A case of severe peripartum cardiomyopathy requiring left ventricular assist device implantation despite the absence of late gadolinium enhancement on cardiovascular magnetic resonance imaging.

Peripartum cardiomyopathy (PPCM) is a rare disorder in which left ventricular (LV) systolic dysfunction and symptoms of heart failure (HF) occur in the peripartum period. The time to potential recovery from severe remodeling of ventricular function is difficult to predict. Although lack of late gadolinium enhancement (LGE) in cardiovascular magnetic resonance (CMR) is reportedly associated with functional recovery of the LV in some cardiomyopathies, the impact of LGE in PPCM remains unclear. We herein report a case of a patient with PPCM who demonstrated rapidly worsened ventricular function, leading to requirement of a paracorporeal left ventricular assist device (LVAD) implantation despite absence of LGE in CMR. A 34-year-old Japanese patient, G2P2A0, expecting her third delivery following a full-term pregnancy, experienced heart failure. Severe LV dysfunction and PPCM were diagnosed. CMR showed no LGE. Although standard HF therapy and bromocriptine were given, her cardiac function failed to recover, and she eventually underwent paracorporeal LVAD implantation as a bridge to heart transplantation due to the impossibility of stopping the administration of inotropic agents. .

Thoracoscopic stapler-and-loop technique for left atrial appendage closure in nonvalvular atrial fibrillation: Mid-term outcomes in 201 patients.

BACKGROUND: Left atrial appendage (LAA) closure can be an alternative to oral anticoagulation to prevent cardiogenic thromboembolisms in patients with nonvalvular atrial fibrillation. OBJECTIVE: The purpose of this study was to retrospectively evaluate the safety, completeness, and mid-term prevention of our thoracoscopic stapler-and-loop technique for LAA closure. METHODS: Patients operated on between October 2008 and February 2017 were reviewed. Endoscopic stapler and ligation loops were used. Patients received 1 month of anticoagulation before discontinuation. Hospital death and procedure-related major complications (thromboembolism, hemorrhagic events, phrenic palsy) were the primary composite endpoint for safety, and cardiogenic thromboembolisms were the endpoint for prevention. Brain magnetic resonance imaging investigated new thromboembolic spots 1 year after surgery. RESULTS: There were 201 patients (118 men, 83 women) with a mean age of 74 years (range 68-94) years, mean CHA2DS2-VASc score (± SD) 4.1 ±1.4, and mean HAS-BLED score 2.9 ± 1.0. Mean operation time was 28 minutes. All LAAs were removed, and intraoperative transesophageal echocardiography confirmed completeness of the closure in each patient. No hospital deaths or major procedure-related complications occurred. Follow-up results for 198 patients (98%) over a mean period of 48 months (range 12-110) revealed that 2 patients developed cardiogenic thromboembolisms (0.25 event per 100 patient-years). Magnetic resonance imaging of 51 patients with a mean CHA2DS2-VASc score of 4.7 ± 1.6 revealed 1 new small spot in each of 2 patients (3.9%; 3.9 spots per 100 patient-years). CONCLUSION: Our thoracoscopic stapler-and-loop technique swiftly, safely, and completely closed LAAs in patients with nonvalvular atrial fibrillation and provided acceptable mid-term prevention without anticoagulation.

Planer orientation of the bilateral semicircular canals in dizzy patients.

OBJECTIVE: Recent development of 3-dimensional analysis of eye movement enabled to detect the eye rotation axis, which is used to determine the responsible semicircular canal(s) in dizzy patients. Therefore, the knowledge of anatomical orientation of bilateral semicircular canals is essential, as all 6 canals influence the eye movements. SUBJECTS AND METHODS: Employing the new head coordinate system suitable for MR imaging, we calculated the angles of semicircular canal planes of both ears in 11 dizzy patients who had normal caloric response in both ears. RESULTS: The angles between adjacent canal pairs were nearly perpendicular in both ears. The angle between the posterior canal planes and head sagittal plane was 51° and significantly larger the angle between the anterior canal planes and head sagittal plane, which was 35°. The angle between the horizontal canal plane and head sagittal plane was almost orthogonal. Pairs of contralateral synergistic canal planes were not parallel, forming 10° between right and left horizontal canal planes, 17° between right anterior and left posterior canal planes and 19° between the right posterior and left anterior canal planes. CONCLUSION: Our measurement of the angles of adjacent canal pairs and the angle between each semicircular canal and head sagittal plane coincided with those of previous reports obtained from CT images and skull specimens. However, the angles between contralateral synergistic canal planes were more parallel than those of previous reports.

