Time-resolved Imaging Of Contrast Kinetics Research Articles

Time-resolved magnetic resonance imaging of contrast kinetics to identify severe tricuspid valve regurgitation

Introduction The gold standard for identifying and grading tricuspid valve regurgitation is transthoracic echocardiography. However, the acoustic window using transthoracic echocardiography is not always suffi cient to quantify the amount of regurgitation. Time-resolved imaging of contrast kinetics (TRICKS) is a 4-dimensional magnetic resonance angiography option with high spatial and temporal resolution. The aim of the present study is to fi nd out whether identifi cation of patients with severe tricuspid valve regurgitation by using TRICKS angiography is feasible.Methods TRICKS angiography was performed in a 3T-CMR-scanner after antecubital injection of gadolinium dimeglumine during breath hold. Retrograde appearance of contrast agent in the hepatic veins was classifi ed as severe tricuspid regurgitation (TR). Additional semi quantifi cation of retrograde perfusion was performed by temporal signal intensity curve (SIC) analysis in the hepatic veins close to their drainage into the inferior vena cava. Transthoracic echocardiography (TTE) using the actual European guidelines on the management of valvular heart disease served as gold standard for TR grading.Results 185 patients (57 ± 17 years) with TR ranging from no to severe TR were analysed prospectively. 14 (7.6%) patients had severe TR, 27 (14.6%) showed moderate, 137 (74.1%) mild and 7 (3.8%) no TR. TRICKSangiography identifi ed 13 patients with retrograde contrast appearance in the hepatic veins, of whom all had severe TR in TTE. No patient with echocardiographic mild or moderate TR was graded as severe TR using TRICKSangiography. One patient with echocardiographic severe TR showed neither in the visual analysis nor in SIC analysis retrograde appearance of contrast agent in the hepatic veins. Overall, the sensitivity for detecting severe TR using TRICKSangiography was 93% with a specifi city of 100%. The positive predictive value was 100%, the negative predictive value 99%. For severe TR there was no intra- and interobserver variability.Conclusion MR TRICKSangiography is a very reliable tool to identify patients with severe TR by the imaging of retrograde appearance of contrast agent in the hepatic veins. Sensitivity and specifi city of this approach is very high with no intra- and interobserver variability.

Qualitative analysis of the elliptical centric technique and the TRICKS technique

This study evaluated the usefulness of time resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography (MRA) and elliptical centric MRA according to the type of cerebral disease. From February 2010 to January 2012, elliptical centric MRA and TRICKS MRA images were acquired from 50 normal individuals and 50 patients with cerebral diseases by using 3.0-Tesla magnetic resonance imaging (MRI) equipment. The images were analyzed qualitatively by examining areas such as the presence or absence of artifacts on the images, the distinctness of boundaries of blood vessels, accurate representation of the lesions, and the subtraction level. In addition, the sensitivity, specificity, positive prediction rate, negative prediction rate and accuracy were assessed by comparing the diagnostic efficacy of the two techniques. The results revealed TRICKS MRA to have superior image quality to elliptical centric MRA. Regarding each disease, TRICKS MRA showed higher diagnostic efficacy for artery venous malformation (AVM) and middle cerebral artery (MCA) bypass patients whereas elliptical centric MRA was more suitable for patients with brain tumors, cerebral infarction, cerebral stenosis or sinus mass.

La classification histopathologique simplifiée des tumeurs présentée à l’aide d’un outil pédagogique collaboratif en ligne en mode zoom

To evaluate feasibility and image quality of time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium–pulmonary veins (LA–PV) complex with half dose of intravenous gadolinium-based contrast agent (GBCA) in patients candidate to percutaneous radiofrequency ablation of atrial fibrillation.Fifty-seven patients underwent CEMRA of the LA–PV complex on a 1.5 T MRI scanner. On 24/57 patients, a conventional fast-spoiled gradient-echo (FSPGR) CEMRA acquisition was run using 0.2 mL/kg of 0.5 M GBCA at 2 mL/s flow rate (protocol A), while in 33/57 patients a time-resolved multiphase CEMRA sequence (Time-Resolved Imaging of Contrast KineticS, TRICKS) was performed after intravenous injection of 0.1 mL/kg of the same GBCA at 3 mL/s flow rate (protocol B). Contrast enhancement was measured in the LA (LAe) and in the PA (PAe), and the LAe/PAe ratio was calculated. Diagnostic quality of Maximum Intensity Projection (MIP), Volume Rendering (VR), and Virtual Endoscopy (VE) reconstructions was also assessed visually using a semiquantitative score.LAe was comparable with both protocols, while PAe was lower with protocol B than with protocol A (p = 0.0217). Moreover, the LAe/PAe ratio was significantly higher with protocol B than with protocol A (p = 0.0044).Finally, image quality of MIP, VR, and VE reconstructions was significantly better with protocol B than with protocol A (p = 0.0005, p = 0.0001, and p = 0.005, respectively).CEMRA of the LA–PV complex is feasible with TRICKS and half-dose GBCA and yields better separation between the LA–PV complex and the PA, as well as better image quality of MIP, VR, and VE reconstructions than a conventional FSPGR sequence performed with full GBCA dose.

