Multiplanar reformation improves identification of the anterolateral ligament with MRI of the knee

The anterolateral ligament (ALL) is subject of the current debate concerning rotational stability in case of anterior cruciate ligament (ACL) injuries. Today, reliable anatomical and biomechanical evidence for its existence and course is available. Some radiologic studies claim to be able to identify the ALL on standard coronal plane MRI sections. In the experience of the authors, however, ALL identification on standard MRI sequences frequently fails and is prone to errors. The reason for this mainly lies in the fact, that the entire ALL often cannot be identified on a single MRI image. This study aimed to establish an MRI evaluation protocol improving the visualization of the ALL, using multiplanar reformation (MPR) with the goal to be able to evaluate the ALL on one MRI image. A total of 47 knee MRIs performed due to atraumatic knee pain between 2018 and 2019 without any pathology were analyzed. Identification of the ALL was performed twice by an orthopedic surgeon and a radiologist on standard coronal plane and after MPR. For the latter axial and coronal alignment was obtained with the femoral condyles as a reference. Then the coronal plane was adjusted to the course of the ALL with the lateral epicondyle as proximal reference. Visualization of the ALL was rated as “complete” (continuous ligamentous structure with a tibial and femoral insertion visible on one coronal image), “partial” (only parts of the ALL like the tibial insertion were visible) and “not visible”. The distances of its tibial insertion to the bony joint line, Gerdy’s tubercle and the tip of the fibular head were measured. On standard coronal images the ALL was fully visible in 17/47, partially visible in 27/47, and not visible in 3/47 cases. With MPR the ALL was fully visible in 44/47 and not visible in 3/47 cases. The median distance of its tibial insertion to the bony joint line, Gerdy’s tubercle and the tip of the fibular head were 9, 21 and 25 mm, respectively. The inter- (ICC: 0.612; 0.645; 0.757) and intraobserver (ICC: 0.632; 0.823; 0.857) reliability was good to excellent. Complete visualization of the ALL on a single MRI image is critical for its identification and evaluation. Applying multiplanar reformation achieved reliable full-length visualization of the ALL in 94% of cases. The described MPR technique can be applied easily and fast in clinical routine. It is a reliable tool to improve the assessment of the ALL.

Preoperative estimate of natural ureteral length based on computed tomography and/or plain radiography

To predict natural ureter lengths based on clinical images. We reviewed our image database of patients who underwent multiphasic computed tomography urography from January 2019 to April 2020. Natural ureteral length (ULCTU) was measured using a three-dimensional curved multiplanar reformation technique. Patient parameters including age, height, and height of the lumbar spine, the index of ureteral length using kidney/ureter/bladder (KUB) radiographs (C-P and C-PS) and computed tomography (ULCT) were collected. ULCTU correlated most strongly with ULCT. R square and adjusted R square values from multivariate regression were 0.686 and 0.678 (left side) and 0.516 and 0.503 (right side), respectively. ULCTU could be estimated by the regression model in three different scenarios as follows: ULCT + C-P ULCTUL = 0.405 $$\times$$ × ULCTL$$+$$ + 0.626 $$\times$$ × C-PL – 0.508 cm ULCTUR = 0.558 $$\times$$ × ULCTR$$+$$ + 0.218 $$\times$$ × C-PR + 6.533 cm ULCT ULCTUL = 0.876 $$\times$$ × ULCTL$$+$$ + 6.337 cm ULCTUR = 0.710 $$\times$$ × ULCTR$$+$$ + 9.625 cm C-P ULCTUL = 0.678 $$\times$$ × C-PL$$+$$ + 4.836 cm ULCTUR = 0.495 $$\times$$ × C-PR$$+$$ + 10.353 cm We provide equations to predict ULCTU based on CT, KUB or CT plus KUB for different clinical scenarios. The formula based on CT plus KUB provided the most accurate estimation, while the others had lower validation values but could still meet clinical needs.

An MRI study of the tibial nerve in the ankle canal and its branches: a method of multiplanar reformation with 3D-FIESTA-C sequences

Background The visualization of the tibial nerve and its branches in the ankle canal is helpful for the diagnosis of local lesions and compression, and it is also useful for clinical observation and surgical planning. The aim of this study was to investigate the feasibility of three-dimensional dual-excitation balanced steady-state free precession sequence (3D-FIESTA-C) multiplanar reformation (MPR) display of the tibial nerve and its branches in the ankle canal. Methods The subjects were 20 healthy volunteers (40 ankles), aged 22–50 years, with no history of ankle joint disease. The 3D-FIESTA-C sequence was used in the 3.0 T magnetic resonance equipment for imaging. During scanning, each foot was at an angle of 90° to the tibia. The tibial nerve of the ankle canal and its branches were displayed and measured at the same level through MPR. Results Most of the tibial nerve bifurcation points were located in the ankle canal (57.5%), few bifurcation points (42.5%) were located at the proximal end of the ankle canal, and none of them were found away from the distal end. The bifurcation between the medial plantar nerve and the lateral plantar nerve was on the line between the tip of the medial malleolus and the calcaneus, and it’s angle ranged between 6° and 35°. In MPR images, the display rates of both the medial calcaneal nerve and the subcalcaneal nerve were 100%, and the starting point of the subcalcaneal nerve was always at the distal end of the starting point of the medial calcaneal nerve. In 55% of cases, there were more than two medial calcaneal nerve innervations. Conclusion The 3D-FIESTA-C MPR can display the morphological features and positions of the tibial nerve and its branches and the bifurcation point’s projection position can be marked on the body surface. This method not only benefited the imaging diagnosis of the tibial nerve and branch-related lesions in the ankle canal, but it also provided a good imaging basis to plan a clinical operation of the ankle canal and avoid surgical injury.

