Time-resolved Imaging Of Contrast Kinetics Research Articles

Dynamic processes of positive/negative immune-vascular crosstalk loop via functional MRI-guided monitor

Immunotherapy holds significant promise to completely eliminate tumor, yet lack of timely evaluation of immune responses, which challenged by inherent lagging and pseudoprogression during immunotherapy. Immune-vascular crosstalk (IVC), an enhancement ring for the mutual regulation linking tumor vascular normalization with immune remodeling forms, emerging as a systematic indicator for immunotherapy outcomes, necessitates timely, non-invasive, and early detection of its status to enhance clinical benefits. Herein, positive and negative loop models of tumor IVC were established using different degree of photothermal therapy (PTT) based on NaBiF4:Gd@PDA@PEG nanoprobes. Multi-functional magnetic resonance imaging, including fast spoiled gradient-recalled (FSPGR), time-resolved imaging of contrast kinetics (TRICKs) and dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI), was applied to dynamically reflect normalized/ablated tumor vasculature, well-matched increased/decreased immune response corresponding to different status of IVC, confirmed by pathology results. This study proposes a novel biological method to noninvasively detect the positive/negative IVC loop, paving the visualized way for immunotherapy assessed benefits, which is expected to be extended to clinical translation.

Inverse Problem Algorithm-Based Time-Resolved Imaging of Head and Neck Computed Tomography Angiography Contrast Kinetics with Clinical Testification.

This study mitigated the challenge of head and neck CT angiography by IPA-based time-resolved imaging of contrast kinetics. To this end, 627 cerebral hemorrhage patients with dizziness, brain aneurysm, stroke, or hemorrhagic stroke diagnosis were randomly categorized into three groups, namely, the original dataset (450), verification group (112), and in vivo testified group (65), in the Affiliated BenQ Hospital of Nanjing Medical University. In the first stage, seven risk factors were assigned: age, CTA tube voltage, body surface area, heart rate per minute, cardiac output blood per minute, the actual injected amount of contrast media, and CTA delayed trigger timing. The expectation value of the semi-empirical formula was the CTA number of the patient's left artery (LA). Accordingly, 29 items of the first-order nonlinear equation were calculated via the inverse problem analysis (IPA) technique run in the STATISTICA 7.0 program, yielding a loss function and variance of 3.1837 and 0.8892, respectively. A dimensionless AT was proposed to imply the coincidence, with a lower AT indicating a smaller deviation between theoretical and practical values. The derived formula was confirmed for the verification group of 112 patients, reaching high coincidence, with average ATavg and standard deviation values of 3.57% and 3.06%, respectively. In the second stage, the formula was refined to find the optimal amount of contrast media for the CTA number of LA approaching 400. Finally, the above procedure was applied to head and neck CTA images of the third group of 65 patients, reaching an average CTA number of LA of 407.8 ± 16.2 and finding no significant fluctuations.

MRI and MR angiography evaluation of pulsatile tinnitus: A focused, physiology-based protocol.

Pulsatile tinnitus (PT) is the subjective sensation of a pulse-synchronous sound, most often due to a cerebrovascular etiology. PT can severely impact quality of life and may indicate a life-threatening process, yet a timely and accurate diagnosis can often lead to effective treatment. Clinical assessment with a history and physical examination can often suggest a diagnosis for PT, but is rarely definitive. Therefore, PT should be evaluated with a comprehensive and targeted radiographic imaging protocol. MR imaging provides a safe and effective means to evaluate PT. Specific MR sequences may be used to highlight different elements of cerebrovascular anatomy and physiology. However, routine MR evaluation of PT must comply with economic and practical constraints, while effectively capturing both common and rarer, life-threatening etiologies of PT. In this state-of-the-art review, we describe our institutional MR protocol for evaluating PT. This protocol includes the following dedicated sequences: time-of-flight magnetic resonance angiography; arterial spin labeling; spoiled gradient recalled acquisition in the steady state; time-resolved imaging of contrast kinetics; diffusion weighted imaging, and 3-dimensional fluid-attenuated inversion recovery. We describe the physiologic and clinical rationale for including each MR sequence in a comprehensive PT imaging protocol, and detail the role of MR within the broader evaluation of PT, from clinical presentation to treatment.

