Safety outcomes and improvement in pain scores after radiologist-performed fluoroscopy-guided interlaminar cervical epidural steroid injection.

INTRODUCTION: Image-guided spine injections are an important tool in the management of patients with a variety of spinal pathologies. Our practice offers radiologist-performed fluoroscopy-guided interlaminar cervical epidural steroid injection (ESI) routinely performed in the outpatient setting. The purpose of this study was to evaluate clinical outcomes and improvement in pain scores after radiologist-performed cervical ESI. METHODS: An institutional database was used to retrospectively identify cervical injections performed between October 2016 and October 2022. All injections were performed at the C7-T1 level utilizing 1.0 mL of 10 mg/mL dexamethasone without epidural anesthetic. The Numerical Rating Scale (NRS) was used to assess pain improvement. Cervical MRI was reviewed to assess pre-injection cervical disease severity. Patient charts were reviewed for any post-injection complications. RESULTS: A total of 251 cervical injections in 186 patients met our inclusion criteria with mean clinical follow up of 28.5 months (range 0.2 - 73.0 months). No patients experienced any major complications after injection. Post-injection pain scores were available for 218 of 251 injections (86.9%) with mean follow-up of 11.8 days (range 6 - 57 days). There was a significant improvement in pain scores from a mean pre-injection NRS score of 5.2/10 to 3.0/10 (p < .0001). 117 patients (53.7%) reported ≥ 50% improvement after injection. Patients who had prior injection were more likely to report ≥ 50% pain improvement after subsequent injection (p = .012). CONCLUSION: Radiologist-performed fluoroscopy-guided interlaminar cervical ESI at the C7-T1 level is a safe and effective tool in the management of patients with cervical pathology.

MRI features associated with HCC histologic subtypes: a western American and European bicenter study.

OBJECTIVES: To evaluate if preoperative MRI can predict the most frequent HCC subtypes in North American and European patients treated with surgical resection. METHODS: A total of 119 HCCs in 97 patients were included in the North American group and 191 HCCs in 176 patients were included in the European group. Lesion subtyping was based on morphologic features and immuno-histopathological analysis. Two radiologists reviewed preoperative MRI and evaluated the presence of imaging features including LI-RADS major and ancillary features to identify clinical, biologic, and imaging features associated with the main HCC subtypes. RESULTS: Sixty-four percent of HCCs were conventional. The most frequent subtypes were macrotrabecular-massive (MTM-15%) and steatohepatitic (13%). Necrosis (OR = 3.32; 95% CI: 1.39, 7.89; p = .0064) and observation size (OR = 1.011; 95% CI: 1.0022, 1.019; p = .014) were independent predictors of MTM-HCC. Fat in mass (OR = 15.07; 95% CI: 6.57, 34.57; p < .0001), tumor size (OR = 0.97; 95% CI: 0.96, 0.99; p = .0037), and absence of chronic HCV infection (OR = 0.24; 95% CI: 0.084, 0.67; p = .0068) were independent predictors of steatohepatitic HCC. Independent predictors of conventional HCCs were viral C hepatitis (OR = 3.20; 95% CI: 1.62, 6.34; p = .0008), absence of fat (OR = 0.25; 95% CI: 0.12, 0.52; p = .0002), absence of tumor in vein (OR = 0.34; 95% CI: 0.13, 0.84; p = .020), and higher tumor-to-liver ADC ratio (OR = 1.96; 95% CI: 1.14, 3.35; p = .014) CONCLUSION: MRI is useful in predicting the most frequent HCC subtypes even in cohorts with different distributions of liver disease etiologies and tumor subtypes which might have future treatment and management implications. KEY POINTS: • Representation of both liver disease etiologies and HCC subtypes differed between the North American and European cohorts of patients. • Retrospective two-center study showed that liver MRI is useful in predicting the most frequent HCC subtypes.

MRA of the Supraaortic Vasculature: Comparison of Gadobutrol and Gadoterate Meglumine at 1.5 T.

