Paget's Disease or Densifying Metastasis: How to Sort It Out.

Although the prevalence of Paget's disease has decreased over the past 20 years, incidental discovery on imaging is not unusual. The challenge is to establish the diagnosis, especially in unusual forms that may be mistaken for metastases. This review describes the typical imaging features of Paget's disease and some rare presentations that may be more difficult to recognize.

Hindfoot alignment assessment by the foot-ankle offset: a diagnostic study.

INTRODUCTION: Foot-ankle offset (FAO) is a three-dimensional (3D) biometric measurement of hindfoot alignment (HA) measured on images from weight-bearing computed tomography (WBCT). Our aim was to investigate its distribution in a large cohort of patients, hypothesizing that threshold FAO values in valgus or varus could be identified as markers for increased risk of associated pathologies. MATERIALS AND METHODS: Prospective, monocentric, level II study including 125 subjects (250 feet) undergoing bilateral WBCT [58.4% female; mean age, 54 years (18-84)]. Patients were clinically assessed and pathologies were classified according to anatomic location (valgus- or varus associated). HA was measured using FAO on 3D datasets and tibio-calcaneal angles (TCA) on two-dimensional Saltzman-El-Khoury views. Threshold FAO values and area under the receiver operating characteristics curve (AUC) were calculated for predicting increased risk of medial or lateral pathologies. RESULTS: Mean FAO was 1.65% ± 4.72 and mean TCA was 4.15° ± 7.67. Clinically, 167 feet were normal, 33 varus and 50 valgus with FAO values of 1.71% ± 3.16, - 4.96% ± 5.30 and 5.79% ± 3.77, respectively. Mean FAO was 0.99% ± 3.26 for non-pathological feet, - 2.53% ± 5.05 for lateral and 6.81% ± 2.70 for medial pathologies. Threshold FAO values of - 1.64% (51.4% sensitivity, 85.1% specificity, AUC = 0.72) and 2.71% (95% sensitivity, 82.8% specificity, AUC = 0.93) best predicted the risk of lateral and medial pathology, respectively. CONCLUSION: Patients with FAO between - 1.64% and 2.71% had the least risk of degenerative foot and ankle pathology. This interval could be considered a target for patients undergoing realignment procedures. CLINICAL RELEVANCE: A "safe zone" for Foot Ankle Offset was described between - 1.64% and 2.71%, for which the risk of foot and ankle pathologies is lower. LEVEL OF EVIDENCE: II-Diagnostic study.

The concept of ring of injuries: evaluation in ankle trauma.

OBJECTIVE: Radiographs are first-line imaging in ankle trauma but lack sensitivity to detect ligamentous injuries and undisplaced fractures. Our hypothesis was that ankle injuries occur in predefined sequences along two osteoligamentous rings, so that occult injuries non-visible on initial radiographs can be predicted. We, therefore, aimed to validate a ring model of progressive damages in the interpretation of ankle trauma radiographs. METHODS: This study retrospectively enrolled 277 adult patients that presented an acute fibular fracture on ankle radiographs between May and November 2019. Four different types of fibula fracture were differentiated, each being considered to correspond to a different mechanism of injury. Patients were classified into four groups, upon the appearance of their fibular fracture. Then, injuries to the distal tibiofibular syndesmosis, medial malleolus, and deltoid ligament (medial clear space) were assessed in each patient radiographs. Traumatic injuries were independently evaluated by a resident and an experienced MSK radiologist. For each patient, observed features were compared to those predicted by the ring concept. Inter- and intraobserver agreements were calculated. RESULTS: Injuries were observed according to the predictable sequence in 266 of the 277 patients (96%). In the 11 remaining patients, discordances were presumably due to undisplaced injuries to the syndesmosis or deltoid ligament. Agreements were considered very good for each evaluated item. CONCLUSION: The Lauge-Hansen ring concept was found to be highly accurate and reproducible for radiographic assessment of ankle injuries. Discordances to the predicted sequence might reflect occult injuries, especially of the syndesmosis or deltoid ligament.

How to improve the performance of acetabulum fracture diagnoses: investigating the use of three-dimensional CT-scan reconstructions.