The Accuracy of the TRICKS MRI in Diagnosing and Localizing a Spinal Dural Arteriovenous Fistula: A Feasibility Study

Spinal vascular malformations (SVMs) are a heterogenous group of vascular abnormalities. The gold standard for diagnosis of SVMs is spinal digital subtraction angiography (DSA), which can be challenging because of the large number of segmental arteries that need to be catheterized and the limitations in term of contrast volume used and fluoroscopy time. We describe and compare the use of the time-resolved imaging of contrast kinetics (TRICKS) sequence and DSA in the diagnosis of spinal dural arteriovenous fistulas (SDAVFs) in our institution. This is a retrospective cohort study of 27 patients who had a TRICKS MRI followed by a DSA for the diagnosis of their SDAVFs between November 2003 and November2021. A total of 19 (70.4%) patients were positive for a SDAVF on both TRICKS MRI and DSA. Out of those 19, 9 (47.4%) were in the exact location on both TRICKS MRI and DSA whereas 10 (52.6%) were in different locations. With respect to the 10 patients who had discrepancies in their SDAVF localization between the 2 modalities, 9 (90%) patients had a 1-level difference and 1 (10%) had a 2-level difference. TRICKS MRI represents an accurate screening tool to be performed before a spinal DSA in order to guide the interventionalist to focus on the correct level ±2 levels; this extra noninvasive screening tool will decrease the risk of a kidney injury from an overuse of contrast and minimize the fluoroscopy/radiation overexposure.

A Preliminary Study of Gadobenate Dimeglumine Enhanced Magnetic Resonance Angiography Detection of Prostatic Artery Anatomy

Background: To describe the feasibility of anatomy and imaging findings of the prostatic arteries (PAs) on contrast-enhanced MR angiography (ce-MRA). Methods: This prospective study enrolled 7 patients undergoing pelvic 3.0 T ce-MRA and selective pelvic digital subtraction angiography before prostatic artery embolization (PAE). Four patients underwent fluoroscopically triggered ce-MRA and 3 patients underwent time-resolved imaging of contrast kinetics. PAE was performed within one week of MRA. Two radiologists independently analyzed MRA findings. The analyzed parameters included the number of independent PAs and their origin, trajectory, and anastomoses with adjacent arteries. Image quality in terms of signal-to-noise ratio (SNR) and contrast-tonoise ratio (CNR) to visualize common iliac artery and its branches including prostatic arteries was compared between the two groups. Results: A total of 17 PAs were demonstrated in 7 cases. The diagnostic accuracy of MRA in detecting bilateral PAs was 58.82%. Moreover, 71.42% of the patients had only one PA in one side, and 7.14% had independent PAs. The mean diameter of 10 PAs was 1.39 ± 0.46 mm. About 29.41% of PAs originated from the obturator arteries and 29.41% from the pudendal arteries. Bilateral PAs were found to be symmetric in 3 cases and asymmetric in 4 cases. No significance difference was found between the image quality of the two groups, except for the signal intensity of the right common iliac artery and right internal iliac artery and SNR and CNR of the left common iliac artery. Conclusions: This study shows that ce-MRA is able to detect PA, and can provide guidance for PAE.

Measurement of murine kidney functional biomarkers using DCE-MRI: A multi-slice TRICKS technique and semi-automated image processing algorithm