BACKGROUND: Gadobutrol (GB) and gadoterate meglumine (GM) are contrast agents used for contrast-enhanced magnetic resonance angiography (CEMRA). Supraaortic vasculature (SAV) CEMRAs are used to evaluate stroke risk and neurologic symptoms. There is a need to compare the SAV CEMRA image quality obtained with GB and GM. PURPOSE: To intra-individually compare MRA images obtained with equimolar GB and GM at 1.5 T in the SAV. STUDY TYPE: Prospective, crossover. POPULATION: Twenty-eight subjects (54 ± 13 years; 17 female). FIELD STRENGTH/SEQUENCE: 1.5 T; three-dimensional (3D) gradient recalled echo. ASSESSMENT: Quantitative image quality was measured by normalized signal intensity (SIn ) [SIn  = SI blood/SD blood] and contrast ratio (CR) [CR = SI blood/SI muscle], determined by an observer (JWC) with 1 year of vascular imaging experience. Three radiologists (AS, PA, and MU) with (5, 5, and 6 years of) vascular imaging experience evaluated image quality by Likert-scale ratings (of image impression, wall conspicuity, and artifact absence). STATISTICAL TESTS: SIn and CR were compared with paired t-tests or Wilcoxon signed-rank tests and Bland-Altman plots. Qualitative ratings were compared with Wilcoxon signed-rank test. RESULTS: No significant difference in SIn was found between GB and GM. CRs with GB were significantly higher than GM at the right common carotid (6.9 ± 2.5 vs. 4.8 ± 1), left internal carotid (7.3 ± 2 vs. 4.4 ± 1.2), right internal carotid (7.7 ± 2.2 vs. 5 ± 1.1), and left vertebral (6.6 ± 2.2 vs. 4.5 ± 1.1) arteries. Bland-Altman plots showed relatively greater differences between GB and GM at higher CRs and SIn s. GM showed significantly higher artifact than GB (3.56 ± 0.52 vs. 3.36 ± 0.46) and significantly lower overall image quality (10.73 ± 1.45 vs. 11.26 ± 1.58) at the left vertebral artery. DATA CONCLUSION: At 1.5 T and equimolar demonstration, GB (0.1 mL/kg, i.e., 0.1 mmol/kg) showed higher CRs in the SAV compared to GM (0.2 mL/kg, i.e., 0.1 mmol/kg) at most vessels. Subjective image quality was not significantly different between the two agents for most vessels. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Musculoskeletal Manifestations of COVID-19: Currently Described Clinical Symptoms and Multimodality Imaging Findings.

COVID-19, the clinical syndrome produced by infection with SARS-CoV-2, can result in multisystem organ dysfunction, including respiratory failure and hypercoagulability, which can lead to critical illness and death. Musculoskeletal (MSK) manifestations of COVID-19 are common but have been relatively underreported, possibly because of the severity of manifestations in other organ systems. Additionally, patients who have undergone sedation and who are critically ill are often unable to alert clinicians of their MSK symptoms. Furthermore, some therapeutic measures such as medications and vaccinations can worsen existing MSK symptoms or cause additional symptoms. Symptoms may persist or occur months after the initial infection, known as post-COVID condition or long COVID. As the global experience with COVID-19 and the vaccination effort increases, certain patterns of MSK disease involving the bones, muscles, peripheral nerves, blood vessels, and joints have emerged, many of which are likely related to a hyperinflammatory host response, prothrombotic state, or therapeutic efforts rather than direct viral toxicity. Imaging findings for various COVID-19-related MSK pathologic conditions across a variety of modalities are being recognized, which can be helpful for diagnosis, treatment guidance, and follow-up. The online slide presentation from the RSNA Annual Meeting is available for this article. ©RSNA, 2022.

Highly accelerated aortic 4D flow MRI using compressed sensing: Performance at different acceleration factors in patients with aortic disease.

