Variable echo time imaging for detecting the short T2* components of the sciatic nerve: a validation study.

OBJECTIVE: The aim of this study was to develop and validate an MRI protocol based on a variable echo time (vTE) sensitive to the short T2* components of the sciatic nerve. MATERIALS AND METHODS: 15 healthy subjects (M/F: 9/6; age: 21-62) were scanned at 3T targeting the sciatic nerve at the thigh bilaterally, using a dual echo variable echo time (vTE) sequence (based on a spoiled gradient echo acquisition) with echo times of 0.98/5.37 ms. Apparent T2* (aT2*) values of the sciatic nerves were calculated with a mono-exponential fit and used for data comparison. RESULTS: There were no significant differences in aT2* related to side, sex, age, and BMI, even though small differences for side were reported. Good-to-excellent repeatability and reproducibility were found for geometry of ROIs (Dice indices: intra-rater 0.68-0.7; inter-rater 0.70-0.72) and the related aT2* measures (intra-inter reader ICC 0.95-0.97; 0.66-0.85) from two different operators. Side-related signal-to-noise-ratio non-significant differences were reported, while contrast-to-noise-ratio measures were excellent both for side and echo. DISCUSSION: Our study introduces a novel MR sequence sensitive to the short T2* components of the sciatic nerve and may be used for the study of peripheral nerve disorders.

Role of MRI in predicting meniscal tear reparability.

OBJECTIVE: To elucidate the role of MRI in predicting meniscal tear reparability according to tear type and location in relation to vascular zones. MATERIALS AND METHODS: In this retrospective study, two readers evaluated 79 pre-surgical MRIs of meniscal tears arthroscopically treated with meniscectomy or meniscal repair. Tears were classified according to type into vertical, horizontal, radial, complex, flaps and bucket handle and were considered reparable if the distance measured from the tear to the menisco-capsular junction was less than or equal to 5 mm. Predictions were compared with the surgical procedure performed in arthroscopy. We assessed the diagnostic performance of MRI, agreement between MRI and arthroscopy, and interrater agreement. Then, we conducted an ROC analysis on the distances measured by the first reader and built a multivariate logistic regression model. RESULTS: MRI had a sensitivity, specificity, PPV, NPV and accuracy, respectively, of 85%, 79%, 86%, 76% and 83% in predicting meniscal tear reparability. Correct predictions for the specific tear pattern were 76% for vertical, 84% for horizontal, 88% for radial, 86% for complex, 84% for flaps and 86% for bucket handle. Agreement between the two readers' predictions and arthroscopy was good (k = 0.65 and 0.61, respectively). Inter-rater agreement was almost excellent (k = 0.79). The ROC analysis revealed sensitivity and specificity of 73% and 83% with a cutoff value of <4 mm (p < 0.001). Anterior cruciate ligament injury and medial meniscal tear increased the likelihood of meniscal tear reparability. CONCLUSIONS: MRI can be a reliable and accurate tool to predict the reparability of meniscal tears, with higher prediction rates for bucket-handle tears.

An optimized 1.5 Tesla MRI protocol of the brachial plexus.

PURPOSE: Creating an effective MRI protocol for examining the brachial plexus poses significant challenges, and despite the abundance of protocols in the literature, there is a lack of reference standards for basic sequences and essential parameters needed for replication. The aim of this study is to establish a reproducible 1.5 T brachial plexus imaging protocol, including patient positioning, coil selection, imaging planes, and essential sequence parameters. METHODS: We systematically investigated MRI sequences, testing each parameter through in vivo experiments, examining their effects on signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), visual quality scores, and acquisition time. Sequences were refined based on optimal quality and timing scores. The final protocol was tested on scanners from two other vendors for reliability. RESULTS: The final protocol included a combination of 2D turbo-spin-echo and 3D SPACE T1, SPACE STIR, and VIBE DIXON sequences. Recommendations for imaging planes, phase encoding, field of view, TR, TE, resolution, number of slices, slice thickness, fat and blood suppression, and acceleration strategies are provided. The protocol was successfully translated to other vendor's scanners with comparable quality. CONCLUSION: We present an optimized protocol detailing the essential parameters for reproducibility. Our comprehensive list of experiments describes the impact of each parameter on image quality and scan time, addressing common artifacts and potential solutions. This protocol can benefit both young radiologists new to the field and experienced professionals seeking to refine their existing protocols.

Ultrasound elastography in chronic kidney disease: a systematic review and meta-analysis.