PurposeTo propose a rapid multi-slice T1 measurement method using time-resolved imaging of contrast kinetics (TRICKS) and a semi-automated image processing algorithm for comprehensive assessment murine kidney function using dynamic contrast-enhanced MRI (DCE-MRI). MethodsA multi-slice TRICKS sampling scheme was implemented in an established rapid T1 measurement method. A semi-automated image-processing scheme employing basic image processing techniques and machine learning was developed to facilitate image analysis. Reliability of the multi-slice technique in measuring renal perfusion and glomerular filtration rate (GFR) was tested in normal mice (n = 7 for both techniques) by comparing to the validated single-slice technique. Utility of this method was demonstrated on mice after either sham surgery (n = 7) or induction of unilateral renal artery stenosis (RAS, n = 8). Renal functional parameters were extracted using a validated bi-compartment model. ResultsThe TRICKS sampling scheme achieved an acceleration factor of 2.7, allowing imaging of eight axial slices at 1.23 s/scan. With the aid of the semi-automated scheme, image analysis required under 15-min for both kidneys per mouse. The multi-slice technique yielded renal perfusion and GFR values comparable to the single-slice technique. Model-fitted renal parameters successfully differentiated control and stenotic mouse kidneys, including renal perfusion (706.5 ± 164.0 vs. 375.9 ± 277.9 mL/100 g/min, P = 0.002), blood flow (1.6 ± 0.4 vs. 0.7 ± 0.7 mL/min, P < 0.001), and GFR (142.9 ± 17.9 vs. 58.0 ± 42.8 μL/min, P < 0.001). ConclusionThe multi-slice TRICKS-based DCE-MRI technique, with a semi-automated image processing scheme, allows rapid and comprehensive measurement of murine kidney function.

Rheumatoid cervical pannus: feasibility of volume and perfusion quantification using dynamic contrast enhanced time resolved MRI

Dynamic contrast-enhanced magnetic resonance imaging has the potential to show disease activity of rheumatoid arthritis even in complex anatomic areas as the atlantodental region. To demonstrate the technical feasibility of measuring synovial volume and perfusion characteristics with dynamic contrast-enhanced magnetic resonance imaging of the atlantodental region in patients with rheumatoid arthritis. Ten patients with rheumatoid arthritis and cervical spine involvement underwent dynamic contrast-enhanced magnetic resonance imaging of the cervical spine at 1.5 T. For each patient, 80 3D datasets were acquired using the commercialized Time Resolved Imaging of Contrast KineticS (TRICKS) sequence. Volumes of synovia with active synovitis on anatomical and parametric images were segmented. Synovial tissue perfusion parameters, namely plasma flow (Fp), relative plasma volume (vp), and the permeability-surface area product (PS), were calculated using a two-compartment uptake model. Statistical analysis included calculation of intra- and inter-reader agreement and a correlation of perfusion parameters with Outcome Measures in Rheumatology Clinical Trials (OMERACT) criteria. Dynamic contrast-enhanced magnetic resonance imaging as well as quantification of volume and perfusion characteristics of synovia was successful in most patients (80%). Intra- and inter-reader agreement was excellent (0.89-0.99). There was a positive correlation between OMERACT score and the permeability-surface product. Dynamic contrast-enhanced magnetic resonance imaging using a 4D angiography sequence for the atlantodental region in patients with rheumatoid arthritis for quantitative and qualitative assessment of synovial volume and perfusion characteristics is technically feasible.

Transient Global Amnesia Linked to Impairment of Brain Venous Drainage: An Ultrasound Investigation.

Background: Previous neuroimaging and ultrasound studies suggested that compression and stenosis of the internal jugular vein (IJV) in patients with transient global amnesia (TGA) may impair IJV drainage, while a patent IJV releases intracranial pressure caused by the Valsalva maneuver (VM).Methods: Seventy-nine TGA patients with complete ultrasound examination data during admission were recruited prospectively to evaluate IJV drainage, which included the time-averaged mean velocity, and the cross-sectional lumen area of the IJV at the vein's middle (J2) and distal (J3) segments and the cross-sectional area during a 10-s VM to test for any retrograde or anti-grade flow. Forty-five TGA patients and 45 age- and sex-matched control subjects underwent complete contrast-enhanced magnetic resonance (MR) venous studies, which included time-resolved imaging of contrast kinetics, contrast-enhanced axial T1-weighted MR imaging, and phase-contrast-based non-contrast enhanced magnetic resonance venography (MRV).Results: In those subjects with complete MRV studies, the flow volumes exhibited at both the J2 and J3 segments of the left IJV and left vertebral vein (VV) were significantly lower in the TGA patients than in the control subjects. Although there was no significant difference in the flow volume of right IJV, the total of bilateral IJV, and VV flow volumes was still significantly lower in the TGA patients. As compared with the control subjects, the TGA patients exhibited significantly higher prevalence of completely blocked right IJV drainage at the J3 segment during the VM, but non-significantly higher for the left IJV at the J3 segment and for the right IJV at the J2 segment.Conclusion: Our results confirmed that the total venous flow decreases in the IJVs and VVs of the patients with TGA. This is consistent with the findings of previous MR imaging studies that have reported about compression and stenosis of the draining veins. We also found that IJV drainage is relatively compromised during the VM in the patients with TGA.