PURPOSE: To systematically assess the feasibility and performance of a highly accelerated compressed sensing (CS) 4D flow MRI framework at three different acceleration factors (R) for the quantification of aortic flow dynamics and wall shear stress (WSS) in patients with aortic disease. METHODS: Twenty patients with aortic disease (58 ± 15 y old; 19 M) underwent four 4D flow scans: one conventional (GRAPPA, R = 2) and three CS 4D flows with R = 5.7, 7.7, and 10.2. All scans were acquired with otherwise equivalent imaging parameters on a 1.5T scanner. Peak-systolic velocity (Vmax ), peak flow (Qmax ), and net flow (Qnet ) were quantified at the ascending aorta (AAo), arch, and descending aorta (DAo). WSS was calculated at six regions within the AAo and arch. RESULTS: Mean scan times for the conventional and CS 4D flows with R = 5.7, 7.7, and 10.2 were 9:58 ± 2:58 min, 3:40 ± 1:19 min, 2:50 ± 0:56 min, and 2:05 ± 0:42 min, respectively. Vmax , Qmax , and Qnet were significantly underestimated by all CS protocols (underestimation ≤ -7%, -9%, and -10% by CS, R = 5.7, 7.7, and 10.2, respectively). WSS measurements showed the highest underestimation by all CS protocols (underestimation ≤ -9%, -12%, and -14% by CS, R = 5.7, 7.7, and 10.2). CONCLUSIONS: Highly accelerated aortic CS 4D flow at R = 5.7, 7.7, and 10.2 showed moderate agreement with the conventional 4D flow, despite systematically underestimating various hemodynamic parameters. The shortened scan time may enable the clinical translation of CS 4D flow, although potential hemodynamic underestimation should be considered when interpreting the results.

Evaluation of image quality of wideband single-shot late gadolinium-enhancement MRI in patients with a cardiac implantable electronic device.

INTRODUCTION: While wideband segmented, breath-hold late gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) has been shown to suppress image artifacts associated with cardiac-implanted electronic devices (CIEDs), it may produce image artifacts in patients with arrhythmia and/or dyspnea. Single-shot LGE is capable of suppressing said artifacts. We sought to compare the performance of wideband single-shot free-breathing LGE against the standard and wideband-segmented LGEs in CIED patients. METHODS AND RESULTS: We retrospectively identified all 54 consecutive patients (mean age: 61 ± 15 years; 31% females) with CIED who had undergone CMR with standard segmented, wideband segmented, and/or wideband single-shot LGE sequences as part of quality assurance for determining best clinical practice at 1.5 T. Two raters independently graded the conspicuity of myocardial scar or normal myocardium and the presence of device artifact level on a 5-point Likert scale (1: worst; 3: acceptable; 5: best). Summed visual score (SVS) was calculated as the sum of conspicuity and artifact scores (SVS ≥ 6 defined as diagnostically interpretable). Median conspicuity and artifact scores were significantly better for wideband single-shot LGE (F = 24.2, p < .001) and wideband-segmented LGE (F = 20.6, p < .001) compared to standard-segmented LGE. Among evaluated myocardial segments, 72% were deemed diagnostically interpretable-defined as SVS ≥ 6-for standard-segmented LGE, 89% were deemed diagnostically interpretable for wideband-segmented LGE, and 94% segments were deemed diagnostically interpretable for wideband single-shot LGE. CONCLUSIONS: Wideband single-shot LGE and wideband-segmented LGE produced similarly improved image quality compared to standard LGE.

Documentation of normal shape and measurements of the uterine fundus at reproductive age.

BACKGROUND: The diagnosis of congenital uterine anomalies and the differentiation between different subtypes is based on various sets of measurements that are difficult to implement during daily workflow. PURPOSE: To describe the shape and range of measurements of the normal uterus at the fundus in women of reproductive age. MATERIAL AND METHODS: This retrospective study was conducted on 200 pelvic magnetic resonance imaging (MRI) examinations of female patients of reproductive age with normal uteri divided into three age groups (15-24 years, 25-34 years, 35-45 years). The shape of the endometrium and serosa were documented. The thickness from the external to the internal fundic contour and the intercornual distance were measured. RESULTS: The shape of endometrium is most commonly concave or flat but is not uncommonly convex. The shape of the serosa is convex in most cases but can be flat or concave. There is a progressive increase in thickness at the fundus with increased age with mean values of 10.8, 12.3, and 13.6 mm and ranges of 5.6-15.8 mm, 7-18.7 mm, and 7.3-19.8 mm, respectively, in the first, second, and third age groups. There is a progressive increase in intercornual distance with age with mean values of 41.4, 44.5, 47.2 mm and ranges of 30.6-50.7 mm, 31.5-57.3 mm, and 35.2-61 mm, respectively, in the first, second, and third age groups. CONCLUSION: Our study reports the range of normality in shape and measurement of the uterine fundus to aid in the detection of congenital uterine abnormalities.

