALS AND METHODS: This is a retrospective, cross-sectional study. Twelve patients with atrial switch repair for TGA were examined. Azygos flow index was measured with phase-contrast magnetic resonance imaging; comparison was made between patients with documented systemic venous baffle obstruction (n=3) and a control group of patients without baffle obstruction (n=9). RESULTS: Patients with systemic venous baffle obstruction had a distinctive azygos flow pattern that was retrograde and an increased amount of azygos flow compared with patients without obstruction [median (range), -436 (-455/-399) vs. 103 (51/125) mL/min/m2; P=0.01]. CONCLUSIONS: Patients with systemic venous baffle obstruction have a characteristic collateral flow across the azygos vein. Azygos vein flow measurement may be used for the assessment of baffle patency in patients after atrial switch repair for TGA. However, diagnostic accuracy needs to be tested in a larger population.

Comparison of breath-hold 2D phase-contrast with non breath-hold cine phase-contrast MRA in the assessment of azygos venous blood flow in portal hypertension.

Azygos venous blood flow as an index of blood flow through the gastroesophageal collaterals and varices is of value in the prediction of gastrointestinal bleeding. Measurement of azygos venous blood flow has been achieved by non breath-hold (NBH) cine phase-contrast magnetic resonance imaging. The objective of this study was to compare the faster breath-hold (BH) phase-contrast technique with the standard (NBH) cine phase-contrast technique in the measurement of azygos blood flow. Thirty-two cirrhotic patients with esophageal varices were examined by magnetic resonance imaging using a BH technique and a NBH cine phase-contrast technique to measure the flow velocity, flow volume and calibre of the azygos vein at the mid-right atrial level. The flow values were obtained on the velocity image of the phase-contrast study. Values obtained from the two methods were evaluated statistically for the strength and significance of correlation by the Pearson test. Measurement by the BH method performed at full-inspiration as well as end-expiration was also obtained in 15 healthy volunteers. The breath-hold phase-contrast method has significant but weak correlation with non BH cine phase-contrast method in the measurement of azygos venous blood flow volume (r = 0.55, p < 0.01) and flow velocity (r = 0.43, p = 0.01). However, the calibre of the azygos vein gave a strong correlation in these two methods (0.82). In the subgroup of patients whose azygos blood flow velocity was greater than 7.4 cm/s, the correlation of azygos blood flow volume is strong (r = 0.80, p < 0.01). The azygos vein calibre remains highly correlated between the BH and NBH method, in both high flow velocity (r = 0.73) and low flow velocity (r = 0.83) groups. Breath-hold sequence leads to higher values for flow velocity and flow volume in the cirrhotic patients and also the control group. In patients with portal hypertension, BH 2D phase-contrast (PC) magnetic resonance angiography (MRA) could give a comparable estimation of the calibre of the azygos vein as the NBH 2D cine PC MRA but not for azygos flow volume. In patients with high azygos flow velocity, the strong correlation in flow volume between the BH and NBH method suggests that the BH method may be a time-saving alternative to the NBH method.

Interruption of the inferior vena cava with azygos/hemiazygos continuation accompanied by distinct renal vein anomalies: MRA and CT assessment.

We report a case of interruption of the inferior vena cava with azygos/hemiazygos continuation and additional variations of the renal veins, an uncommon developmental anomaly. Magnetic resonance angiography and computed tomography, in association with clinical awareness, can be used to diagnose this entity.

Endoscopic Doppler ultrasound for measurement of azygos blood flow. Validation against thermodilution and assessment of pharmacological effects of terlipressin in portal hypertension.