Contrast-Enhanced Cerebral MR Venography Overcomes Causes of Drop of Signal in Time of Flight MR Venography

AbstractBackground: Cerebral venous thrombosis is uncommon disease with vague manifestations. Magnetic resonance venog-raphy (MRV) plays an important role in its diagnosis. The cardinal MRV sign of venous sinus thrombosis is sinus drop of signal. Using time of flight MR venography (TOF MRV) -the commonly used technique there are multiple causes of signal drop simulating dural sinus thrombosis.Aim of Study: To diagnose different causes of signal drop on TOF MRV using contrast enhanced MRV to avoid misin-terpretation of dural sinus thrombosis.Patients and Methods: 79 patients with clinical suspicion of cerebral venous sinus thrombosis underwent cerebral 2D-TOF and post-contrast MRV (time-resolved imaging of contrast kinetics (TRICKS) MRV in 40 patients & elliptic centric MRV in 39 patients). Findings in TOF MRV were compared to those in contrast-enhanced MRV.Results: Dural sinus thrombosis was seen in 30 cases. Turbulence of flow in superior sagittal sinus and lateral sinuses was demonstrated in 8 cases, hypoplastic transverse sinus was diagnosed in 23 cases, atretic transverse sinus was shown in 2 cases, stenosis of the transverse sinus was seen in 7 cases. 10 cases demonstrated normal dural sinuses on all used MRV techniques.Conclusion: Drop of signal in dural venous sinuses using TOF MRV has many causes other than thrombosis. To avoid misinterpretation it is important to use contrast enhanced MRV either TRICKS or elliptic centric techniques.

MRI evaluation of peripheral vascular anomalies using time-resolved imaging of contrast kinetics (TRICKS) sequence.

We describe the use of time-resolved imaging of contrast kinetics (TRICKS) sequence in the diagnosis of Peripheral Vascular Anomalies. In case of suspected vascular malformations time-resolved MR angiography might add important information for therapeutic decisions and follow-up. The objective of our study was to assess the usefulness and diagnostic performance of time-resolved imaging of contrast kinetics sequence in the evaluation of peripheral vascular anomalies. Sixty-six patients (23 pediatric, 43 adult; mean age 26) affected by upper or lower limb vascular anomalies and studied using time-resolved imaging of contrast kinetics sequence were prospectively evaluated. All studies were performed on a 1.5-T whole-body MR system. Two independent readers tried to categorized the suspected vascular anomalies in pre-contrast and post-contrast MR sequences and assessed the overall TRICKS image quality. In 11 patients, the diagnostic performance comparability between TRICKS sequence and digital subtraction angiography was evaluated. On the basis of time-resolved imaging of contrast kinetics, 31 of the vascular anomalies were classified as high-flow vascular malformations, 29 as low-flow vascular lesions and 6 as hemangiomas. There was no significant difference in image quality evaluation and vascular anomaly classification between the two observers. The vascular anomalies characteristics provided by moderate, good or excellent quality TRICKS images were confirmed by digital subtraction angiography. Time-resolved imaging of contrast kinetics sequence let the radiologist to acquire useful temporal information to correctly evaluate vascular anomalies components, adding more data to those provided by conventional MR sequences, especially in case of arteriovenous malformation. Therefore, both in pediatric and adult population, TRICKS could be used as an additional initial diagnostic tool to rightly classify these lesions and evaluate if a treatment is needed and which.

Comparative analysis of 3D time-resolved contrast-enhanced magnetic resonance angiography, color Doppler ultrasound and digital subtraction angiography in symptomatic carotid stenosis.