Radial-based acquisition strategies for pre-procedural non-contrast cardiovascular magnetic resonance angiography of the pulmonary veins.

BACKGROUND: Computed tomography angiography (CTA) or contrast-enhanced (CE) cardiovascular magnetic resonance angiography (CMRA) is often obtained in patients with atrial fibrillation undergoing evaluation prior to pulmonary vein (PV) isolation. Drawbacks of CTA include radiation exposure and potential risks from iodinated contrast agent administration. Free-breathing 3D balanced steady-state free precession (bSSFP) Non-contrast CMRA is a potential imaging option, but vascular detail can be suboptimal due to ghost artifacts and blurring that tend to occur with a Cartesian k-space trajectory or, in some cases, inconsistent respiratory gating. We therefore explored the potential utility of both breath-holding and free-breathing non-contrast CMRA, using radial k-space trajectories that are known to be less sensitive to flow and motion artifacts than Cartesian. MAIN BODY: Free-breathing 3D Cartesian and radial stack-of-stars acquisitions were compared in 6 healthy subjects. In addition, 27 patients underwent CTA and non-contrast CMRA for PV mapping. Three radial CMR acquisition strategies were tested: (1) breath-hold (BH) 2D radial bSSFP (BH-2D); (2) breath-hold, multiple thin-slab 3D stack-of-stars bSSFP (BH-SOS); and (3) navigator-gated free-breathing (FB) 3D stack-of-star bSSFP using a spatially non-selective RF excitation (FB-NS-SOS). A non-rigid registration algorithm was used to compensate for variations in breath-hold depth. In healthy subjects, image quality and vessel sharpness using a free-breathing 3D SOS acquisition was significantly better than free-breathing (FB) Cartesian 3D. In patients, diagnostic image quality was obtained using all three radial CMRA techniques, with BH-SOS and FB-NS-SOS outperforming BH-2D. There was overall good correlation for PV maximal diameter between BH-2D and CTA (ICC = 0.87/0.83 for the two readers), excellent correlation between BH-SOS and CTA (ICC = 0.90/0.91), and good to excellent correlation between FB-NS-SOS and CTA (ICC = 0.87/0.94). For PV area, there was overall good correlation between BH-2D and CTA (ICC = 0.79/0.83), good to excellent correlation between BH-SOS and CTA (ICC = 0.88/0.91) and excellent correlation between FB-NS-SOS and CTA (ICC = 0.90/0.95). CNR was significantly higher with BH-SOS (mean = 11.04) by comparison to BH-2D (mean = 6.02; P = 0.007) and FB-NS-SOS (mean = 5.29; P = 0.002). CONCLUSION: Our results suggest that a free-breathing stack-of-stars bSSFP technique is advantageous in providing accurate depiction of PV anatomy and ostial measurements without significant degradation from off-resonance artifacts, and with better image quality than Cartesian 3D. For patients in whom respiratory gating is unsuccessful, a breath-hold thin-slab stack-of-stars technique with retrospective motion correction may be a useful alternative.

Ethylene Vinyl Alcohol Copolymer Embolization for Acute Renal Hemorrhage: Initial Experience in 24 Cases.

OBJECTIVE. The purpose of this study was to assess the efficacy and safety of ethylene vinyl alcohol (EVOH) copolymer (Onyx, Medtronic) for embolization for acute renal hemorrhage. MATERIALS AND METHODS. Between October 2006 and June 2018, 24 consecutive patients were treated by embolization with EVOH copolymer for acute renal hemorrhage at Hôpital Bichat-Claude-Bernard. CT angiography was performed in all patients before treatment. Technical success was defined as the complete occlusion of the bleeding artery on final renal angiogram. Clinical success was defined as the absence of rebleeding after embolization. Complications mid procedure, infarcted renal area on final angiogram, and renal function 1 week after embolization were retrospectively analyzed. RESULTS. Active bleeding was observed in all cases. The causes of acute renal hemorrhage were iatrogenic in 12 patients, vascular malformation in four patients, renal tumor in four patients, and unknown in four patients. EVOH copolymer was the sole embolic agent used in 16 patients. In eight patients, EVOH copolymer was used after persistent bleeding after embolization with coils. Technical and clinical success rates were 100%. No patient required surgery or new embolization during a mean follow-up period of 35 months (range, 6-86 months). No serious complications were attributable to EVOH copolymer. The mean infarcted renal area was 10% (range, 5-30%). Renal function, available for 16 (67%) patients, was not altered 1 week after embolization. CONCLUSION. EVOH copolymer is safe and effective for embolization of acute renal hemorrhage, either as a first-line embolic agent or after failure of coil embolization.

