Comparison of Duplex sonography and color Doppler imaging in renal allograft evaluation: a prospective study

A prospective study compared the diagnostic capability of quantitative Duplex sonography (DS) and color Doppler imaging (CDI) in 49 consecutive patients with 50 renal allografts. Sixty five DS examinations and 65 CDI examinations were performed by two independent investigators on two different machines on the same day. The resistive index (RI) was calculated and the color flow of renal arteries was observed up to the arcuate arteries. There was good correlation of RI values obtained by DS and CDI at all vascular sites. Thirty one allografts were functioning stably and 19 were in a state of dysfunction, defined by histology (n = 17). Forty allografts presented with a RI < 0.9 and normal color flow. All five allografts with a pathologic RI 0.9 showed abnormal color flow (missing flow in arcuate and/or interlobar arteries). Five allografts had a RI < 0.9 but abnormal color flow, possibly due to atrial fibrillation, hypertension, heart failure or a combination of these. A normal color flow pattern excludes severe vascular compromise to the allograft. In addition, CDI revealed three biopsy-related vascular lesions; two of them had been missed by DS.     

The use of deep inspiration preceding the valsalva maneuver and rapid expiration in color doppler imaging of the lower extremity veins

Deep inspiration preceding Valsalva maneuver and rapid expiration immediately following it (DIVE) enhance venous blood flow on color Doppler flow imaging (CDI). The effect of DIVE was assessed in 115 consecutive lower extremity examinations. Of these, 95 or 115 (83%) had negative CDI sonograms, and 20 of 115 (17%) had partially (six of 115) or completely (14 of 115) occluding deep vein thrombosis. DIVE enhanced venous blood flow in 68% of the negative cases, resulting in transient venous distention, and/or more complete color filling, and/or greater spectral flow velocities. The 14 cases with completely occluding thrombi showed no response to DIVE. Six cases with partially occluding thrombi showed moderate to mild response to DIVE, with improved color delineation of the residual patent lumen around the thrombus. The authors conclude that DIVE facilitates deep venous CDI, especially when compression cannot be used to augment venous flow.     

Colour doppler imaging of partial subclavian steal syndrome

The case of a 67-year-old woman with symptoms related to the vertebro-basilar system and blood pressure difference of the upper extremities is presented. Colour-Doppler imaging (CDI) with additional spectral tracing revealed partial subclavian steal syndrome with retrograde flow in the left vertebral artery during systole, which could be significantly enhanced by reactive hyperemia after of arm exercise. Angiography confirmed a highgrade stenosis of the proximal subclavian artery and balloon angioplasty was performed. Nonivasive follow-up by CDI demonstrated regular antegrade vertebral artery flow at rest, but minimal retrograde systolic flow after left arm exercise.     

Color Doppler US imaging during pediatric neurosurgical and neuroradiologic procedures

Experience with color Doppler imaging (CDI) during 16 pediatric intraoperative and one percutaneous neuro-radiologic procedures was reviewed to assess whether CDI increased the success rate or decreased the procedure time, thus contributing substantially to procedure performance. Intraoperative CDI was used to rapidly identify abnormal vessels or displacement of normal vessels and correlated with preoperative studies. In six cases (four vascular malformations, one mycotic aneurysm, and one hamartoma), surgical resection was altered on the basis of flow information obtained. In one case of percutaneous embolization of a Galenic malformation, CDI provided information contributing to the cessation of the procedure. In six cases (debulking of three gliomas, resection of one vascular malformation, and two biopsies of nonneoplastic conditions), information was added but did not alter the surgical approach. In the remaining four cases (three cerebrospinal fluid drainage procedures, one posterior fossa decompression), no additional information was obtained. Consultation among the ultrasound staff, neuroradiologists, and neurosurgeons before the operative procedure maximized the usefulness of CDI, thus aiding in the success of surgery.     