The present study aimed to compare the diagnostic value of contrast-enhanced magnetic resonance angiography (CE MRA) with 3D time-resolved imaging of contrast kinetics, color Doppler ultrasound (CDUS) and digital subtraction angiography (DSA) in extracranial carotid stenosis (CS). A total of 54 patients with symptomatic CS were subjected to CDUS, CE MRA and DSA examination. Results of DSA were defined as the standard, and a total of 216 vessels were examined. In each patient four vessels were examined, namely the bilateral common carotid arteries and the bilateral internal carotid arteries. The sensitivities and specificities of CE MRA and CDUS for various degrees of CS were also determined. It was observed that the sensitivities to mild-level (1-49%), moderate-level (50-69%) and severe-level (70-99%) CS were 85.45, 100 and 100% for CE MRA, and 78.18, 50 and 100% for CDUS, respectively. The corresponding specificities were 95.27, 98.58 and 99.53% for CE MRA, and 79.05, 93.36 and 98.10% for CDUS, respectively. In addition, the carotid sinus plaque detection rate for CDUS was significantly higher than that of DSA and CE MRA (both P<0.001). Detection rates for common carotid artery plaques and internal carotid artery plaques did not significantly differ among the three examination methods (all P>0.05). These data demonstrate that CE MRA has higher sensitivity and specificity than CDUS for the diagnosis of CS, and that CDUS has a higher carotid sinus plaque detection rate than DSA and CE MRA. Therefore, the combination of MRI and CDUS may be a 'gold standard' diagnostic method for the detection of moderate and severe CS.

Abbreviated breast magnetic resonance protocol: Value of high-resolution temporal dynamic sequence to improve lesion characterization

PurposeTo evaluate the added value of ULTRAFAST-MR sequence to an abbreviated FAST protocol in comparison with FULL protocol to distinguish benign from malignant lesions in a population of women, regardless of breast MR imaging indication. Materials and methodsFrom March 10th to September 22th, 2014, we retrospectively included a total of 70 consecutive patients with 106 histologically proven lesions (58 malignant and 48 benign) who underwent breast MR imaging for preoperative breast staging (n=38), high-risk screening (n=7), problem solving (n=18), and nipple discharge (n=4) with 12 time resolved imaging of contrast kinetics (TRICKS) acquisitions during contrast inflow interleaved in a regular high-resolution dynamic MRI protocol (FULL protocol). Two readers scored MR exams as either positive or negative and described significant lesions according to Bi-RADS lexicon with a TRICKS images (ULTRAFAST), an abbreviated protocol (FAST) and all images (FULL protocol). Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for each protocol and compared with McNemar’s test. ResultsFor all readers, the combined FAST–ULTRAFAST protocol significantly improved the reading with a specificity of 83.3% and 70.8% in comparison with FAST protocol or FULL protocol, respectively, without change in sensitivity. By adding ULTRAFAST protocol to FAST protocol, readers 1 and 2 were able to correctly change the diagnosis in 22.9% (11/48) and 10.4% (5/48) of benign lesions, without missing any malignancy, respectively. Both interpretation and image acquisition times for combined FAST-ULTRAFAST protocol and FAST protocol were shorter compared to FULL protocol (p<0.001). ConclusionCompared to FULL protocol, adding ULTRAFAST to FAST protocol improves specificity, mainly in correctly reclassifying benign masses and reducing interpretation and acquisition time, without decreasing sensitivity.

Dynamic contrast-enhanced MRI of the patellar bone: How to quantify perfusion.