Accelerated, free-breathing, noncontrast, electrocardiograph-triggered, thoracic MR angiography with stack-of-stars k-space sampling and GRASP reconstruction.

PURPOSE: To develop an accelerated, free-breathing, noncontrast, electrocardiograph-triggered, thoracic MR angiography (NC-MRA) pulse sequence capable of achieving high spatial resolution at clinically acceptable scan time and test whether it produces clinically acceptable image quality in patients with suspected aortic disease. METHODS: We modified a "coronary" MRA pulse sequence to use a stack-of-stars k-space sampling pattern and combined it with golden-angle radial sparse parallel (GRASP reconstruction to enable self-navigation of respiratory motion and high data acceleration. The performance of the proposed NC-MRA was evaluated in 13 patients, where clinical standard contrast-enhanced MRA (CE-MRA) was used as control. For visual analysis, two readers graded the conspicuity of vessel lumen, artifacts, and noise level on a 5-point scale (overall score index = sum of three scores). The aortic diameters were measured at seven standardized locations. The mean visual scores, inter-observer variability, and vessel diameters were compared using appropriate statistical tests. RESULTS: The overall mean visual score index (12.1 ± 1.7 for CE-MRA versus 12.1 ± 1.0 for NC-MRA) scores were not significantly different (P > 0.16). The two readers' scores were significantly different for CE-MRA (P = 0.01) but not for NC-MRA (P = 0.21). The mean vessel diameters were not significantly different, except at the proximal aortic arch (P < 0.03). The mean diameters were strongly correlated (R2 ≥ 0.96) and in good agreement (absolute mean difference ≤ 0.01 cm and 95% confidence interval ≤ 0.62 cm). CONCLUSION: This study shows that the proposed NC-MRA produces clinically acceptable image quality in patients at high spatial resolution (1.5 mm × 1.5 mm × 1.5 mm) and clinically acceptable scan time (~6 min).

Feasibility of Image Fusion for Concurrent MRI Evaluation of Vessel Lumen and Vascular Calcifications in Peripheral Arterial Disease.

OBJECTIVE: With MR angiography of peripheral arterial disease, calcifications are unapparent, so a separate calcification-sensitive pulse sequence (proton density-weighted in-phase 3D stack-of-stars [PDIP-SOS]) is needed for complete assessment. We hypothesized that, despite being acquired separately, MR angiography and PDIP-SOS images could be coregistered and fused without loss of significant diagnostic information. CONCLUSION: In a prospective study of 15 patients, MR image fusion enabled the simultaneous display of vessel lumen and vascular calcifications similarly to CT angiography.

Cardiovascular cine imaging and flow evaluation using Fast Interrupted Steady-State (FISS) magnetic resonance.

BACKGROUND: Existing cine imaging techniques rely on balanced steady-state free precession (bSSFP) or spoiled gradient-echo readouts, each of which has limitations. For instance, with bSSFP, artifacts occur from rapid through-plane flow and off-resonance effects. We hypothesized that a prototype cine technique, radial fast interrupted steady-state (FISS), could overcome these limitations. The technique was compared with standard cine bSSFP for cardiac function, coronary artery conspicuity, and aortic valve morphology. Given its advantageous properties, we further hypothesized that the cine FISS technique, in combination with arterial spin labeling (ASL), could provide an alternative to phase contrast for visualizing in-plane flow patterns within the aorta and branch vessels. MAIN BODY: The study was IRB-approved and subjects provided consent. Breath-hold cine FISS and bSSFP were acquired using similar imaging parameters. There was no significant difference in biplane left ventricular ejection fraction or cardiac image quality between the two techniques. Compared with cine bSSFP, cine FISS demonstrated a marked decrease in fat signal which improved conspicuity of the coronary arteries, while suppression of through-plane flow artifact on thin-slice cine FISS images improved visualization of the aortic valve. Banding artifacts in the subcutaneous tissues were reduced. In healthy subjects, dynamic flow patterns were well visualized in the aorta, coronary and renal arteries using cine FISS ASL, even when the slice was substantially thicker than the vessel diameter. CONCLUSION: Cine FISS demonstrates several benefits for cardiovascular imaging compared with cine bSSFP, including better suppression of fat signal and reduced artifacts from through-plane flow and off-resonance effects. The main drawback is a slight (~ 20%) decrease in temporal resolution. In addition, preliminary results suggest that cine FISS ASL provides a potential alternative to phase contrast techniques for in-plane flow quantification, while enabling an efficient, visually-appealing, semi-projective display of blood flow patterns throughout the course of an artery and its branches.