Ruptured aneurysm with extravasation observed in four-dimensional computed tomography angiography.

We report a case of subarachnoid hemorrhage with a ruptured aneurysm in the anterior communicating artery. On multiphase dynamic contrast-enhanced four-dimensional computed tomography angiography (4D CTA), we observed active bleeding from the aneurysm that manifested over time with a corkscrew-like, spindle-like, and lobulated appearance and nebulous enhancement, characteristics reported only individually previously. The volume data for 4D CTA is easy to obtain with newly developed multidetector-row computed tomography, and 4D CTA can be used for evaluating anatomical aspects, hemodynamics, and treatment selection in cases of a ruptured cerebral aneurysm.

Unenhanced ECG-gated fast spin-echo MR digital subtraction angiography (MRDSA) using short echo-spacing three-dimensional sequence of femoral arteries: initial experience.

PURPOSE: To compare the image qualities of unenhanced electrocardiographically (ECG)-gated fast spin-echo magnetic resonance digital subtraction angiography (MRDSA) using a short echo-spacing three-dimensional (3D) sequence, known as sampling perfection with application-optimized contrasts using different flip angle evolutions (SPACE), and the conventional half-Fourier single-shot turbo spin-echo (HASTE) sequence. MATERIALS AND METHODS: Unenhanced ECG-gated MRDSA using SPACE and HASTE of the femoral arteries were prospectively acquired in 13 healthy volunteers at 1.5 Tesla (T) MRI. Sequential frontal maximum-intensity-projection images produced by subtracting each of 10 systolic images from a diastolic image were evaluated quantitatively using paired t-test and qualitatively by two blinded radiologists using the Mann-Whitney U-test. RESULTS: Quantitatively, relative contrast against the background, contour sharpness index, and slope of the sequential signal changes of the superficial femoral artery of MRDSA using SPACE were significantly better than those of HASTE (P = 0.005, P = 0.001, and P < 0.0001, respectively). Qualitatively, the overall subjective image quality and sequential appearance changes of MRDSA using SPACE were significantly better than those of HASTE (P < 0.0001 and P < 0.0001, respectively). CONCLUSION: Unenhanced ECG-gated fast spin-echo MRDSA using SPACE produces increments in signal intensity, which reflect arterial pulse wave transmission, more clearly than the conventional HASTE sequence.

Assessing renal function with a rapid, handy, point-of-care whole blood creatinine meter before using contrast materials.

PURPOSE: The aim of this prospective study was to assess the reliability of a rapid, handy, point-of-care whole blood creatinine meter (PCM) in patients who were scheduled to undergo contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI). MATERIALS AND METHODS: Among patients scheduled to undergo contrast-enhanced CT or MRI examinations, 113 patients who did not have creatinine data from the prescribed intervals before the examination day (in principle, 90 days for scheduled outpatients and 7 days for inpatients and urgent patients) were included. The estimated glomerular filtration rate (eGFR) was calculated using the creatinine values measured with the PCM and those from central laboratory measurements (LAB). The two eGFR values were compared statistically with the paired t-test, Pearson's correlation coefficient, and the Bland-Altman analysis. RESULTS: The mean eGFR measured with the PCM was slightly higher than the LAB value (81.2 ± 24.6 vs. 70.2 ± 19.7 ml/min/1.73 m(2), P < 0.0001). They were well correlated (r = 0.74, y = 0.92x + 16.9, P < 0.0001). Bland-Altman plots (mean difference was 11.0 ml/min/1.73 m(2); limits of agreement were -22.4 to +44.4 ml/min/1.73 m(2)) showed a moderate agreement with some degree of dispersion. CONCLUSION: The PCM can rapidly assess renal function using a small amount of blood almost equally to that of determined in the laboratory, which may help reduce the risk of contrast material-induced complications.

Unenhanced MR angiography: techniques and clinical applications in patients with chronic kidney disease.