Clinical Usefulness of Orbital and Facial Time-Resolved Imaging of Contrast KineticS (TRICKS) Magnetic Resonance Angiography

The clinical usefulness of orbital and facial Time-Resolved Imaging of Contrast KineticS (TRICKS) MRI was assessed quantitatively and qualitatively. A retrospective chart review of the years 2001 to 2011 was conducted at the University of Wisconsin, Madison. Patients were selected based on tumor location (extracranial head and neck) and evaluation with TRICKS imaging at any stage of the clinical course. The TRICKS protocol presented in this article allows measurement of specific tumor characteristics including lesion morphology, vascular anatomy, flow dynamics within the lesion, rapidity and sequential nature of contrast enhancement, and lesion distensibility. Cases involving changes in diagnoses and/or management as a result of TRICKS interpretation are presented in detail. The imaging records of 49 patients were reviewed. Most lesions were located in or around the orbit (32 lesions, 65%). Benign vascular tumors comprised the largest subcategory (32 lesions, 65%) in the cohort. Of the 20 cases with histopathological data, interpretation of MRI with TRICKS magnetic resonance angiography successfully predicted 17 (85%). Characteristic enhancement patterns for the most commonly encountered lesions are presented, in addition to a qualitative analysis of how TRICKS contributed to select cases. TRICKS helped clarify diagnosis and/or redirect management in 19 of the 49 cases in this series. To the best of the authors' knowledge, this is the largest study to date of patients evaluated with TRICKS MRI/magnetic resonance angiography for orbital and facial tumors. MRI with TRICKS magnetic resonance angiography imaging protocol offers a minimally invasive, safe, and effective diagnostic instrument in selected patients with clinical diagnostic uncertainty and in those patients requiring high-resolution vascular mapping for management planning.

Time‐resolved angiography: Past, present, and future

The introduction of digital subtraction angiography (DSA) in 1980 provided a method for real time 2D subtraction imaging. Later, 4D magnetic resonance (MR) angiography emerged beginning with techniques like Keyhole and time-resolved imaging of contrast kinetics (TRICKS) that provided frame rates of one every 5 seconds with limited spatial resolution. Undersampled radial acquisition was subsequently developed. The 3D vastly undersampled isotropic projection (VIPR) technique allowed undersampling factors of 30-40. Its combination with phase contrast displays time-resolved flow dynamics within the cardiac cycle and has enabled the measurement of pressure gradients in small vessels. Meanwhile similar accelerations were achieved using Cartesian acquisition with projection reconstruction (CAPR), a Cartesian acquisition with 2D parallel imaging. Further acceleration is provided by constrained reconstruction techniques such as highly constrained back-projection reconstruction (HYPR) and its derivatives, which permit acceleration factors approaching 1000. Hybrid MRA combines a separate phase contrast, time-of flight, or contrast-enhanced acquisition to constrain the reconstruction of contrast-enhanced time frames providing exceptional spatial and temporal resolution and signal-to-noise ratio (SNR). This can be extended to x-ray imaging where a 3D DSA examination can be used to constrain the reconstruction of time-resolved 3D volumes. Each 4D DSA (time-resolved 3D DSA) frame provides spatial resolution and SNR comparable to 3D DSA, thus removing a major limitation of intravenous DSA. Similar techniques have provided the ability to do 4D fluoroscopy.