Cardiovascular magnetic resonance imaging of aorto-iliac and ilio-femoral vascular calcifications using proton density-weighted in-phase stack of stars.

BACKGROUND: Comparing cardiovascular magnetic resonance (CMR) angiography with computed tomography angiography (CTA), a major deficiency has been its inability to reliably image peripheral vascular calcifications that may impact the choice of interventional strategy and influence patient prognosis. Recently, MRI using a proton density-weighted, in-phase stack of stars (PDIP-SOS) technique has proved capable of detecting these calcifications. The goal of the present study was two-fold: (1) to determine whether magnetic field strength impacts the apparent size and conspicuity of ilio-femoral arterial calcifications; and (2) to determine whether the technique can be accurately applied to image aorto-iliac arterial calcifications. MAIN BODY: Two patient cohorts were studied. For the first cohort, ilio-femoral arterial calcifications were imaged at 1.5 Tesla in 20 patients and at 3 Tesla in 12 patients. For the second cohort, aorto-iliac arterial calcifications were imaged in 10 patients at 3 Tesla and one patient at 1.5 Tesla. Qualitative image analysis as well as quantitative analysis using a semi-automated technique were performed using CTA as the reference standard. Qualitatively, most PDIP-SOS CMR images showed good-to-excellent confidence to detect vascular calcifications, with good-to-excellent inter-reader agreement (κ = 0.67 for ilio-femoral region, P < 0.001; κ = 0.80 for aorto-iliac region, P < 0.01). There was an overall excellent correlation (r = 0.98, P < 0.001) and agreement (intraclass correlation coefficient = 0.97, P < 0.001) between PDIP-SOS CMR and CTA measures of calcification volume in both regions, with no overt difference in performance at 1.5 Tesla vs. 3 Tesla for ilio-femoral calcifications. CMR lesion volumes were slightly lower than those measured for CTA. CONCLUSION: Using PDIP-SOS CMR, aorto-iliac and ilio-femoral calcifications could be simultaneously evaluated at 3 Tesla in less than six minutes with excellent correlation and agreement to CTA. Our results suggest that PDIP-SOS CMR provides a reliable alternative to CT for pre-interventional evaluation of peripheral vascular calcium burden.

Von Hippel-Lindau Disease (VHL): Characteristic Lesions with Classic Imaging Findings.

Von Hippel-Lindau disease (VHL) is a multisystem cancer syndrome caused by the inactivation of the VHL tumor suppressor gene and involves various organ systems including the central nervous system (CNS), endocrine system, and the kidneys. Tumors seen in patients with VHL disease can be benign or malignant and are usually multifocal, bilateral, and hypervascular in nature. As most lesions associated with VHL are asymptomatic initially, early diagnosis and the institution of an evidence-based surveillance protocol are of paramount importance. Screening, surveillance, and genetic counseling are key aspects in the management of patients diagnosed with VHL disease and often require a multidisciplinary approach and referral to specialized centers. This article will discuss the characteristic lesions seen with VHL disease, their diagnosis, screening protocols and management strategies, as well as an illustrative case to demonstrate the natural progression of the disease with classic imaging findings.

Role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of peripheral nerves in the upper extremity.