Alongside the two conventional unenhanced magnetic resonance (MR) angiographic techniques, namely time-of-flight and phase-contrast MR angiography, several novel techniques have since been developed, including electrocardiograph (ECG)-gated fast spin echo (FSE), steady-state free precession (SSFP), and arterial spin labeling. These techniques are increasingly being used to avoid severe complications caused by contrast materials, such as iodinated contrast material-induced nephropathy and gadolinium-induced nephrogenic systemic fibrosis. However, image acquisition and interpretation with these techniques are more complicated than with contrast-enhanced MR angiography because of numerous types of artifacts. Appropriate use of these techniques can allow diagnosis of vascular diseases in patients with chronic kidney disease without using contrast materials. For example, time-of-flight angiography is the main technique for evaluating intracranial arteries. Phase-contrast imaging is increasingly being used for physiologic evaluation rather than morphologic evaluation. Meanwhile, ECG-gated FSE MR angiography can show peripheral arteries in more detail. SSFP MR angiography with or without arterial spin labeling can provide high-resolution images of blood vessels including renal arteries, the aorta, and coronary arteries. Black-blood imaging is also used to evaluate vessel walls and intravascular abnormalities including plaque, dissection, and thrombi. The authors review the principles of the currently available unenhanced MR angiographic techniques, along with their advantages and limitations, and describe their clinical applications. This article should help readers select the most appropriate unenhanced MR angiographic technique to assess vascular diseases in patients with chronic kidney disease. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.312105075/-/DC1.

Utility of CT perfusion with 64-row multi-detector CT for acute ischemic brain stroke.

We investigated the utility of computed tomographic (CT) perfusion (CTP) with 64-row multi-detector row CT (MDCT) to diagnose acute infarction and ischemic penumbra. We reviewed 58 clinical cases with acute ischemic stroke with CTP, compared the size of the area with long mean transit time (MTT) to that with abnormal intensity in magnetic resonance (MR) diffusion-weighted imaging (DWI) to diagnose penumbra, and compared the size of the area with reduced cerebral blood volume (CBV) in CTP to that in MR DWI to evaluate sensitivity for infarction. The total sensitivity of MTT to acute ischemic lesions was 81% (47/58). Sensitivity of MTT to segmental lesions was 100% (42/42) and for spot and focal lesions, 31% (5/16). In 13 patients, penumbra was diagnosed as lesions mismatched between MTT in CTP and MR DWI. When we regarded a lesion with decreased CBV as infarction, the sensitivity of CBV to segmental lesions was 85% (11/13), and the sensitivity to small infarction was 14% (4/28). Use of 64-row MDCT improves coverage and radiation exposure in head CTP. The combination of plain CT, CT angiography, and CTP with MDCT can demonstrate all segmental ischemic lesions and most large segmental infarctions, and their combined application is useful in considering indication and contraindication for thrombolysis. The problem of low sensitivity for small lesions remains, and MR DWI may be required to assess small infarctions when findings from combined plain CT, CT angiography, and CTP are negative in patients with suspected acute brain stroke.

Diagnosing a large slowly enhanced cerebral aneurysm using four-dimensional multiphase dynamic contrast-enhanced computed tomography angiography.

Our patient was diagnosed with acute subarachnoid hemorrhage on plain head computed tomography (CT). Multiphase dynamic contrast-enhanced CT angiography on a 64-row multidetector scanner revealed a large aneurysm in the left middle cerebral artery that was not detected on conventional helical CT angiography. We believed that increased intracranial pressure and rough thrombus within the aneurysm delayed its peak enhancement. Our case demonstrates the diagnostic utility of four-dimensional CT with multiphase volume data in cases of lesions with delayed enhancement.

Accurate measurement of pulsatile flow velocity in a small tube phantom: comparison of phase-contrast cine magnetic resonance imaging and intraluminal Doppler guidewire.

PURPOSE: We compared the accuracy of magnetic resonance imaging (MRI) measurements of pulsatile flow velocity in a small tube phantom using different spatial factors versus those obtained by intraluminal Doppler guidewire examination (as reference). MATERIALS AND METHODS: We generated pulsatile flow velocities averaging about 20-290 cm/sec in a tube of 4 mm diameter; we performed phase-contrast cine MRI on pixels measuring 1.00(2)-2.50(2) mm(2). We quantified spatial peak flow velocities of a single pixel and a cluster of five pixels and spatial mean velocities within regions of interest enclosing the entire lumen in the phantom's cross-section. Finally, we compared the measurements of temporally mean and maximum flow velocity with the Doppler measurements. RESULTS: Linear correlation was excellent between both measurements of spatial peak flow velocities in one pixel. The highest spatial resolution using spatial peak flow velocities of a single pixel allowed the most accurate MRI measurements of both temporally mean and maximum pulsatile flow velocity (r = 0.97 and 0.99, respectively: MRI measurement = 0.95x + 8.9 and 0.88x + 24.0 cm/s, respectively). Otherwise, MRI measurements were significantly underestimated at lower spatial resolutions. CONCLUSION: High spatial resolution allowed accurate MRI measurement of temporally mean and maximum pulsatile flow velocity at spatial peak velocities of one pixel.