Measurement of tendon excursion velocity with colour Doppler imaging: a preliminary study on flexor pollicis longus muscle

Purpose: To study the use of colour Doppler imaging (CDI) for the measurement of maximum and mean tendon velocity. Recent studies showed that CDI, normally used for blood flow examinations, can be used for the imaging of tendons at the hand and wrist region. Although other modalities are available for imaging of the musculo-skeletal system, in vivo measurements of the velocity of tendon excursion are not possible. Methods: The flexor pollicis longus (FPL) tendon of 16 healthy volunteers was measured bilaterally at two levels (wrist and thenar). A splint from the fingers along the proximal lower arm was applied. The thumb was fixed to the splint from the first phalanx to allow flexion of the interphalangeal (IP) joint only. Pulsed CDI was used for the measurements. The maximum and mean velocities of the FPL tendon were measured at spectrum display mode during continuous voluntary contractions. At least 10 sequential Doppler peaks (cm/s) were recorded at every trial. The measurements were repeated three times. Paired t-test and correlation coefficients were calculated between levels on the same side and the opposite side. Results: No significant differences were found between two levels of the same hand and of the opposite hand. As expected, the data revealed variations in the inter-individual tendon velocities. Conclusions: The velocity of the excursion of the FPL tendon can be measured with CDI with good reproducibility. It is expected that velocity measurements can be used in the future for the assessment of other tendons affected by various disorders.     

Color Doppler imaging of intracranial vessels in the neonate

This study was performed to examine the effectiveness of color Doppler imaging (CDI) in demonstrating the neonatal intracranial vessels and altered intracranial flow patterns and to determine the optimal approach in imaging and intracranial vasculature. The study was conducted in two parts. First, 14 neonates were examined with CDI by using a standard approach through the anterior fontanel. Whenever possible, views through the posterior fontanel and the temporal bone were obtained also. The anterior cerebral, M1 segment of the middle cerebral, distal internal carotid, and basilar arteries were demonstrated consistently. Portions of the vertebral distal middle cerebral, and posterior cerebral arteries were frequently visualized. In the second part of the study, we examined 10 neonates who had undergone extracorporeal membrane oxygenation. In this group of patients, CDI was able to demonstrate occlusion of the right internal carotid artery and the reversal of flow through the ipsilateral A1 segment. Increased flow on the contralateral side and in the basilar artery was observed in several patients. The anterior fontanel approach was shown to be the most useful in identifying most of the major intracranial arteries and veins with CDI. In addition, the body weights and gestational ages of the neonates were found to significantly influence the success rate in visualizing the intracranial vasculature.     

Colour Doppler imaging of arteriovenous malformation of the vein of Galen in a newborn

Summary We report a neonate with congestive heart failure due to a huge arteriovenous malformation of the vein of Galen. Two dimensional ultrasound showed a large cystic structure behind the 3rd ventricle and the quadrigeminal plate. The cyst compressed the posterior part of the 3rd ventricle and the aqueduct and caused an obstructive hydrocephalus. The diagnosis was established by colour Doppler imaging (CDI). With the help of CDI, flow within the aneurysm could be shown as well as feeding arteries originating from the posterior and middle cerebral arteries. The straight sinus and the torcular Herophili were markedly dilated.     

儿童中枢性尿崩症的影像学诊断价值

目的　评价影像学检查在儿童中枢性尿崩症的诊断价值。材料与方法　复习 14 0例儿童尿崩症的临床资料 ,对其中作过CT或MRI检查的 78例中枢性尿崩症的临床及影像学进行回顾性分析研究。结果　原发性尿崩症 5 4例 ,继发性尿崩症 2 4例。结论　儿童中枢性尿崩症中继发性尿崩症占有相当高比例 ,因此非常有必要对这些患儿进行鞍区CT或磁共振检查 ,以除外继发性尿崩症     

Crossing vessels at the ureteropelvic junction: detection with contrast-enhanced color Doppler imaging

PURPOSE: To investigate the feasibility of imaging crossing vessels at the ureteropelvic junction (UPJ) preoperatively by means of contrast agent-enhanced color Doppler imaging (CDI). MATERIALS AND METHODS: Twenty-nine patients (13 female patients, 16 male patients; age range, 17-76 years; mean age, 45 years) with symptomatic UPJ obstruction were examined with CDI before and after intravenous infusion of the contrast agent. The type (i.e., arterial or venous) and position of the vessel relative to the UPJ (i.e., anterior or posterior) were assessed. The CDI findings were correlated with the surgical findings at laparoscopic pyeloplasty. RESULTS: Among the 29 patients, crossing vessels were detected with nonenhanced CDI in 15 patients, with enhanced CDI in 22 patients, and with laparoscopy in 23 patients. Enhanced CDI depicted crossing vessels in 22 (96%) of the 23 laparoscopically confirmed cases compared with nonenhanced CDI, which depicted 15 (65%) of the 23 cases. The rate of detecting crossing vessels increased significantly with use of the contrast agent (P < .016, McNemar test). CONCLUSION: Compared with nonenhanced CDI, contrast-enhanced CDI significantly improves the detection of crossing vessels at the UPJ and is useful in the presurgical evaluation of UPJ obstruction.     