Upper extremity entrapment neuropathies are common conditions in which peripheral nerves are prone to injury at specific anatomical locations, particularly superficial regions or within fibro-osseous tunnels, resulting in pain and potential disability. Although neuropathy is primarily diagnosed clinically by physical examination and electrophysiology, imaging evaluation with ultrasound and magnetic resonance neurography are valuable complementary non-invasive and accurate tools for evaluation and can help define the site and cause of nerve dysfunction which ultimately leads to precise and timely treatment. Ultrasound, which has higher spatial resolution, can quickly and comfortably characterize the peripheral nerves in real time and can evaluate for denervation related muscle atrophy. Magnetic resonance imaging on the other hand provides excellent contrast resolution between the nerves and adjacent tissues, also between pathologic and normal segments of peripheral nerves. It can also assess the degree of muscle denervation and atrophy. As a prerequisite for nerve imaging, radiologists and sonographers should have a thorough knowledge of anatomy of the peripheral nerves and their superficial and deep branches, including variant anatomy, and the motor and sensory territories innervated by each nerve. The purpose of this illustrative article is to review the common neuropathy and nerve entrapment syndromes in the upper extremities focusing on ultrasound and magnetic resonance neurography imaging.

Sural nerve: imaging anatomy and pathology.

High resolution ultrasound (US) and magnetic resonance (MR) neurography are both imaging modalities that are commonly used for assessing peripheral nerves including the sural nerve (SN). The SN is a cutaneous sensory nerve which innervates the lateral ankle and foot to the base of the fifth metatarsal. It is formed by contributing nerves from the tibial and common peroneal nerves with six patterns and multiple subtypes described in literature. In addition to the SN being a cutaneous sensory nerve, the superficial location enables the nerve to be easily biopsied and harvested for a nerve graft, as well as increasing the susceptibility to traumatic injury. As with any peripheral nerves, pathologies such as peripheral nerve sheath tumors and neuropathies can also affect the SN. By utilizing a high frequency probe in US and high-resolution MR neurography, the SN can be easily identified even with the multiple variations given the standard distal course. US and MRI are also useful in determining pathology of the SN given the specific image findings that are seen with peripheral nerves. In this review, we evaluate the normal imaging anatomy of the SN and discuss common pathologies identified on imaging.

The role of high-resolution ultrasound and MRI in the evaluation of peripheral nerves in the lower extremity.

Lower extremity peripheral neuropathy is a commonly encountered neurologic disorder, which can lead to chronic pain, functional disability, and decreased quality of life for a patient. As diagnostic imaging modalities have improved, imaging has started to play an integral role in the detection and characterization of peripheral nerve abnormalities by non-invasively and accurately identifying abnormal nerves as well as potential causes of neuropathy, which ultimately leads to precise and timely treatment. Ultrasound, which has high spatial resolution and can quickly and comfortably characterize peripheral nerves in real time along with associated denervation muscle atrophy, and magnetic resonance neurography, which provides excellent contrast resolution between nerves and other tissues and between pathologic and normal segments of peripheral nerves, in addition to assessing reversible and irreversible muscle denervation changes, are the two mainstay imaging modalities used in peripheral nerve assessment. These two modalities are complimentary, and one may be more useful than the other depending on the nerve and location of pathology. Imaging must be interpreted in the context of available clinical information and other diagnostic studies, such as electrodiagnostic tests. Here, we offer a comprehensive overview of the role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of the peripheral nerves of the lower extremity and their associated neuropathies.

MRI evaluation of solid soft tissue masses of the fingers with pathology correlation.

OBJECTIVE: Space occupying lesions of the fingers are commonly encountered in clinical and radiology practice. The objective of this study was to determine the characteristics of these lesions on MRI and to correlate with surgical pathology results. MATERIAL AND METHODS: This IRB-approved HIPAA-compliant study retrospectively evaluated the clinical, imaging and pathology findings of 100 consecutive patients referred for evaluation of solid soft tissue masses of the fingers. Only solid lesions with MR imaging prior to surgery were included in this study. MR images and when available corresponding radiographs were evaluated by two radiologist in regard to signal characteristics, relation to surrounding structures and enhancement. All masses were classified into different groups based on pathology results. RESULTS: Tenosynovial giant cell tumor (TSGCT) and fibroma of the tendon sheath were the most common solid tumors (36 %) and malignant tumors represent only 5% of the cohort. 70 % of masses with low T2 signal were TSGCT and fibroma of tendon sheath; 100 % of masses with peripheral high T2 signal and central low T2 signal/thrombus were vascular lesions, representing 41 % of the total vascular lesions in the cohort. Additionally, 100 % of serpiginous/tubular shaped masses were vascular lesions and 67 % of masses with infiltrative borders were malignant masses. Enhancement was important in identifying solid lesions but there was no statistical difference between groups related to enhancement pattern. There was a good agreement for all analyses between both readers. CONCLUSION: Typical MR findings can help to narrow the differential diagnosis in the evaluation of finger masses and provide crucial information to guide further management.