Maximizing time-resolved MRA for differentiation of hemangiomas, vascular malformations and vascularized tumors

Contrast-enhanced magnetic resonance angiography (MRA) using time-resolved imaging is a relatively new and increasingly popular technique. We will describe the technique utilized at our institution, Time-Resolved Imaging of Contrast Kinetics (TRICKS; GE Healthcare, Milwaukee, WI), and the parameters that can be adjusted to optimize the exam. We will review key imaging features of hemangiomas and vascular malformations in various modalities, with a special emphasis on the TRICKS appearance.

Time-resolved imaging of contrast kinetics does not improve performance of follow-up MRA of embolized intracranial aneurysms

SummaryBackgroundThe use of contrast media and the time-resolved imaging of contrast kinetics (TRICKS) technique have some theoretical advantages over time-of-flight magnetic resonance angiography (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular treatment. We prospectively compared the diagnostic performance of TRICKS and TOF-MRA with digital subtracted angiography (DSA) in the assessment of occlusion of embolized aneurysms.Material/MethodsSeventy-two consecutive patients with 72 aneurysms were examined 3 months after embolization. Test characteristics of TOF-MRA and TRICKS were calculated for the detection of residual flow. The results of quantification of flow were compared with weighted kappa. Intraobserver and interobserver reproducibility was determined.ResultsThe sensitivity of TOF-MRA was 85% (95% CI, 65–96%) and of TRICKS, 89% (95% CI, 70–97%). The specificity of both methods was 91% (95% CI, 79–98%). The accuracy of the flow quantification ranged from 0.76 (TOF-MRA) to 0.83 (TRICKS). There was no significant difference between the methods in the area under the ROC curve regarding both the detection and the quantification of flow. Intraobserver reproducibility was very good with both techniques (kappa, 0.86–0.89). The interobserver reproducibility was moderate for TOF-MRA and very good for TRICKS (kappa, 0.74–0.80).ConclusionsIn this study, TOF-MRA and TRICKS presented similar diagnostic performance; therefore, the use of time-resolved contrast-enhanced MRA is not justified in the follow-up of embolized aneurysms.

Time-resolved MR angiography of the intracranial venous system: an alternative MR venography technique

To compare time-resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography (MRA) with two-dimensional time-of-flight (TOF) magnetic resonance venography (MRV), and three-dimensional contrast-enhanced (CE) MRV in the visualisation of normal cerebral veins and dural venous sinuses. This prospective study consisted of 35 consecutive patients. All patients were examined with TOF MRV, TRICKS MRA and CE MRV; a single dose of intravenous contrast material was administered for the last two sequences. The image quality of these techniques was assessed and compared qualitatively (by a semiquantitative scoring system) and quantitatively (by calculating signal-to-noise ratios [SNRs] and contrast-to-noise ratios [CNRs]). Left transverse sinus, left sigmoid sinus, bilateral thalamostriate veins and Trolard veins were better visualised by TRICKS MRA and CE MRV compared with TOF MRV (P < 0.05). For left thalamostriate vein visualisation, TRICKS MRA was inferior to CE MRV (P < 0.05). With quantitative analysis the SNRs and CNRs were highest at TRICKS MRA, which was followed by CE MRV and TOF MRV (P < 0.05). Despite its limited spatial resolution, TRICKS MRA is comparable to static CE MRV and better than TOF MRV in the visualisation of normal dural sinuses and cerebral veins. • Time resolved magnetic resonance angiography can image the intracranial venous system dynamically • It seems comparable to contrast-enhanced MRV techniques in venous visualisation • The optimal phase for venous structures can be chosen from the dynamic data set • The diagnostic performance in venous thrombosis requires further research.

Time-resolved MR angiography of the calf arteries using a phased array cardiac coil: comparison of visibility with standard three-step bolus chase MR angiography