PURPOSE: The classification of acetabular fractures remains a challenge for the junior radiologist, although he is the first line of diagnosis in Emergency Department. The advantages of three-dimensional reconstructions have yet to be evaluated on a large scale. METHOD: A total of 212 fractures were classified according to Letournel and Judet by a senior orthopaedic surgeon, a senior radiologist, and a resident radiologist. The CT scans were first analysed in 2D and then a second time using 2D + 3D reconstructions of the acetabulum excluding the femoral head. RESULTS: 3D reconstructions improved correct classification not only for the radiologist resident (+ 5%) but also for senior radiologist and orthopaedist (+ 2 and + 3%). 3D reconstructions also more significantly improved the diagnoses of complex fractures (+ 8.3%) compared to simple fractures (+ 0.4%). CONCLUSIONS: 3D reconstructions have improved the routine diagnosis of acetabular fractures, especially for junior radiologist or in cases of complex fractures.

MRI of sacroiliac joints for the diagnosis of axial SpA: prevalence of inflammatory and structural lesions in nulliparous, early postpartum and late postpartum women.

OBJECTIVES: To determine the prevalence of bone marrow oedema (BME) at the sacroiliac joint (SIJ) in early postpartum (EPP), nulliparous (NP) and late postpartum (LPP) women, and to identify factors associated with BME presence at the SIJ. METHODS: Three groups were obtained: NP (never given birth), EPP (given birth within 12 months) and LPP (given birth more than 24 months). The primary outcome was the presence of BME and/or structural lesions (erosions, osteophytes, ankylosis and sclerosis) at the SIJ MRI. RESULTS: BME prevalence was greater among EPP (33%) than NP (14%, p=0.001), but was not different to LPP (21%, p=0.071). The Assessment of SpondyloArthritis international Society (ASAS) MRI criteria for sacroiliitis were positive in 75%, 71% and 80%, respectively, of EPP, NP and LPP women with BME. EPP (38%) had similar prevalence of sclerosis than LPP (28%, p=0.135), but greater than NP (18%, p=0.001). Lastly, EPP (28%) had similar prevalence of osteophytes than LPP (42%) and NP (27%), although there was a difference between LPP and NP (p=0.006). CONCLUSIONS: EPP have higher BME prevalence at the SIJ than NP, EPP tend to have higher BME prevalence compared with LPP and BME presence decreases with time from delivery. Three-quarters of women with BME at the SIJ had a positive ASAS MRI criteria for sacroiliitis, indicating that BME presence as the main criterion for a positive diagnosis can lead to false-positive results. SIJ MRIs should not be interpreted in isolation, since age, time from delivery and other factors may outweigh the pertinence of MRI findings. Trial registration number NCT02956824.

Bifascicular nature of the flexor digitorum profundus and flexor pollicis longus tendons: forgotten anatomical characteristics rediscovered with US imaging.

OBJECTIVES: To demonstrate the bifid configuration of the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL). METHODS: In the first part of this study, 20 digits from 4 cadaver hands were dissected and analyzed using anatomical and histological slices. The second part of the study was carried out over a 12-month period starting in August 2018. It was a prospective US imaging study of 300 digits from 30 healthy participants performed by two radiologists in a double-blinded manner. This study focused on two items: tendon shape and whether a central septum separated the two hemitendons. Descriptive statistics were calculated along with the inter-rater reliability. RESULTS: In 100% (300/300) of fingers and thumbs, the FDP and FPL tendons were made up of two parallel bundles arranged side by side, with a central vertical septum between these two hemitendons, starting at the head of the proximal phalanx (PP) and continuing distally. This central septum was always present starting at the proximal third of PP for the FDP of the index, middle, and ring fingers. The septum was more difficult to identify in the thumb and little finger. Cohen's kappa indicated near perfect agreement when all digits were considered together (≥ 0.9), and substantial agreement for the thumb (0.71) and for the little finger (0.82). CONCLUSIONS: With US imaging, the bifascicular nature of the FDP and FPL tendons is easy to see, as these tendons have a double-barreled configuration starting at the head of the proximal phalanx. KEY POINTS: •Analysis of anatomical slices of the hand tendons found a bifascicular appearance of the flexor digitorum profundus and flexor pollicis longus tendons starting at the head of the proximal phalanx. •This distinct feature of two hemitendons arranged side by side was seen in 100% of tendons we examined with US. It is associated with a vertical central septum that causes anisotropy. •Awareness of this "forgotten" anatomical detail has practical implications when interpreting images generated by latest-generation US systems and during surgery on hand flexor tendons.