PurposeTo identify the optimal combination of pharmacokinetic model and arterial input function (AIF) for quantitative analysis of blood perfusion in the patellar bone using dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI).Materials and MethodsThis method design study used a random subset of five control subjects from an Institutional Review Board (IRB)‐approved case–control study into patellofemoral pain, scanned on a 3T MR system with a contrast‐enhanced time‐resolved imaging of contrast kinetics (TRICKS) sequence. We systematically investigated the reproducibility of pharmacokinetic parameters for all combinations of Orton and Parker AIF models with Tofts, Extended Tofts (ETofts), and Brix pharmacokinetic models. Furthermore, we evaluated if the AIF should use literature parameters, be subject‐specific, or group‐specific. Model selection was based on the goodness‐of‐fit and the coefficient of variation of the pharmacokinetic parameters inside the patella. This extends previous studies that were not focused on the patella and did not evaluate as many combinations of arterial and pharmacokinetic models.ResultsThe vascular component in the ETofts model could not reliably be recovered (coefficient of variation [CV] of vp >50%) and the Brix model parameters showed high variability of up to 20% for kel across good AIF models. Compared to group‐specific AIF, the subject‐specific AIF's mostly had higher residual. The best reproducibility and goodness‐of‐fit were obtained by combining Tofts' pharmacokinetic model with the group‐specific Parker AIF.ConclusionWe identified several good combinations of pharmacokinetic models and AIF for quantitative analysis of perfusion in the patellar bone. The recommended combination is Tofts pharmacokinetic model combined with a group‐specific Parker AIF model. Level of Evidence: 2 Technical Efficacy: Stage 1J. Magn. Reson. Imaging 2018;47:848–858.

Assessment and treatment planning of lateral intracranial dural arteriovenous fistulas in 3T MRI and DSA: A detailed analysis under consideration of time-resolved imaging of contrast kinetics (TRICKS) and ce-MRA sequences.

The current gold standard in the assessment of lateral intracranial dural arteriovenous fistulas (LDAVF) is digital subtraction angiography (DSA). However, magnetic resonance imaging (MRI) is a non-invasive emerging tool for the evaluation of such lesions. The aim of our study was to compare the DSA to our 3T MR-imaging protocol including a highly spatial resolved (ce-MRA) and a temporal resolved ("time-resolved imaging of contrast kinetics", TRICKS) contrast-enhanced MR angiography to evaluate if solely DSA can remain the gold-standard imaging modality for the treatment planning of LDAVF. We retrospectively reviewed matched pairs of DSA and 3T MRI examinations of 24 patients with LDAVF (03/2008-04/2014) by the same list of relevant criteria for an endovascular LDAVF treatment planning. In particular, we determined intermodality agreement for the Cognard classification, the identifeication of arterial feeders, and the detailed assessment of each venous drainage pattern. Intermodality agreement for the Cognard classification was excellent (ĸ = 1.0). Whereas MRI failed in identifying small arterial feeders, it was superior to the DSA in the assessment of the sinus and the venous drainage pattern. The combination of MRI and DSA is the new gold standard in LDAVF treatment planning. • DSA is superior to the MRI in detecting LDAVF arterial feeders. • MRI excellently evaluates the venous side of an LDAVF. • MRI can replace DSA in initial diagnosis and monitoring of LDAVF. • MRI and DSA combined are the new gold standard in LDAVF treatment planning.

Optimized time-resolved imaging of contrast kinetics (TRICKS) in dynamic contrast-enhanced MRI after peptide receptor radionuclide therapy in small animal tumor models.

Anti-tumor efficacy of targeted peptide-receptor radionuclide therapy (PRRT) relies on several factors, including functional tumor vasculature. Little is known about the effect of PRRT on tumor vasculature. With dynamic contrast-enhanced (DCE-) MRI, functional vasculature is imaged and quantified using contrast agents. In small animals DCE-MRI is a challenging application. We optimized a clinical sequence for fast hemodynamic acquisitions, time-resolved imaging of contrast kinetics (TRICKS), to obtain DCE-MRI images at both high spatial and high temporal resolution in mice and rats. Using TRICKS, functional vasculature was measured prior to PRRT and longitudinally to investigate the effect of treatment on tumor vascular characteristics. Nude mice bearing H69 tumor xenografts and rats bearing syngeneic CA20948 tumors were used to study perfusion following PRRT administration with (177) lutetium octreotate. Both semi-quantitative and quantitative parameters were calculated. Treatment efficacy was measured by tumor-size reduction. Optimized TRICKS enabled MRI at 0.032 mm(3) voxel size with a temporal resolution of less than 5 s and large volume coverage, a substantial improvement over routine pre-clinical DCE-MRI studies. Tumor response to therapy was reflected in changes in tumor perfusion/permeability parameters. The H69 tumor model showed pronounced changes in DCE-derived parameters following PRRT. The rat CA20948 tumor model showed more heterogeneity in both treatment outcome and perfusion parameters. TRICKS enabled the acquisition of DCE-MRI at both high temporal resolution (Tres ) and spatial resolutions relevant for small animal tumor models. With the high Tres enabled by TRICKS, accurate pharmacokinetic data modeling was feasible. DCE-MRI parameters revealed changes over time and showed a clear relationship between tumor size and Ktrans .