Negative D-dimer testing excludes pulmonary embolism in non-high risk patients in the emergency department

Purpose

The purpose of this study was to assess the ability of d-dimer testing to obviate the need for cross-sectional imaging for patients at “non-high risk” for pulmonary embolism (PE).

Methods

This is a retrospective study of emergency department patients at an academic medical center who underwent cross-sectional imaging (MRA or CTA) to evaluate for PE from 2008 to 2013. The primary outcome was the NPV of d-dimer testing when used in conjunction with clinical decision instruments (CDIs = Wells’, Revised Geneva, and Simplified Revised Geneva Scores). The reference standard for PE status included image test results and a 6-month chart review follow-up for venous thromboembolism as a proxy for false negative imaging. Secondary analyses included ROC curves for each CDI and calculation of PE prevalence in each risk stratum.

Results

Of 459 patients, 41 (8.9%) had PE. None of the 76 patients (16.6%) with negative d-dimer results had PE. Thus, d-dimer testing had 100% sensitivity and NPV, and there were no differences in CDI performance. Similarly, when evaluated independently of d-dimer results, no CDI outperformed the others (areas under the ROC curves ranged 0.53–0.55). There was a significantly higher PE prevalence in the high versus “non-high risk” groups when stratified by the Wells’ Score (p = 0.03).

Conclusions

Negative d-dimer testing excluded PE in our retrospective cohort. Each CDI had similar NPVs, whether analyzed in conjunction with or independently of d-dimer results. Our results confirm that PE can be safely excluded in patients with “non-high risk” CDI scores and a negative d-dimer.

     

中枢性尿崩症的MR影像诊断(附65例分析)

目的：分析中枢性尿崩症（ＣＤＩ）的ＭＲ表现，探讨ＭＲ在ＣＤＩ的影像诊断中的价值及限度。材料与方法：对１９９６－０６～１９９６－０７间所确诊的６５例ＣＤＩ患者的ＭＲ资料和临床资料进行了回顾性分析。结果：１、ＭＲ表现：鞍内／鞍上肿块１６例；垂体柄断裂或显示不清１４例；垂体柄增粗１０例；垂体柄结节５例；垂体后叶高信号消失５８例。２、引起ＣＤＩ的病因：头颅损伤６例；颅内肿瘤１７例；Ｌａｎｇｅｒｈａｎ＇ｓ组织细胞增生症２例；特发性ＣＤＩ１７例。有２３例继发性ＣＤＩ的病因未经病理证实。结论：低场强（０．３Ｔ）的ＭＲ机器能够清楚地显示下丘脑－垂体区的病变，对ＣＤＩ病因的诊断和治疗具有重要的价值，但对肿瘤及炎性病变的定性诊断有一定的限度，同时认为临床上划分的部分性ＣＤＩ和完全性ＣＤＩ的ＭＲ影像表现不存在差别。     

Real-time volumetric flow measurements with complex-difference MRI.

Blood flow in large vessels can be noninvasively evaluated with phase-contrast (PC) MRI by encoding the spin velocity to the image phase. Conventional phase-difference processing of the flow-encoded image data yields velocity images. Complex-difference processing is an alternative to phase-difference methods, and has the advantage of eliminating signal from stationary spins. In this study, two acquisitions with differential flow encoding are subtracted to yield a single projection that contains signal from only those spins moving in the direction of the flow-encoding gradients. The increase in acquisition efficiency allows real-time flow imaging with a temporal window as short as two acquisition lengths (60 ms). Validation of the complex-difference method by comparison with conventional gated-segmented PC-MRI in a flow phantom yielded a correlation of r > 0.99. Peak arterial flow rates in the popliteal artery and desending aorta measured in vivo with the complex-difference method were 0.92 +/- 0.06 of the values measured with conventional PC imaging. Real-time in vivo volumetric flow imaging of transient flow events is also presented.     