Standard bolus chase MR angiography (MRA) is increasingly replacing digital subtraction angiography (DSA) in the diagnostic evaluation of peripheral vascular disease. However, a major limitation of bolus chase MRA is the relatively poor visibility of the calf arteries. To evaluate the feasibility of visualizing the calf arteries and the visibility quality of an 8-channel cardiac phased array coil using time-resolved imaging of contrast kinetics (TRICKS) MRA compared with standard bolus chase MRA on a 1.5 Tesla MRI scanner. MRA findings of 59 sequential patients (mean age 57.8 years, range 14-83 years; 41 men) were retrospectively evaluated. All examinations included preliminary TRICKS for the lower leg using a surface 8-channel cardiac coil, followed by a 3-step MRA of the abdominal aorta, thigh, and lower leg using a body coil. Images yielded by both methods were separately evaluated by consensus of two radiologists unaware of the patients' clinical data. Visibility of the calf arteries (popliteal, tibialis anterior, tibialis posterior, tibioperoneal trunk, and peroneal) for both sides was subjectively classified as 'diagnostic' or 'non-diagnostic'. Descriptive statistics for image diagnostic quality were assessed. A total of 575 calf arterial segments were evaluated. Visibility of all calf arteries was significantly better with TRICKS than with the standard bolus chase MRA (P < 0.001). The improvement of calf artery visibility with TRICKS was more pronounced in patients with peripheral vascular disease compared to those with arteritis, vascular malformation and popliteal entrapment syndrome. Using a cardiac coil for MRA of the lower extremities resulted in visibility comparable to that of a dedicated leg coil, with diagnostic superiority for the TRICKS method compared to the standard bolus chase method.

Evaluation of spinal dural arteriovenous fistulae with gadofosveset trisodium at 3 T (TRICKS and LAVA)

Spinal dural arteriovenous fistulae (DAVF) are rare, acquired lesions that constitute 1e2% of vascular neurological pathologies. Themost reliable method for evaluation of small calibre spinal vessels is catheter angiography.1 This technique is relatively hazardous in patients who have significant atherosclerotic disease and unfavourable vascular anatomy, especially at the thoracic spinal level. There is potential for aortic dissection or thrombo-embolic complications.2 Magnetic resonance imaging (MRI) has been widely applied in the evaluation of patients with suspected DAVF. Initially, the diagnosis was based upon changes in cord appearance and not on the visualization of the vessels themselves.3 MRI has been suggested as the initial investigation of choice followed by selective catheter angiography, which is more accurate in diagnosing, localizing, and classifying spinal DAVF.4 To the authors’ knowledge no previous reports exist on the evaluation of DAVF with the blood-pool contrast agent gadofosveset trisodium at 3T. The present report describes TRICKS (time-resolved imaging of contrast kinetics) and LAVA (liver acquisition with volume acceleration) sequences, which were found very useful in the management of this relatively uncommon condition.

Posterior fossa dural arteriovenous fistulas: diagnosis and follow-up with time-resolved imaging of contrast kinetics (TRICKS) at 1.5T

Time-of-flight MR angiography (TOF MRA) is currently the most widely used non-invasive imaging tool to diagnose dural arteriovenous fistula (DAVF). It is, however, not as sensitive as invasive digital subtraction angiography (DSA) for detecting the arteriovenous shunting inherent in DAVF. Dynamic contrast-enhanced MR angiography allows separation of arterial and venous phases of contrast passage though the brain and can thus demonstrate early venous filling through the arteriovenous shunt. To compare the diagnostic value of TOF MRA and a commercially available dynamic contrast-enhanced MR angiography sequence (TRICKS) at 1.5T in detecting posterior fossa DAVF. We retrospectively collected image data for 19 patients who underwent TOF MRA, TRICKS, and DSA either for primary diagnosis or for follow-up of posterior fossa DAVF and assessed the performance of TOF MRA and TRICKS in demonstrating the arteriovenous shunt, with DSA as the reference standard. TRICKS detected early arterial filling at 94.4% sensitivity and 83.3% specificity. TOF MRA detected high flow-related signal within venous structures at 64.7% sensitivity and 80% specificity. The commercially available dynamic MR angiography sequence TRICKS with fully automatic vendor postprocessing at 1.5T is more sensitive than TOF MRA in detecting the arteriovenous shunt in posterior fossa DAVF.

Time-resolved contrast-enhanced magnetic resonance angiography in the investigation of suspected intracranial dural arteriovenous fistula

Cerebral angiography is widely regarded as the gold standard for the evaluation and diagnosis of neurovascular abnormalities. However, recent improvements in the spatial and temporal resolution of time-resolved magnetic resonance angiography (MRA) offer clinicians a non-invasive alternative to cerebral angiography. We explored the utility of this technique in an elderly female patient with a suspected intracranial dural arteriovenous fistula (dAVF). A product pulse sequence available from the scanner’s manufacturer (time-resolved imaging of contrast kinetics, TRICKS; GE Healthcare, Milwaukee, WI, USA) was used with the following parameters: TR/TE 2.832/TE 1.072 ms, flip angle 25°, receiver bandwidth 31.25 kHz, 0.75 NEX, acceleration factor (ASSET) of 2, field of view 14 cm, matrix size 96 × 96, phase-encoding left-right. Twenty overlapping 8-mm-thick slices were acquired in an axial orientation, with a slice spacing of 4 mm. Images were acquired at 48 time points, with a temporal resolution of 0.3 s/image. We found that all intracranial venous structures enhanced synchronously. There was no evidence of arteriovenous shunting. Retrograde venous flow explained the signal abnormality seen on time-of-flight MRA. We concluded that time-resolved MRA is useful in the investigation of suspected intracranial dAVF.