The role of time-resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography (MRA) in the evaluation of head-neck vascular anomalies: a preliminary experience.

In this preliminary report, we describe our experience with time-resolved imaging of contrast kinetics-MR angiography (TRICKS-MRA) in the assessment of head-neck vascular anomalies (HNVAs). We prospectively studied six consecutive patients with clinically suspected or diagnosed HNVAs. All of them underwent TRICKS-MRA of the head and neck as part of the routine for treatment planning. A digital subtraction angiography (DSA) was also performed. TRICKS-MRA could be achieved in all cases. Three subjects were treated based on TRICKS-MRA imaging findings and subsequent DSA examination. In all of them, DSA confirmed the vascular architecture of HNVAs shown by TRICKS-MRA. In the other three patients, a close follow up to assess the evolution of the suspected haemangioma was preferred. TRICKS sequences add important diagnostic information in cases of HNVAs, helpful for therapeutic decisions and post-treatment follow up. We recommend TRICKS-MRA use (if technically possible) as part of routine MRI protocol for HNVAs, representing a possible alternative imaging tool to conventional DSA.

Time-resolved contrast-enhanced MR angiography of spinal vascular malformations.

The diagnosis of spinal vascular malformations may be challenging on conventional MR imaging because neither the location of the signal abnormality in the spinal cord nor the level of the abnormal flow voids correlates with the level of the fistula. We conducted a retrospective evaluation of the utility of using a time-resolved imaging of contrast kinetics sequence in the diagnosis, characterization, and localization of spinal vascular malformations, comparing it with the criterion standard of spinal DSA. Fifty-five consecutive patients with a suspected diagnosis of spinal vascular malformation underwent time-resolved imaging of contrast kinetics followed by spinal DSA. All scans were performed on a 1.5T scanner by using a standard 8-channel spine coil and were reported by a neuroradiologist before the DSA was performed. Forty-seven lesions were confirmed on time-resolved imaging of contrast kinetics and classified as spinal dural arteriovenous fistulas (n = 33, with 1 patient having a type Ib fistula), perimedullary spinal cord arteriovenous fistulas (n = 10), and intramedullary arteriovenous malformations (n = 3). One patient had an extradural spinal vascular malformation. Time-resolved imaging of contrast kinetics identified the location of the arterial feeder to within 1 vertebral level in 27/33 patients (81.8%) with spinal dural arteriovenous fistulas and correctly predicted the side in 22/33 (66.6%) patients. Perimedullary spinal cord arteriovenous fistulas were erroneously considered to represent spinal dural arteriovenous fistulas before spinal DSA. The anatomy of the arterial supply to intramedullary arteriovenous malformations was also poorly characterized on time-resolved contrast-enhanced MR angiography. It has been our experience that time-resolved imaging of contrast kinetics is a useful confirmatory tool when a spinal vascular malformation is suspected on the basis of clinical and conventional MR imaging findings. As experience with the technique grows and sequences are refined, it may be possible to rely on time-resolved imaging of contrast kinetics as a screening tool for the diagnosis of spinal vascular malformations.

Contrast-enhanced time-resolved MRA for follow-up of intracranial aneurysms treated with the pipeline embolization device.