Identification of efferent flow in the superior vena cava and azygos vein confluence using cine phase-contrast MRI: speculation of the role of the azygos arch valves.

PURPOSE: We aimed to evaluate flow patterns in the superior vena cava (SVC) and azygos vein confluence with cine phase-contrast magnetic resonance imaging with consideration for the role played by the azygos arch valves. MATERIALS AND METHODS: Two-dimensional cine phase-contrast magnetic resonance images of the SVC and azygos vein confluence were prospectively acquired in 10 healthy volunteers. Flow directions during the cardiac cycle were evaluated quantitatively using sequential flow profile graphs obtained from each orthogonal image and affirmed visually by two radiologists from the oblique sagittal cine images. RESULTS: Although the blood in the SVC and azygos vein confluence had an afferent flow during the systolic phase, a slight temporal efferent flow during the diastolic phase was quantitatively observed in all cases. Flow in the SVC can also be confirmed visually. The average velocity, average maximum afferent velocity during the systolic phase and average maximum efferent velocity during the diastolic phase of the SVC were 8.7 ± 2.4, 19.9 ± 3.7 and -1.0 ± 3.2 cm/s, respectively; for the azygos vein confluence, these values were 2.2 ± 1.5, 7.1 ± 2.6 and -1.5 ± 1.1 cm/s, respectively. CONCLUSION: We verified that a slight temporal efferent flow exists in the SVC and azygos vein confluence during the diastolic phase, which suggests that the usual role of the azygos arch valves is to prevent this physiological retrograde flow.

Dual-energy subtraction imaging for diagnosing vocal cord paralysis with flat panel detector radiography.

OBJECTIVE: To investigate the clinical feasibility of dual energy subtraction (DES) imaging to improve the delineation of the vocal cord and diagnostic accuracy of vocal cord paralysis as compared with the anterior-posterior view of flat panel detector (FPD) neck radiography. MATERIALS AND METHODS: For 122 consecutive patients who underwent both a flexible laryngoscopy and conventional/DES FPD radiography, three blinded readers retrospectively graded the radiographs during phonation and inspiration on a scale of 1 (poor) to 5 (excellent) for the delineation of the vocal cord, and in consensus, reviewed the diagnostic accuracy of vocal cord paralysis employing the laryngoscopy as the reference. We compared vocal cord delineation scores and accuracy of vocal cord paralysis diagnosis by both conventional and DES techniques using kappa statistics and assessing the area under the receiver operating characteristic curve (AUC). RESULTS: Vocal cord delineation scores by DES (mean, 4.2 +/- 0.4) were significantly higher than those by conventional imaging (mean, 3.3 +/- 0.5) (p < 0.0001). Sensitivity for diagnosing vocal cord paralysis by the conventional technique was 25%, whereas the specificity was 94%. Sensitivity by DES was 75%, whereas the specificity was 96%. The diagnostic accuracy by DES was significantly superior (kappa = 0.60, AUC = 0.909) to that by conventional technique (kappa = 0.18, AUC = 0.852) (p = 0.038). CONCLUSION: Dual energy subtraction is a superior method compared to the conventional FPD radiography for delineating the vocal cord and accurately diagnosing vocal cord paralysis.

Prospective comparative study of negative oral contrast agents for magnetic resonance cholangiopancreatography.