COVID-19 impact assessment on the French radiological centers: a nationwide survey.

PURPOSE: To determine the impact of the COVID-19 on the CT activities in French radiological centers during the epidemic peak. MATERIALS AND METHODS: A cross-sectional prospective CT scan survey was conducted between March 16 and April 12, 2020, in accordance with the local IRB. Seven hundred nine radiology centers were invited to participate in a weekly online survey. Numbers of CT examinations related to COVID-19 including at least chest (CTcovid) and whole chest CT scan activities (CTchest) were recorded each week. A sub-analysis on French departments was performed during the 4 weeks of the study. The impact of the number of RT-PCRs (reverse transcriptase polymerase chain reactions) on the CT workflow was tested using two-sample t test and Pearson's test. RESULTS: Five hundred seventy-seven structures finally registered (78%) with mean response numbers of 336 ± 18.9 (323; 351). Mean CTchest activity per radiologic structure ranged from 75.8 ± 133 (0-1444) on week 12 to 99.3 ± 138.6 (0-1147) on week 13. Mean ratio of CTcovid on CTchest varied from 0.36 to 0.59 on week 12 and week 14 respectively. There was a significant relationship between the number of RT-PCR performed and the number of CTcovid (r = 0.73, p = 3.10-16) but no link with the number of positive RT-PCR results. CONCLUSION: In case of local high density COVID-19, CT workflow is strongly modified and redirected to the management of these specific patients. KEY POINTS: • Over the 4-week survey period, 117,686 chest CT (CTtotal) were performed among the responding centers, including 61,784 (52%) CT performed for COVID-19 (CTcovid). • Across the country, the ratio CTcovid/CTtotal varied from 0.36 to 0.59 and depended significantly on the local epidemic density (p = 0.003). • In clinical practice, in a context of growing epidemic, in France, chest CT was used as a surrogate to RT-PCR for patient triage.

National dose reference levels in computed tomography-guided interventional procedures-a proposal.

OBJECTIVES: To establish national reference levels (RLs) in interventional procedures under CT guidance as required by the 2013/59/Euratom European Directive. METHODS: Seventeen categories of interventional procedures in thoracic, abdominopelvic, and osteoarticular specialties (percutaneous infiltration, vertebroplasty, biopsy, drainage, tumor destruction) were analyzed. Total dose length product (DLP), number of helical acquisitions (NH), and total DLP for helical, sequential, or fluoroscopic acquisitions were recorded for 10 to 20 patients per procedure at each center. RLs were calculated as the 3rd quartiles of the distributions and target values for optimization process (TVOs) as the median. RLs and TVOs were compared with previously published studies. RESULTS: Results on 5001 procedures from 49 centers confirmed the great variability in patient dose for the same category of procedures. RLs were proposed for the DLPs and NHs in the seventeen categories. RLs in terms of DLP and NH were 375 mGy.cm and 2 NH for spinal or peri-spinal infiltration, 1630 mGy.cm and 3 NH for vertebroplasty, 845 mGy.cm and 4 NH for biopsy, 1950 mGy.cm and 8 NH for destruction of tumors, and 1090 mGy.cm and 5 NH for drainage. DLP and NH increased with the complexity of procedures. CONCLUSIONS: This study was the first nationwide multicentric survey to propose RLs for interventional procedures under CT guidance. Heterogeneity of practice in centers were found with different levels of patient doses for the same procedure. The proposed RLs will allow imaging departments to benchmark their practice with others and optimize their protocols. KEY POINTS: • National reference levels are proposed for 17 categories of interventional procedures under CT guidance. • Reference levels are useful for benchmarking practices and optimizing protocols. • Reference levels are proposed for dose length product and the number of helical acquisitions.

Correction to: National dose reference levels in computed tomography-guided interventional procedures-a proposal.

The original version of this article, published on 02 May 2020, unfortunately contained a mistake.

Case 264: A Case of Osseous Sarcoidosis.