Endovascular reconstruction and flow diversion by using the Pipeline Embolization Device is an effective treatment for complex cerebral aneurysms. Accurate noninvasive alternatives to DSA for follow-up after Pipeline Embolization Device treatment are desirable. This study evaluated the accuracy of contrast-enhanced time-resolved MRA for this purpose, hypothesizing that contrast-enhanced time-resolved MRA will be comparable with DSA and superior to 3D-TOF MRA. During a 24-month period, 37 Pipeline Embolization Device-treated intracranial aneurysms in 26 patients underwent initial follow-up by using 3D-TOF MRA, contrast-enhanced time-resolved MRA, and DSA. MRA was performed on a 1.5T unit by using 3D-TOF and time-resolved imaging of contrast kinetics. All patients underwent DSA a median of 0 days (range, 0-68) after MRA. Studies were evaluated for aneurysm occlusion, quality of visualization of the reconstructed artery, and measurable luminal diameter of the Pipeline Embolization Device, with DSA used as the reference standard. The sensitivity, specificity, and positive and negative predictive values of contrast-enhanced time-resolved MRA relative to DSA for posttreatment aneurysm occlusion were 96%, 85%, 92%, and 92%. Contrast-enhanced time-resolved MRA demonstrated superior quality of visualization (P = .0001) and a higher measurable luminal diameter (P = .0001) of the reconstructed artery compared with 3D-TOF MRA but no significant difference compared with DSA. Contrast-enhanced time-resolved MRA underestimated the luminal diameter of the reconstructed artery by 0.965 ± 0.497 mm (27% ± 13%) relative to DSA. Contrast-enhanced time-resolved MRA is a reliable noninvasive method for monitoring intracranial aneurysms following flow diversion and vessel reconstruction by using the Pipeline Embolization Device.

Contrast-enhanced time-resolved MRA for pre-angiographic evaluation of suspected spinal dural arterial venous fistulas

BackgroundSpinal digital subtraction angiography (DSA) is the gold standard for diagnosis of spinal dural arterial venous fistulas (SDAVFs), but can require extensive time, radiation exposure and contrast dose. We hypothesize...

Time resolved imaging of contrast kinetics (TRICKS) MR angiography of arteriovenous malformations of head and neck

PurposeTo evaluate vasculature of arteriovenous malformations (AVMs) of head and neck with time resolved imaging of contrast kinetics (TRICKS) MR angiography (MRA). Material and methodsProspective study was conducted upon 19 patients (age range, 12–29 years; mean age 18 years; 10 males and 9 females) with AVM of head and neck. TRICKS-MRA of head and neck was performed during injection of contrast medium. Post processing with reconstruction of the images was done. Two independent readers assessed the overall TRICKS-MRA image quality score using a 5-point scale and depiction of the main arterial feeders, nidus, and venous drainage using 3 points scale. The Kappa test for interobserver agreement was done. The AVMs were evaluated morphologically in terms of number and origin of the main arterial feeders, the location and size of nidus either small (>2cm) or large (>2cm) and the draining veins into the superficial or deep venous drainage. ResultsThe average TRICKS-MRA image quality score as judged by reader 1 was 3.89±1.15 and that as judged by reader 2 was 3.89±0.10, which yielded excellent interobserver agreement (k=0.77, 95% CI=0.53–0.98, r=0.78, P=0.001). The interobserver agreement of both readers was excellent for the arterial feeders (k=0.81, 95% CI=0.57–1.00, r=0.83, P=0.001), excellent for the nidus (k=0.91, 95% CI=0.75–1.00, r=0.92, P=0.001), and good for the venous drainage (k=0.77, 95% CI=0.53–0.98, r=0.78, P=0.001). The arterial feeders were single (n=14) or multiple (n=5), the nidus was large (n=16) or small (n=3) and the venous drainage was into the internal jugular (n=17) or the external jugular (n=2) veins. Three patients with small nidus and single arterial feeder were treated with sclerotherapy. Eleven patients with large nidus and single arterial feeder were referred for embolization. Combined embolization and surgery were done for five patients with large nidus and multiple arterial feeders. ConclusionWe concluded that TRICKS-MRA is a reliable non invasive tool for evaluation of the feeding arteries, the nidus and the draining veins of AVMs of head and neck. TRICKS-MRA can be used for evaluation and treatment planning of AVMs of head and neck.