Usefulness of contrast-enhanced three-dimensional MR angiography using time-resolved imaging of contrast kinetics applied to description of Extracranial Arteriovenous Malformations: Initial Experience

The purpose of this study was to evaluate the usefulness of contrast-enhanced three-dimensional MR angiography using time-resolved imaging of contrast kinetics (TRICKS-MRA) to demonstrate extracranial arteriovenous malformations (E-AVMs). TRICKS-MRA was performed in 33 patients (adults; n = 30, children; n = 3) with E-AVMs. Four different scan protocols were arranged based on the size of E-AVM, and serial images were acquired from the start of contrast injection with a time frame ranging from 1.2 to 7.1s. Demonstration of feeding arteries and drainage veins, and the extent of nidus was qualitatively graded using a three-point scale. In sixteen patients who underwent DSA 3 days to 15 months after TRICKS-MRA, the comparability of TRICKS-MRA to DSA was evaluated using a three-point scale. In each category, score of 3 or excellent was defined as the positive result. Demonstration of the feeding arteries, the drainage veins, and the extent of nidus were graded as excellent in 68%, 65%, and 58% of the patients, respectively. Comparability of TRICKS-MRA to DSA was excellent in 75%, 88%, and 88% of the sixteen patients who underwent DSA. TRICKS-MRA is a feasible and useful vascular imaging technique to provide time-resolved analysis of angioarchitecture of E-AVMs.

Time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium–pulmonary veins complex with half dose of intravenous gadolinium-based contrast agent. Technical feasibility and comparison with a conventional CEMRA, full contrast dose protocol

To evaluate feasibility and image quality of time-resolved contrast-enhanced magnetic resonance angiography (CEMRA) of the left atrium-pulmonary veins (LA-PV) complex with half dose of intravenous gadolinium-based contrast agent (GBCA) in patients candidate to percutaneous radiofrequency ablation of atrial fibrillation. Fifty-seven patients underwent CEMRA of the LA-PV complex on a 1.5T MRI scanner. On 24/57 patients, a conventional fast-spoiled gradient-echo (FSPGR) CEMRA acquisition was run using 0.2 mL/kg of 0.5M GBCA at 2 mL/s flow rate (protocol A), while in 33/57 patients a time-resolved multiphase CEMRA sequence (Time-Resolved Imaging of Contrast KineticS, TRICKS) was performed after intravenous injection of 0.1 mL/kg of the same GBCA at 3 mL/s flow rate (protocol B). Contrast enhancement was measured in the LA (LAe) and in the PA (PAe), and the LAe/PAe ratio was calculated. Diagnostic quality of Maximum Intensity Projection (MIP), Volume Rendering (VR), and Virtual Endoscopy (VE) reconstructions was also assessed visually using a semiquantitative score. LAe was comparable with both protocols, while PAe was lower with protocol B than with protocol A (p = 0.0217). Moreover, the LAe/PAe ratio was significantly higher with protocol B than with protocol A (p = 0.0044). Finally, image quality of MIP, VR, and VE reconstructions was significantly better with protocol B than with protocol A (p = 0.0005, p = 0.0001, and p = 0.005, respectively). CEMRA of the LA-PV complex is feasible with TRICKS and half-dose GBCA and yields better separation between the LA-PV complex and the PA, as well as better image quality of MIP, VR, and VE reconstructions than a conventional FSPGR sequence performed with full GBCA dose.