History A 28-year-old woman presented to the emergency department with painful swelling of the third finger on her right hand, which developed quickly. She had no relevant medical or surgical history. Her pain was worse at night, with stiffness decreasing during the morning. Clinical examination revealed generalized swelling of the third finger, cyanotic skin, and fingernail splitting on the second finger of the left hand ( Fig 1 ). Laboratory test results were normal, with no evidence of inflammatory disease. Radiographs of both hands were obtained. CT scanning and MRI were also performed. Figure 1: Photograph of both of the patient's hands shows generalized swelling of the third digit of the right hand, corresponding to dactylitis (arrow). Also note the nail striations in the second digit of the left hand (∗).

Prevalence of inflammatory posterior arch abnormalities on lumbar spine MRI in spondyloarthritis patients compared with low back pain patients.

OBJECTIVES: This study was conducted in order to compare the prevalence of inflammatory posterior arch abnormalities on lumbar spine MRI between axial spondyloarthritis (axSpA) patients and low back pain (LBP) patients. METHODS: Patients-axSpA patients meeting the 2009 ASAS criteria and chronic LBP patients who had a lumbar spine MRI were selected. MRI-STIR and T1 sagittal images up to T8-T9 were reviewed by two experienced rheumatologists blinded to the diagnosis and clinical data to identify inflammatory posterior arch abnormalities. Analyses-The prevalence of inflammatory posterior arch abnormalities between axSpA and LBP patients was compared. Clinical data were compared in the axSpA group depending on whether or not inflammatory posterior arch abnormalities were present. RESULTS: Ninety-five patients were enrolled in each group. The prevalence of all inflammatory posterior arch abnormalities was the same in the axSpA and LBP groups (58% in the SpA group versus 70% in the LBP group, p = 0.1). However, differences in terms of the prevalence of costotransverse joint arthritis, pedicle oedema above L3 and transverse and spinous process oedema were observed between the two groups (axSpA 27% versus LBP 6%, p = 0.0004). Patients with inflammatory posterior arch abnormalities in the axSpA group had a longer disease duration (11 versus 8 years, p = 0.02), higher CRP levels (median 11 versus 3 mg/l, p = 0.0002) and higher prevalence of radiographic sacroiliitis (84 versus 47%, p = 0.001) compared to patients without inflammatory posterior arch abnormalities. CONCLUSIONS: Costotransverse arthritis, pedicle oedema and transverse process oedema are more frequent in axSpA patients than LBP patients, on lumbar spine MRI depicting TH9-S1. KEY POINTS: • MRI pedicle oedema above L3, transverse process oedema, spinous process oedema or costotransverse arthritis is more frequently observed in axial spondyloarthritis (SpA). • SpA patients with at least one MRI inflammatory lesion on the posterior arch had higher clinical activity scores and biological inflammation. • Facet joint arthritis was more common in patients with chronic low back pain.

Case 264.

History A 28-year-old woman presented to the emergency department with painful swelling of the third finger on her right hand, which developed quickly. She had no relevant medical or surgical history. Her pain was worse at night, with stiffness decreasing during the morning. Clinical examination revealed generalized swelling of the third finger, cyanotic skin, and fingernail splitting on the second finger of the left hand ( Fig 1 ). Laboratory test results were normal, with no evidence of inflammatory disease. Radiographs of both hands were obtained ( Fig 2 ). CT scanning ( Fig 3 ) and MRI ( Fig 4 ) were also performed. [Figure: see text] [Figure: see text] [Figure: see text] [Figure: see text] [Figure: see text] [Figure: see text] [Figure: see text] [Figure: see text].

Anterolateral ligament injuries in knees with an anterior cruciate ligament tear: Contribution of ultrasonography and MRI.

OBJECTIVES: To describe the pathological appearance of the anterolateral ligament (ALL) on US and MRI in knees with an anterior cruciate ligament (ACL) tear. METHODS: This prospective study included 30 patients who had a suspected acute ACL tear. Their injured and contralateral knees were evaluated with radiography, US and MRI. Two radiologists evaluated the ALL on the MRI and US examinations. Agreement between these examiners' findings was evaluated with Cohen's kappa. RESULTS: On US examination, the ALL was found to be injured in 63% of cases (19/30; k = 0.93). The enthesis was found to be torn in 50% of cases (15/30; k = 1), with the tear located at the tibial attachment in all instances. On the MRI exam, the ALL was found to be injured in 53% of cases (16/30; k = 0.93). The enthesis was found to be torn in 13% of cases (4/30; k = 0.76), with the tear located at the tibial attachment in all instances (k = 0.93). CONCLUSION: ALL injuries that occur with ACL tears are located at the tibial enthesis. They are often associated with bone avulsion at the enthesis and are better viewed on US. KEY POINTS: • ALL injuries often occur in combination with ACL tears. • ALL injuries can be assessed with ultrasonography and MRI. • ALL injuries associated with ACL tears are located at the tibial enthesis.