PURPOSE: The aim of this study was to compare prospectively the image quality of magnetic resonance cholangiopancreatography (MRCP) using manganese chloride tetrahydrate (Bothdel Oral Solution 10) (MCT), a new negative oral contrast agent; ferric ammonium citrate (FerriSeltz powder 20%) (FAC); and no agent. MATERIALS AND METHODS: MRCP images (TE 970 ms) of patients administered MCT (n = 19) or FAC (n = 20) at random, and 18 patients without an agent were evaluated. The subjective image quality of the overall, extrahepatic bile duct, and pancreatic duct and the degree of elimination of gastrointestinal fluid scored by two radiologists blinded to information regarding the agent were compared using Mann-Whitney's U-test. RESULTS: The degrees of elimination of gastroduodenal fluid of MCT and FAC were significantly better than those without an agent (P < 0.01 and P < 0.01). The subjective image quality of MCT of the overall and extrahepatic bile duct were significantly better, although no significant differences for FAC were observed compared with those without an agent (P < 0.01 and P = 0.21, P = 0.02 and P = 0.16). There were no significant differences for the pancreatic duct (P = 0.12 and P = 0.19), nor were there any significant differences in the evaluations between MCT and FAC (P = 0.19-0.98). CONCLUSION: MCT has shown performance comparable to that of conventional FAC in terms of pancreatic and biliary depiction and safety.

Prospective electrocardiogram-gated axial 64-detector computed tomographic angiography vs retrospective gated helical technique to assess coronary artery bypass graft anastomosis: comparison of image quality and patient radiation dose.

BACKGROUND: In the present study the effective dose and image quality at distal anastomoses were retrospectively compared between prospective electrocardiogram (ECG)-gated axial and retrospective ECG-gated helical techniques on 64-detector computed tomographic (CT) angiography following coronary artery bypass graft surgery. METHODS AND RESULTS: Following bypass surgery, 52 patients with a heart rate <65 beats/min underwent CT angiography: 26 patients each with prospective and retrospective ECG gating techniques. The effective dose was compared between the 2 groups using a 4-point scale (4, excellent; 1, poor) to grade the quality of curved multiplanar reformation images at distal anastomoses. Patient characteristics of the 2 groups were well matched, and the same CT scan parameters were used for both, except for the interval between surgery and CT examination, tube current, and image noise index. Image quality scores did not differ significantly (3.26+/-0.95 vs 3.35+/-0.87; P=0.63), but the effective dose was significantly lower in the prospective (7.3+/-1.8 mSv) than in the retrospective gating group (23.6+/-4.5 mSv) (P<0.0001). CONCLUSIONS: Following bypass surgery, 64-detector CT angiography using prospective ECG gating is superior to retrospective gating in limiting the radiation dose and maintaining the image quality of distal anastomoses.

Hyperattenuating signs at unenhanced CT indicating acute vascular disease.

When a vascular disease is suspected, the focus is usually on morphologic features seen at contrast material-enhanced multidetector computed tomography (CT). However, unenhanced CT also plays an important role in revealing so-called hyperattenuating signs, which represent a slight increase in the focal attenuation of a vessel. Hyperattenuating signs are occasionally observed when an acute clot has formed in a vessel and can be seen in various vascular diseases, including acute arterial occlusion, acute arterial dissection, aneurysm rupture, and acute venous thrombosis. The attenuation of these signs tends to increase because the concentration of hemoglobin increases as water content decreases. Hyperattenuating signs are a transient phenomenon, as the attenuation gradually decreases. Therefore, they can serve as unique findings indicating an acute state. Although hyperattenuating signs are not well understood, recognition of these signs is important because they can help reveal serious acute vascular diseases even at unenhanced CT.

A new coordinates system for cranial organs using magnetic resonance imaging.

CONCLUSION: We developed a new coordinates system for magnetic resonance imaging (MRI) that utilizes the labyrinth and eyeballs as references to measure the spatial arrangement of cranial organs, and we verified its usefulness by observing small structures in the labyrinth in 39 ears from 33 patients. Our new coordinates system could be used for stereotactic analysis of cranial organs in MRI. OBJECTIVES: To research semicircular canal anatomy in healthy organisms, we propose a method that employs references visible on MRI for stereotactic measurement of cranial structures, and we evaluated the usefulness of our method. METHODS: Using the new coordinates system and vector analysis, we calculated angles among the semicircular canals and sagittal head plane from MRI volume data containing temporal bone and orbit. RESULTS: The angle between the anterior semicircular canal plane and sagittal plane was 35.3 +/- 4.1 degrees; posterior semicircular canal plane and sagittal plane, 50.9 +/- 4.7 degrees; and horizontal semicircular canal plane and sagittal plane, 90.4 +/- 7.0 degrees. The angle between the anterior and posterior semicircular canal planes was 95.1 +/- 4.2 degrees; anterior and horizontal semicircular canal planes, 92.3 +/- 7.5 degrees; and posterior and horizontal semicircular canal planes, 93.5 +/- 4.9 degrees.