Chronic hepatitis: role of diffusion-weighted imaging and diffusion tensor imaging for the diagnosis of liver fibrosis and inflammation

PURPOSE: To determine the diagnostic performance of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation. MATERIALS AND METHODS: Breathhold single-shot echo-planar imaging CDI and DTI with b-values of 0 and 500 second/mm(2) was performed in 31 patients with chronic liver disease and 13 normal volunteers. Liver biopsy was performed in all patients with liver disease with a median delay of two days from MRI. Fibrosis and inflammation were scored on a 5-point scale (0-4). Liver ADCs obtained with CDI and DTI were compared between patients stratified by fibrosis stage and inflammation grade. Receiver operating characteristic (ROC) curve analyses were conducted to evaluate the utility of the ADC measures for prediction of fibrosis and inflammation. RESULTS: Patients with liver fibrosis and inflammation had significantly lower liver ADC than subjects without fibrosis or inflammation with CDI and DTI. For prediction of fibrosis stage > or = 1 and stage > or = 2, area under the ROC curve (AUC) of 0.848 and 0.783, sensitivity of 88.5% to 73.7%, and specificity of 73.3% to 72.7% were obtained, for ADC < or =1.40 x 10(-3) mm(2)/second and < or =1.30 x 10(-3) mm(2)/second (using CDI), respectively. For prediction of inflammation grade > or = 1, AUC of 0.825, sensitivity of 75.0%, and specificity of 78.6% were obtained using ADC < or = 1.30 x 10(-3) mm(2)/second (using CDI). CDI performed better than DTI for diagnosis of fibrosis and inflammation. CONCLUSION: Liver ADC can be used to predict liver fibrosis and inflammation with acceptable sensitivity and specificity.     

视网膜中央静脉阻塞与球后血流动力学及血液流变学的临床分析

 目的探讨视网膜中央静脉阻塞(CRVO)患者的视网膜中央动脉(CRA)、眼动脉(OA)的血液动力学、血液流变学改变及其相互关系.方法采用美国AcusN128XP/10彩色多普勒成像(CDI)技术检测33例CRVO患者和33例正常人CRA.OA血流动力学及血液流变学改变.结果CRVO患眼CRA收缩期最大血流速度(Vmax)比对侧眼(P＜0.05)及对照组(P＜0.01)下降,舒张末期最小血流速度(Vmin)比对侧眼及对照组减低(P＜0.05),阻力指数(RI)比对侧眼(P＜0.05)及对照组(P＜0.01)增高.低切率全血比粘度较对照组显著性增高(P＜0.01),并与CRAO患者Vmax(r=-0.641,P＜0.01)、Vmin(r=-0.538),P＜0.01)成负相关.结论CRVO患眼CRA的CDI参数异常,表明动脉血流速度的下降与CRVO发病相关,CRA供血减少是引起视网膜损害的主要原因之一.低切率全血比粘度增高是导致CRVO患眼CRA血流下降因素之一.     

Magnetic resonance imaging in familial central diabetes insipidus

Summary More detailed examinations of the pituitary gland in central diabetes insipidus (CDI) has been possible with magnetic resonance imaging (MRI). Compared to the high signal findings in the posterior lobes of normal subjects, the absence of such signal in adults and children with primary CDI has been reported. Familial CDI is a hereditary form of primary CDI with a variety of clinical expressions among affected individuals which is said to be related to varying degrees of an arginine vasopressin (AVP) deficiency. However, the structural correlates have yet to be documented by MRI technique. This report describes the pituitary gland MRI findings (using a superconducting magnet; 3 mm-slice thickness; spinecho, repetition time 400 ms, echo time 25 ms) in five patients in one family with familial CDI. A signal of high intensity was detected in the posterior part of the pituitary gland in 2 patients but not in 3 others. We concluded that MRI of the posterior pituitary lobe in familial CDI seem to vary in members of the same family.     