Use of MR Venography for Characterization of the Extracranial Venous System in Patients with Multiple Sclerosis and Healthy Control Subjects

To investigate the differences in the extracranial venous system in patients with multiple sclerosis (MS) and healthy control (HC) subjects by using magnetic resonance (MR) venography. This HIPAA-compliant, prospective study was approved by the local institutional review board, and all participants gave informed consent. Fifty-seven patients, 41 (72%) with relapsing-remitting MS and 16 (28%) with secondary-progressive MS, and 21 HC subjects were imaged with a 3-T MR unit by using two-dimensional (2D) time-of-flight (TOF) and three-dimensional (3D) time-resolved imaging of contrast kinetics (TRICKS) sequences. In addition, six MS patients and six HC subjects underwent two sequential MR venographic examinations during 1 week to test image-reimage reproducibility. The morphologic features of internal jugular vein flow were classified as absent, pinpoint, flattened, crescentic, or ellipsoidal flow. Only absent and pinpoint flow were considered abnormal. The flow of the vertebral veins was classified as absent or present. The prominence of collateral neck veins and venous asymmetries between the left and right sides were assessed. Differences among groups were tested with a two-tailed Mann-Whitney two-sample rank-sum test. No significant differences in morphologic features of flow in the internal jugular veins and vertebral veins were found between MS patients and HC subjects in any of the examined MR venographic parameters. No differences in asymmetry or prominence were found between MS patients and HC subjects. There was modest agreement (κ = 0.67) between 2D TOF and 3D TRICKS sequences. Image-reimage reproducibility showed modest agreement (κ = 0.66) for 2D TOF and low agreement for 3D TRICKS (κ = 0.33). No significant differences in the extracranial venous systems between MS patients and HC subjects were detected by using MR venography. Standardized guidelines are needed to define parameters for the presence of venous anomalies.

A general dual-bolus approach for quantitative DCE-MRI

Purpose To present a dual-bolus technique for quantitative dynamic contrast-enhanced MRI (DCE-MRI) and show that it can give an arterial input function (AIF) measurement equivalent to that from a single-bolus protocol. Methods Five rabbits were imaged using a dual-bolus technique applicable for high-resolution DCE-MRI, incorporating a time resolved imaging of contrast kinetics (TRICKS) sequence for rapid temporal sampling. AIFs were measured from both the low-dose prebolus and the high-dose main bolus in the abdominal aorta. In one animal, TRICKS and fast spoiled gradient echo (FSPGR) acquisitions were compared. Results The scaled prebolus AIF was shown to match the main bolus AIF, with 95% confidence intervals overlapping for fits of gamma-variate functions to the first pass and linear fits to the washout phase, with the exception of one case. The AIFs measured using TRICKS and FSPGR were shown to be equivalent in one animal. Conclusion The proposed technique can capture even the rapid circulation kinetics in the rabbit aorta, and the scaled prebolus AIF is equivalent to the AIF from a high-dose injection. This allows separate measurements of the AIF and tissue uptake curves, meaning that each curve can then be acquired using a protocol tailored to its specific requirements.

Time-resolved imaging of contrast kinetics three-dimensional (3D) magnetic resonance venography in patients with pelvic congestion syndrome

The purpose of this study was to assess the role of magnetic resonance venography (MRV) with time-resolved imaging of contrast kinetics (TRICKS) in dynamically evaluating ovarian vein dilation, reflux and direction of flow in patients with suspected pelvic congestion syndrome (PCS). The hypotheses tested were: (i) That conspicuity scores of the ovarian veins across three raters was greater using TRICKS MRV compared with T2W or T(2)* imaging; (ii) That three key MR variables (ovarian vein diameter, timing and grade of reflux) correlated across all raters. We carried out a retrospective study of 13 patients undergoing T2W and TRICKS MRI and pelvic sonography (n = 4) or catheter venography (n = 5). Three observers rated conspicuity, vessel diameter, timing and grade of ovarian vein reflux for T(2)/T2*W and TRICKS MRI. The mean left ovarian diameter for all patients with reflux was 7.9 mm (range 2.2-12 mm). There was high inter-observer agreement for ovarian vein diameter for both sequences. TRICKS showed significantly greater conspicuity than T(2)/T2*W imaging (TRICKS: T(2)/T2* mean (SD) = 7.80 (3.20):5.50 (1.97), F (1,12) = 5.80, p < 0.05). TRICKS MRV demonstrated high inter-observer correlation for timing and grade of reflux (r (36) = 0.77,0.71,0.79, p < 0.01). TRICKS MRA/V was significantly degraded by breathing artefact in two patients. We conclude that TRICKS MRV accurately and dynamically demonstrates ovarian vein reflux in patients with PCS but requires quiet respiration. TRICKS MRV has better image conspicuity than T(2)/T2*W imaging and sufficient temporal resolution to distinguish between Grade I, II and III reflux.