Fast 3D Isotropic Proton Density-Weighted Fat-Saturated MRI of the Knee at 1.5 T with Compressed Sensing: Comparison with Conventional Multiplanar 2D Sequences

Purpose Compressed sensing (CS) is a method to accelerate MRI acquisition by acquiring less data through undersampling of k-space. In this prospective study we aimed to evaluate whether a three-dimensional (3D) isotropic proton density-weighted fat saturated sequence (PDwFS) with CS can replace conventional multidirectional two-dimensional (2D) sequences at 1.5 Tesla. Materials and Methods 20 patients (45.2 ± 20.2 years; 10 women) with suspected internal knee damage received a 3D PDwFS with CS acceleration factor 8 (acquisition time: 4:11 min) in addition to standard three-plane 2D PDwFS sequences (acquisition time: 4:05 min + 3:03 min + 4:46 min = 11:54 min) at 1.5 Tesla. Scores for homogeneity of fat saturation, image sharpness, and artifacts were rated by two board-certified radiologists on the basis of 5-point Likert scales. Based on these ratings, an overall image quality score was generated. Additionally, quantitative contrast ratios for the menisci (MEN), the anterior (ACL) and the posterior cruciate ligament (PCL) in comparison with the popliteus muscle were calculated. Results The overall image quality was rated superior in 3D PDwFS compared to 2D PDwFS sequences (14.45 ± 0.83 vs. 12.85 ± 0.99; p < 0.01), particularly due to fewer artifacts (4.65 ± 0.67 vs. 3.65 ± 0.49; p < 0.01) and a more homogeneous fat saturation (4.95 ± 0.22 vs. 4.55 ± 0.51; p < 0.01). Scores for image sharpness were comparable (4.80 ± 0.41 vs. 4.65 ± 0.49; p = 0.30). Quantitative contrast ratios for all measured structures were superior in 3D PDwFS (MEN: p < 0.05; ACL: p = 0.06; PCL: p = 0.33). In one case a meniscal tear was only diagnosed using multiplanar reformation of 3D PDwFS, but it would have been missed on standard multiplanar 2D sequences. Conclusion An isotropic fat-saturated 3D PD sequence with CS enables fast and high-quality 3D imaging of the knee joint at 1.5 T and may replace conventional multiplanar 2D sequences. Besides faster image acquisition, the 3D sequence provides advantages in small structure imaging by multiplanar reformation. Key Points: Citation Format

MRI Study on Tibial Nerve of the Ankle Canal and Its Branches:A method of multiplanar reconstruction with 3D-FIESTA-C sequences

Background: The display of tibial nerve and its branches in the ankle canal is helpful for the diagnosis of local lesions and compression, and also for clinical observation and surgical planning. The aim of this study was to investigate the feasibility of three-dimensional dual-excitation balanced steady-state free precession sequence (3D-FIESTA-C) multiplanar reformation (MPR) display of tibial nerve and its branches of the ankle canal.Methods: The subjects were 20 healthy volunteers (40 ankles), aged 22-50, with no history of ankle joint disease. 3D-FIESTA-C sequence was used in the 3.0t magnetic resonance equipment for imaging. During the scanning, each foot was at a 90-degree angle to the tibia. The tibial nerve of the ankle canal and its branches were displayed and measured at the same level through multiplanar reformation.Results: Most of the tibial nerve bifurcation points were located in the ankle canal (57.5%), few (42.5%) were located at the proximal end of the ankle canal, and none was found away from the distal end. The bifurcation between the medial plantar nerve and the lateral plantar nerve is on the line between the tip of the medial malleolus and the calcaneus, and it’s angle is between 6° and 35°. In MPR images, the display rates of both the medial calcaneal nerve and the subcal caneal nerve were 100%, and the starting point of the subcal caneal nerve was always at the distal end of the starting point of the medial calcaneal nerve. In 55% of cases, there were more than 2 medial calcaneal nerve innervations.Conclusion: The 3D-FIESTA-C MPR can display the morphological features and positions of tibial nerve and its branches and the bifurcation point’s projection position on the body surface can be marked. This method not only benefited the imaging diagnosis of tibial nerve and branch-related lesions of the ankle canal, but also provided a good imaging basis to plan the clinical operation of the ankle canal and avoid surgical injury.

Proposed modified diagnostic criteria for recurrent painful ophthalmoplegic neuropathy: Five case reports and literature review

Background Recurrent painful ophthalmoplegic neuropathy (RPON) is an uncommon disorder characterized by recurrent unilateral headache attacks associated with ipsilateral ophthalmoplegia. We intend to study the clinical picture in our case series along with the published literature to discuss the pathogenesis and propose modified diagnostic criteria for recurrent painful ophthalmoplegic neuropathy. Methods We reported five cases diagnosed as ophthalmoplegic migraine/RPON in our medical centers and reviewed the published literature related to RPON from the Pubmed database between 2000 and 2020. In one of these cases, a multiplanar reformation was performed to look at the aberrant cranial nerve. Results The mean onset age for RPON was 22.1 years, and the oculomotor nerve was the most commonly involved cranial nerve (53.9%) in 165 reviewed patients. In most patients, ophthalmoplegia started within 1 week of the headache attack (95.7%, 67/70). Additionally, 27.6% (40/145) of patients presented enhancement of the involved nerve(s) from MRI tests. Finally, 78 patients received corticosteroids, out of which 96.2% benefited from them. Conclusion This is the first time multiplanar reformation has been performed to reveal the distortion of the oculomotor nerve. Modified diagnostic criteria are proposed. We hope to expand the current knowledge and increase the detection of recurrent painful ophthalmoplegic neuropathy in the future.