Current applications of color Doppler imaging in the abdomen and extremities

Recent advances in ultrasound technology have resulted in the development of diagnostic instruments that combine cross sectional imaging with spectral and color flow Doppler analysis. These instruments have expanded the role of diagnostic ultrasonography in the assessment of disease states involving the extracranial carotid artery, the peripheral vascular system, and the major abdominal vessels. The current applications of color Doppler imaging (CDI) combined with conventional spectral Doppler are demonstrated.     

Quantitation in positron emission tomography: 8. Effects of nonlinear parameter estimation on functional images

Functional images used in positron emission tomography (PET) have the advantage of presenting simultaneously the anatomical and functional information in cross-sectional body slices. However, the nonlinearity in parameter estimation, when combined with the finite image resolution, can cause systematic errors or biases in the estimated functional parameters. The effect of this error on blood flow images, which are commonly used in PET, is investigated in this study. Computer-simulated brain and heart phantoms of realistic configurations are used to examine the effect of various factors, such as imaging resolution, estimation nonlinearity, and structure configuration. The nonlinearity characteristics of six commonly used blood flow estimation techniques are simulated. Results show that structure boundaries on parametric images between tissues of different blood flows do not usually coincide with the true anatomical boundaries and would thus cause an apparent change in the cross-sectional size of the structures. The regional blood flow values as obtained from the blood flow images are usually lower than the true values. The severity of these effects is dependent on the characteristics of the flow estimation technique, the image resolution, and the size and shape of the structure. Although image resolution is a major factor in causing errors in the parametric images, its improvement, within the range examined in the present study [from 1.5 to 0.5 cm full width at half maximum (FWHM)], is not found to reduce drastically the underestimation of blood flow in brain phantom. The effect on boundary shift, however, is found to be in proportion to the FWHM of image resolution. Implications of these effects on generation, interpretation, and comparison of parametric/functional images are discussed.     

Nonsubtractive spiral phase contrast velocity imaging.

Phase contrast velocity imaging is a standard method for accurate in vivo flow measurement. One drawback, however, is that it lengthens the scan time (or reduces the achievable temporal resolution) because one has to acquire two or more images with different flow sensitivities and subtract their phases to produce the final velocity image. Without this step, non-flow-related phase variations will give rise to an erroneous, spatially varying background velocity. In this paper, we introduce a novel phase contrast velocity imaging technique that requires the acquisition of only a single image. The idea is to estimate the background phase variation from the flow-encoded image itself and then have it removed, leaving only the flow-related phase to generate a corrected flow image. This technique is sensitive to flow in one direction and requires 50% less scan time than conventional phase contrast velocity imaging. Phantom and in vivo results were obtained and compared with those of the conventional method, demonstrating the new method's effectiveness in measuring flow in various vessels of the body. Magn Reson Med 42:704-713, 1999.     

Automatic enhancement, animation, and segmentation of flow in peripheral arteries from MR phase-shift velocity mapping.

The authors describe a technique for automatic enhancement, segmentation, and analysis of flow from MR phase shift velocity mapping. This method uses a specific flow related enhancement process to extract and localize the flow field within the image, followed by global flow analysis. By animation on low cost equipment (personal computers), this method can provide various ways of visualizing flow in vivo and its variation in different structures and lesions. Our preliminary results using this method for analyzing flow data in the aortic bifurcation of healthy volunteers are encouraging.     

The use of color Doppler imaging for the assessment of sacroiliac joint stiffness: a study on embalmed human pelvises

Purpose: The validity and reproducibility of an instrumented dynamic examination method to measure sacroiliac (SI) joint stiffness was tested in vitro. Methods: Four embalmed human female pelvises were excitated by a pelvic vibrator. A color Doppler imaging (CDI) scanner was used to image the amplitude of vibrations at different sites of the pelvis. Vibrations were applied to the anterior superior iliac spines unilaterally and were received by CDI all over the ipsilateral SI region. Three different stability conditions were created in the SI joints: no intervention, screwed and ligaments cut. Test results were quantified by taking the minimum threshold levels of the bones. The relative difference of vibration intensity between ipsilateral ilium and sacrum at each stability condition is accepted as the stiffness level for the SI joint. Results: Statistics showed high reproducibility and significant differences between the stability conditions. Dynamic testing based on the use of vibrations provides visible and quantifiable intra- and inter-individual differences between SI joint stiffnesses. Conclusions: This new method is objective and reproducible. Future in vivo application is promising since there are no technical and safety restrictions.