Defining juxtapapillary diverticulum with 3D segmented trueFISP MRCP: comparison with conventional MRCP sequences with an oral negative contrast agent.

PURPOSE: To compare three-dimensional segmented true fast imaging with steady-state precession magnetic resonance cholangiopancreatography (3D-trueFISP-MRCP) to conventional MRCP sequences with an oral negative contrast agent for diagnosing juxtapapillary diverticulum. MATERIALS AND METHODS: A total of 42 patients with (n = 21) and without (n = 21) juxtapapillary diverticulum confirmed by endoscopic retrograde cholangiopancreatography (ERCP) were evaluated. Three MRCP sequences, 3D-trueFISP-MRCP, two-dimensional rapid acquisition with relaxation enhancement MRCP (2D-RARE-MRCP), and 3D T(2)-weighted turbo spin-echo MRCP (3D-TSE-MRCP), obtained after administering an oral negative contrast agent (FerriSeltz; Otsuka Pharmaceutical, Tokushima, Japan) were compared. Two radiologists independently and blindly interpreted the presence or absence of juxtapapillary diverticulum and its positional relationship against the papilla. The detectability of juxtapapillary diverticulum of each sequence as decided by consensus was then compared. Kappa statistics were used to measure interobserver agreement of the classifications. RESULTS: The sensitivity, specificity, and accuracy for detecting juxtapapillary diverticulum of 3D-trueFISPMRCP (61.9%, 85.7%, and 73.8%) were substantively higher than those of 2D-RARE-MRCP (0.0%, 100%, and 50.0%) and 3D-TSE-MRCP (9.5%, 100%, and 54.8%). Interobserver agreement of the position of juxtapapillary diverticulum by 3D-trueFISP-MRCP was good (kappa = 0.55). CONCLUSION: 3D-trueFISP-MRCP can define juxtapapillary diverticulum even with an oral negative contrast agent, whereas conventional MRCP sequences cannot.

Comparison of SPACE and 3D TSE MRCP at 1.5T focusing on difference in echo spacing.

PURPOSE: We compared the image quality of SPACE (sampling perfection with application optimized contrasts using different flip angle evolutions) and conventional 3D turbo spin echo (TSE) magnetic resonance cholangiopancreatography (MRCP) at 1.5 tesla with regard to difference in echo spacing. METHODS: Twenty healthy volunteers prospectively underwent navigator-triggered SPACE and 3D TSE MRCP at 1.5T with identical parameters, except for echo spacing. Quantitative analyses of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), relative contrast, and contour sharpness index of each segment of the pancreaticobiliary tree were compared using paired t-tests. Qualitative analyses on a 5-point scale (1, excellent; 5, poor) scored by 2 independent radiologists were compared using Wilcoxon signed-rank test. RESULTS: The SNR, CNR, and contour sharpness index of each segment were significantly better for the SPACE sequence than 3D TSE (P < 0.05). Relative contrast and subjective image quality were not significantly different (P > 0.05). CONCLUSION: We verified SPACE MRCP quantitatively superior to conventional 3D TSE MRCP at 1.5T as a result of shortening of echo spacing.

Flow direction of ascending lumbar veins on magnetic resonance angiography and venography: would "descending lumbar veins" be a more precise name physiologically?

BACKGROUND: Physiological flow direction of ascending lumbar vein (ALV) is not well recognized. METHODS: Two-dimensional time-of-flight magnetic resonance angiography (MRA) examinations of the lower extremities in 44 patients and venography (MRV) in 59 patients were retrospectively reviewed. chi2 analysis was used to compare the frequency of ALV detection between the MRA and MRV groups and between cases with filling defects above the ALV confluence and other cases in the MRV group. RESULTS: Frequency of ALV detection was significantly higher in the MRA group (60 of 88 veins, 68.2%) than in the MRV group (9 of 118 veins, 7.6%, P < 0.0001) and in cases with filling defects above the ALV confluence (8 of 23 veins, 34.8%; 6 were compression of the left common iliac vein by the right common iliac artery, 2 were thrombus of the proximal bilateral common iliac veins) than in other cases (1 of 95 veins, 1.1%) in the MRV group (P < 0.0001). CONCLUSIONS: Without compression or occlusion above the ALV confluence, the general flow direction of the ALVs is not ascending but descending, suggesting that "descending lumbar veins" is a more physiologically precise name for these veins than ALVs.