Evaluation of Renal Allograft Vasculature Using Non-contrast 3D Inversion Recovery Balanced Steady-state Free Precession MRA and 2D Quiescent-interval Slice-selective MRA.

BACKGROUND AND OBJECTIVES: Renal transplant patients often require periodic imaging to evaluate the transplant vessel anastomosis for potential vascular complications. The use of non-contrast enhanced magnetic resonance angiography (NCE-MRA) techniques is encouraged in these patients because they are at increased risk of nephrogenic systemic fibrosis (NSF) due to their renal insufficiency. This study aimed to evaluate the performance of two NCE-MRA techniques (three-dimensional [3D] balanced steady-state free precession [bSSFP] with inversion recovery and quiescent-interval slice-selective [QISS]) for the evaluation of renal allograft vasculature in patients with clinical suspicion, or Doppler ultrasound, or both of arterial anastomotic stenosis. METHODS: A total of 43 patients were included in this retrospective study. Two radiologists independently scored the images from 3D bSSFP and QISS MRA sequences for image quality and confidence in anastomosis interpretation, and the degree of stenosis at the arterial anastomosis. Correlations with digital subtraction angiography (DSA) were carried out when available. In addition, inter-rater agreement was calculated. RESULTS: In total, 43 patients underwent QISS and 3D bSSFP MRA. For QISS, all cases were adequate for evaluation. For 3D SSFP, 86% of cases were adequate for evaluation. There was a good-to-excellent inter-rater agreement for all scores and an excellent correlation between NCE-MRA and DSA results when available (12 patients). CONCLUSIONS: QISS and 3D SSFP showed good inter-rater agreement for image quality and stenosis grade, with more cases being of adequate image quality that used QISS. Further study is required; however, NCE-MRA shows potential as a risk-free alternative to CTA and contrast-enhanced MRA (CE-MRA) for the evaluation of arterial anastomoses in renal transplant patients.

Aortic annular dimensions by non-contrast MRI using k-t accelerated 3D cine b-SSFP in pre-procedural assessment for transcatheter aortic valve implantation: a technical feasibility study.

To evaluate k-t accelerated 3D cine b-SSFP (balanced steady state free precession) as magnetic resonance imaging (MRI) technique for aortic annular area measurement in transcatheter aortic valve replacement (TAVR) planning compared to computed tomography angiography (CTA) and other non-contrast MRI sequences with reduced imaging time and without contrast administration. 6 volunteers and 7 TAVR candidates were prospectively enrolled. The volunteers underwent an MRI while TAVR candidates underwent an MRI and CTA. The following non-contrast MRI sequences were obtained at the level of the aortic root: 2D cine b-SSFP [GRAPPA (GeneRalized Autocalibrating Partially Parallel Acquisitions), R = 2], 3D cine b-SSFP [GRAPPA R = 2], navigator triggered 3D b-SSFP MRA [GRAPPA, R = 2] and k-t accelerated 3D cine b-SSFP [PEAK GRAPPA, R = 5]. Qualitative analysis and aortic annular area measurements in systole and diastole were obtained. k-t accelerated 3D cine b-SSFP provided image quality that is acceptable for confident diagnosis with very good interrater agreement. There was no statistically significant difference in aortic annular measurements between k-t accelerated 3D cine b-SSFP and CTA or other MRI sequences (p > 0.05). Bland-Altman analysis showed no systemic difference of annular area measurements between k-t accelerated 3D cine b-SSFP and each of the other techniques. There was excellent inter-rater agreement on aortic annular area measurements during systolic (ICC = 0.976, p < 0.001) and diastolic (ICC = 0.971, p < 0.001) phases using k-t accelerated 3D cine b-SSFP. K-t accelerated 3D cine b-SSFP is a promising alternative for the assessment of annular sizing in pre-TAVR evaluation while offering a reasonable combination of imaging parameters during one breath-hold.