Spontaneous Resolution of Two Dural Carotid-Cavernous Fistulas Presenting With Optic Neuropathy and Marked Congestive Ophthalmopathy

Two patients with dural carotid-cavernous fistulas (CCFs) presented with optic neuropathy and marked congestive ophthalmopathy, including 1 patient with a narrowed anterior chamber angle due to choroidal effusions. Endovascular intervention was planned but deferred for logistic reasons. While the patients awaited the procedures, the clinical features markedly improved, and time-resolved imaging of contrast kinetics (TRICKS) MRA was consistent with closure of the CCFs. These patients serve as a reminder that spontaneous resolution may occur in dural CCFs even when presenting clinical features are florid and vision appears to be threatened. In fact, a rapid worsening of clinical manifestations may be a sign that a dural CCF is about to close spontaneously.

Arterial imaging in patients with lower extremity ischemia and diabetes mellitus

Precise, comprehensive imaging of the arterial circulation is the cornerstone of successful revascularization of the ischemic extremity in patients with diabetes mellitus. Arterial imaging is challenging in these patients because the disease is often multisegmental with a predilection for the distal tibial and peroneal arteries. Occlusive lesions and the arterial wall itself are often calcified and patients presenting with ischemic complications frequently have underlying renal insufficiency. Intra-arterial digital subtraction angiography (DSA), contrast enhanced magnetic resonance angiography (MRA), and more recently, computerized tomographic angiography (CTA) have been used as imaging modalities in lower extremity ischemia. Each has specific advantages and shortcomings in this patient population, which will be summarized and contrasted in this review. DSA is an invasive technique most often performed from a femoral arterial puncture and requires the injection of arterial contrast, which can occasionally cause allergic reactions. In patients with pre-existing renal insufficiency, contrast infusion can result in worsening renal failure; although usually self-limited, it may occasionally require hemodialysis, especially in patients with diabetes. However, DSA provides the highest degree of spatial resolution and image quality. It is also the only modality in which the diagnosis and treatment of arterial disease can be performed simultaneously. MRA is noninvasive, and when enhanced with gadolinium contrast injection provides arterial images of comparable quality to DSA and in some circumstances may uncover distal arterial targets not visualized on DSA. However, spatial resolution is inferior to DSA and erroneous interpretations due to acquisition artifacts are common. Specialized equipment and imaging techniques are necessary to minimize their occurrence in the distal lower extremity. In addition, due to the risk of inducing nephrogenic systemic fibrosis, gadolinium-enhanced MRA cannot be used in patients with renal insufficiency. CTA is noninvasive and rapidly performed, with better spatial resolution than MRA, but requires the largest volume of contrast infusion, exposes patients to high-doses of radiation, and is subject to interpretive error due to reconstruction artifacts especially in heavily calcified arteries, limiting its usefulness in many patients with diabetes. For patients in whom the planned intervention is a surgical bypass, DSA and MRA will provide high quality images of the lower extremity arterial anatomy. For patients in whom a catheter-based intervention is the likely treatment, a diagnostic DSA immediately followed by a catheter-based treatment in the same procedure is the preferred approach. In patients with pre-existing renal dysfunction, in which gadolinium-enhanced MRA is contraindicated, DSA or CTA can be performed. However, patients should have an infusion of intravenous normal saline solution or sodium bicarbonate before the procedure to reduce the incidence of contrast-induced nephropathy.

Traumatic Lateral Plantar Artery Pseudoaneurysm and the Use of Time-Resolved MR Angiography

Vascular injury resulting in pseudoaneurysm formation in the plantar aspect of the foot is an uncommon injury after trauma. Such injuries are more often reported in the lateral plantar artery rather than the medial plantar artery, most likely because of its more superficial location. Traditional modalities in diagnosis have included ultrasound and digital subtraction angiography. We present a case of traumatic pseudoaneurysm of the lateral plantar artery following a foot laceration. Diagnosis was made by the use of high-resolution, time-resolved contrast-enhanced 3D magnetic resonance angiography, also referred to as "TRICKS" (time-resolved imaging of contrast kinetics). This technique provided high spatial resolution for the arterial anatomy as well as temporal resolution which allowed better delineation of the hemodynamic characteristics of the pseudoaneurysm. The online version of this article (doi:10.1007/s11420-010-9170-3) contains supplementary material, which is available to authorized users.