US-guided percutaneous release of the first extensor tendon compartment using a 21-gauge needle in de Quervain's disease: a prospective study of 35 cases.

PURPOSE: To evaluate the efficacy of ultrasonography-guided percutaneous treatment of de Quervain tenosynovitis with the combination of a corticosteroid injection and release of the retinaculum of the first extensor compartment tendons with a 21-gauge needle. MATERIALS AND METHODS: The first part of our study consisted of ten procedures on cadaver wrists followed by dissection to analyse the effectiveness of the retinaculum release and detect any collateral damage. The second part was a prospective clinical study of 35 procedures. Outcomes were evaluated through a 6-month clinical follow-up and telephone interview at the end of the study. The following parameters were monitored over time: pain level on a visual analogue scale, the QuickDASH and the PRWE. Patient satisfaction questionnaires were also administered. RESULTS: No complications were found during the cadaver study. However, the release was confirmed as 'partial' in all wrists. In the clinical portion of this study, significant improvement was observed in 91.4 % of cases (32/35) within 1 month and the results were stable until the end of the study; all of these patients avoided surgery. The release procedure failed in three patients who eventually required surgical treatment. CONCLUSION: US-guided partial release and simultaneous corticosteroid injection for treatment of de Quervain's disease using a 21-gauge needle is feasible in current practice, with minimal complications. KEY POINTS: • Ultrasound-guided treatment of de Quervain's disease is feasible with a 21G needle. • There was notable regression of clinical signs in 91.4 % of cases. • The procedure is very safe, no iatrogenic neurovascular or tendinous injuries occurred. • Our procedure requires only one session and 3 days away from work.

Ultrasound of the coracoclavicular ligaments in the acute phase of an acromioclavicular disjonction: Comparison of radiographic, ultrasound and MRI findings.

OBJECTIVES: Acromioclavicular joint injuries are typically diagnosed by clinical and radiographic assessment with the Rockwood classification, which is crucial for treatment planning. The purpose of this study was to describe how the ultrasound findings of acromioclavicular joint injury compare with radiography and MRI findings. METHODS: Forty-seven patients with suspected unilateral acromioclavicular joint injury after acute trauma were enrolled in this prospective study. All patients underwent digital radiography, ultrasound and 3T MRI. A modified Rockwood classification was used to evaluate the coracoclavicular ligaments. The classifications of acromioclavicular joint injuries diagnosed with radiography, ultrasound and MRI were compared. MRI was used as the gold standard. RESULTS: The agreement between the ultrasound and MRI findings was very good, with a correlation coefficient of 0.83 (95 % CI: 0.72-0.90; p < 0.0001). Ultrasound detected coracoclavicular ligament injuries with a sensitivity of 88.9 %, specificity of 90.0 %, positive predictive value of 92.3 % and negative predictive value of 85.7 %. The agreement between the ultrasound and radiography findings was poor, with a correlation coefficient of 0.69 (95 % CI: 0.51-0.82; p < 0.0001). CONCLUSION: Ultrasound is an effective examination for the diagnostic work-up of lesions of the coracoclavicular ligaments in the acute phase of an acromioclavicular injury. KEY POINTS: • Ultrasound is appropriate for acute acromioclavicular trauma due to its accessibility. • Ultrasound contributes to the diagnostic work-up of acute lesions of the coracoclavicular ligaments. • Ultrasound is appropriate in patients likely to benefit from surgical treatment. • Ultrasound could be a supplement to standard radiography in acute acromioclavicular trauma.

Bone age estimation based on multislice computed tomography study of the scapula.