BACKGROUND: Endoscopic ultrasound (EUS) is a new modality allowing real-time flow measurements by means of the Doppler technique. The aim of the study was to evaluate azygos blood flow measurements by endoscopic ultrasound. METHODS: Measurements of azygos blood flow by EUS and by the thermodilution technique were compared in 20 patients with portal hypertension. The ability of EUS flowmetry to detect changes in the azygos and portal venous flow after an intravenous dose of 2 mg of terlipressin was evaluated in 13 of the patients in a double-blind, randomized, placebo-controlled, cross-over design. RESULTS: The EUS Doppler and thermodilution measurements correlated significantly (R=0.81, P < 0.001). The azygos blood flow was found to be 14% higher by the EUS method than by thermodilution. The coefficient of variation of the EUS Doppler measurements of the azygos blood flow was 14.8%. After administration of terlipressin, the azygos blood flow, as measured by EUS Doppler, decreased significantly by 23% from 915 to 704 ml/min (P = 0.014) and the portal venous flow decreased by 28% from 1170 to 789 ml/min (P = 0.03). No effects of placebo were detected. CONCLUSIONS: These results show that EUS measurement of the azygos blood flow correlate strongly to the measurements by the thermodilution technique, and EUS is moreover well tolerated by the patients. The method is applicable for monitoring pharmacological effects on the superior porto-systemic collateral circulation and portal venous flow in patients with portal hypertension.

Influence of a mixed meal on splanchnic and interscapular energy expenditure in humans.

Pulmonary, splanchnic, and interscapular O2 uptake was studied in 14 male volunteers before and for 90 min after a mixed meal. Thermistor catheters were inserted into a hepatic vein, the azygous vein, the pulmonary artery, and the aorta. Systemic and regional blood flows were determined during indirect calorimetry measurements and recordings of blood temperature. After the meal, pulmonary O2 uptake rose by 33-49 ml/min and splanchnic O2 uptake increased by 16-25 ml/min. In the azygous region O2 uptake did not increase significantly. Cardiac output increased after the meal by 1.1-1.5 l/min and splanchnic blood flow rose by 0.4-0.9 l/min. Azygous venous blood flow increased from 130 +/- 19 ml/min to 163 +/- 23 ml/min. In relation to splanchnic O2 uptake, the blood-drained splanchnic heat was low, 11 +/- 1 J/ml, and decreased to 7 +/- 1 J/ml after the meal. We conclude that after a mixed meal approximately one-half of the rise in O2 uptake occurs in the splanchnic organs; azygous-drained tissues, including possible interscapular brown adipose tissue, contribute minimally. The amount of heat drained with blood from the splanchnic region was low in relation to the splanchnic O2 uptake, indicating that splanchnic heat may be dissipated by routes other than the perfusing blood.

Assessment of portal hypertension by endoscopic ultrasonography.

Endoscopic ultrasonography (EUS) was performed in 40 patients with portal hypertension (PH) and in 48 control subjects. The azygous, splenic, mesenteric, and portal veins were displayed in both groups. However, esophageal and gastric varices, periesophageal and perigastric collateral veins, and submucosal gastric venules were displayed only in patients with portal hypertension. EUS was inferior to endoscopy in detecting and grading esophageal varices (p less than 0.0005), but EUS was superior in the detection of varices in the fundus of the stomach (p less than 0.0005). Detection of periesophageal veins by EUS increased with increasing diameter of esophageal varices at endoscopy (57% in grade 1, 89% in grade 2, and 100% in grade 3), and there was a direct correlation between endoscopic grade and the diameter of the periesophageal collateral veins at EUS. The diameter of the azygous vein by EUS at its distal and proximal margins was significantly greater in patients with PH (p less than 0.001); the EUS diameter of the azygous vein was significantly larger with variceal grade 2 compared with grade 1 (p less than 0.02 and p less than 0.01, respectively). In portal hypertensive gastropathy, endoscopic and EUS detection were coincident. No correlation was found between the presence of portal hypertensive gastropathy, endoscopic grade of esophageal varices, and detection of gastric varices at EUS.

Preoperative assessment of resectability for carcinoma of the thoracic esophagus. Part I. Esophagogram and azygogram.

The length and radiologic type of tumor, esophageal axis and azygogram were examined in 208 patients with carcinoma of the thoracic esophagus who underwent esophageal resection from 1965 to 1975. An histologic examination was performed on all resected specimens. These examinations were used as diagnostic aids to determine the resectability of esophageal carcinoma before surgery. Tumor length did not seem an adequate parameter on deciding resectability; nor did the radiologic type of tumor. Examination of the esophageal axis was in determining resectability. The azygogram gave the most accurate information about resectability of these 4 parameters. The probability of a correct diagnosis regarding differentiation of noncurative a3 lesions from other resectable lesions was 85.6%.