Progress in medical imaging has opened new areas of research in forensic anthropology, especially in the context of the study of bone age assessment. The study of bone age has become a useful tool for age estimation at death or age of young adult migrants in an anthropological context. We retrospectively evaluated multislice computed tomography (MSCT) explorations focused on scapulae of 232 individuals (123 males; 109 females) aged between 8 and 30 years old. Computed tomography (CT) scans were viewed in axial and multiplanar reconstructed images using OsiriX 5.9 (64 bit)®. The ossification centers of the scapula studied were as follows: acromial, sub-coracoid, glenoid, coracoid, coracoid apex, and inferior angle epiphyses. Fusion status was scored based on a five-stage system (stage 1: no ossification, stage 2: visualization of an ossification center, stage 3: partial ossification, stage 4: full ossification associated to an epiphyseal scar, and stage 5: full ossification without epiphyseal scar). Intra-observer variability was excellent, and inter-observer variability was good, demonstrating the reliability of this MSCT staging system. The fusion of scapular ossification centers was statistically associated with age (p < 0.001) but not with sex (p > 0.05). In conclusion, MSCT of the scapula is an efficient method for age assessment, which is complementary to preexisting methods particularly for specifying the 18-year threshold. Further studies with larger groups are needed to support our results.

US-guided Percutaneous Release of the Trigger Finger by Using a 21-gauge Needle: A Prospective Study of 60 Cases.

Purpose To evaluate the efficacy of ultrasonographically (US)-guided percutaneous treatment of the trigger finger by releasing the A1 pulley with a 21-gauge needle. Materials and Methods This two-part study was approved by the ethics committee, and written consent was obtained from all patients. The first part consisted of 10 procedures on cadaver digits followed by dissection to analyze the effectiveness of the A1 pulley release and detect any collateral damage to the A2 pulley, interdigital nerves, or underlying flexor tendons. The second part was performed during an 18-month period starting in March 2013. It was a prospective clinical study of 60 procedures performed in 48 patients. Outcomes were evaluated through a clinical examination at day 0 and during a 6-month follow-up visit, where the trigger digit was evaluated clinically and the Quick Disabilities of the Arm, Shoulder and Hand outcome measure, or QuickDASH, and patient satisfaction questionnaires were administered. Results No complications were found during the cadaver study. However, the release was considered "partial" in all fingers. In the clinical study, the trigger finger was completely resolved in 81.7% (49 of 60) of cases immediately after the procedure. Moderate trigger finger persisted in 10 cases, and one thumb pulley could not be released. A US-guided corticosteroid injection was subsequently performed in these 11 cases. At 6-month follow-up, only two cases still had moderate trigger finger and there were no late complications. The mean QuickDASH questionnaire score was 4; all patients said they were satisfied. Conclusion US-guided treatment of the trigger finger by using a 21-gauge needle is feasible in current practice, with minimal complications. (©) RSNA, 2016 Online supplemental material is available for this article.

Non-contrast-enhanced MR angiography using time-spin labelling inversion pulse technique for detecting crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with surgical findings.

OBJECTIVES: Investigate the feasibility and evaluate the accuracy of non-contrast-enhanced MR angiography (NC-MRA) using time-spin labelling inversion pulse (time-SLIP)to identify crossing renal vessels (CRVs) in children requiring surgical treatment of ureteropelvic junction (UPJ) obstructionand compare to laparoscopic findings. MATERIALS AND METHODS: Nineteen children ranging from 6 to 16 years of age underwent NC-MRA using the time-SLIP technique before surgery. Two independent readers analysed the MRA images. Number of renal arteries and presence or absence of CRVs were identified and compared with surgicalfindings. Image quality was assessed, as well as the presence of CRVs and measurement of renal pelvis diameter. Intra and inter-reader agreement was calculated using Cohen's kappa coefficient and Bland-Altman plots. RESULTS: The overall image quality was fair or good in 88% of cases. NC-MRA demonstrated CRVs at the level of the obstruction in 10 children and no CRV in 9 children. All were confirmed intra-operatively except in one of the nine children. Sensitivity, specificity, NPV, PPV for predicting CRVs were 92%, 100%, 100% and 87.5%, respectively, for both readers. CONCLUSION: NC-MRA is a good alternative to contrast-enhanced MRA and CT scanning for identifying CRVs in children with symptomatic UPJ. KEY POINTS: • Time-SLIP technique offers acceptable imaging quality for identifying crossing renal vessel. • Time-SLIP technique is easy to apply to the renal MRA examination. • Time-SLIP technique is an alternative to contrast-enhanced MRA and CT scanning.