Ultrasound elastography (USE) is a noninvasive technique for assessing tissue elasticity, and its application in nephrology has aroused growing interest in recent years. The purpose of this article is to systematically review the clinical application of USE in patients with chronic kidney disease (CKD), including native and transplanted kidneys, and quantitatively investigate differences in elasticity values between healthy individuals and CKD patients. Furthermore, we provide a qualitative analysis of the studies included, discussing the potential interplay between renal stiffness, estimated glomerular filtration rate, and fibrosis. In January 2022, a systematic search was carried out on the MEDLINE (PubMed) database, concerning studies on the application of USE in patients with CKD, including patients with transplanted kidneys. The results of the included studies were extracted by two independent researchers and presented mainly through a formal narrative summary. A meta-analysis of nine study parts from six studies was performed. A total of 647 studies were screened for eligibility and, after applying the exclusion and inclusion criteria, 69 studies were included, for a total of 6728 patients. The studies proved very heterogeneous in terms of design and results. The shear wave velocity difference of - 0.82 m/s (95% CI: - 1.72-0.07) between CKD patients and controls was not significant. This result agrees with the qualitative evaluation of included studies that found controversial results for the relationship between renal stiffness and glomerular filtration rate. On the contrary, a clear relationship seems to emerge between USE values and the degree of fibrosis. At present, due to the heterogeneity of results and technical challenges, large-scale application in the monitoring of CKD patients remains controversial.

Non-contrast MR dacryocystography for the evaluation of epiphora and recurrent dacryocystitis: A preliminary study.

INTRODUCTION: Obstruction of the lacrimal drainage represents a common ophthalmologic issue. The blockage may interest any level of the lacrimal drainage pathway, and it is important to find the site of obstruction to plan the most appropriate treatment. In this study, findings from magnetic resonance (MR) dacryocystography were compared with findings from endoscopic and surgical procedures to evaluate the accuracy of MR dacryocystography in localizing the site of nasolacrimal duct obstruction. METHODS: We enrolled twenty-one patients with clinical suspicion of nasolacrimal duct obstruction who underwent dacryoendoscopy and surgery. MR dacryocystography was performed with a heavily T2-weighted fast spin echo sequence in the coronal planes. Before the MRI was performed, a sterile 0.9% NaCl solution was administered into both conjunctival sacs. For each examination, two independent readers (with 8 and 10 years of experience in head and neck imaging) evaluated both heavily 3D space T2-weighted and STIR sequences. RESULTS: Stenosis/obstruction of nasolacrimal duct or lacrimal sac was diagnosed in all 21 patients who underwent MRI dacryocystography. In particular, the site of the obstruction was classified as lacrimal sac in 12 (57%) patients, nasolacrimal duct in 6 (29%) patients, and canaliculi in 3 (14%) patients by both readers. By comparison with the evidence resulting from the endoscopy, there were differences between MRI dacryocystography and dacryoendoscopy in the evaluation of the obstruction's site in three patients, with an overall accuracy of 85.7%. CONCLUSION: MR dacryocystography allows a non-invasive evaluation of the lacrimal drainage pathway, valid for the planning of the most appropriate treatment.

Texture analysis and machine learning to predict water T2 and fat fraction from non-quantitative MRI of thigh muscles in Facioscapulohumeral muscular dystrophy.

PURPOSE: Quantitative MRI (qMRI) plays a crucial role for assessing disease progression and treatment response in neuromuscular disorders, but the required MRI sequences are not routinely available in every center. The aim of this study was to predict qMRI values of water T2 (wT2) and fat fraction (FF) from conventional MRI, using texture analysis and machine learning. METHOD: Fourteen patients affected by Facioscapulohumeral muscular dystrophy were imaged at both thighs using conventional and quantitative MR sequences. Muscle FF and wT2 were calculated for each muscle of the thighs. Forty-seven texture features were extracted for each muscle on the images obtained with conventional MRI. Multiple machine learning regressors were trained to predict qMRI values from the texture analysis dataset. RESULTS: Eight machine learning methods (linear, ridge and lasso regression, tree, random forest (RF), generalized additive model (GAM), k-nearest-neighbor (kNN) and support vector machine (SVM) provided mean absolute errors ranging from 0.110 to 0.133 for FF and 0.068 to 0.115 for wT2. The most accurate methods were RF, SVM and kNN to predict FF, and tree, RF and kNN to predict wT2. CONCLUSION: This study demonstrates that it is possible to estimate with good accuracy qMRI parameters starting from texture analysis of conventional MRI.

Laparoscopic subtotal colectomy for synchronous colon high-grade dysplasia adenomas in intestinal malrotation: A case report and literature review.

Intestinal malrotation is an embryologic anomaly rarely presenting in adults especially in association with colon cancer. Fully laparoscopic colonic resection has not yet described in literature for adenomas in malrotation. Preoperative assessment of vascular anatomy by computed tomography is considered mandatory to perform safely laparoscopic surgery.

MR microneurography and quantitative T2 and DP measurements of the distal tibial nerve in CIDP.

OBJECTIVE: In this study we investigated the potential of magnetic resonance (MR) micro-neurography to detect morphological and relaxometric changes in distal tibial nerves in patients affected with chronic inflammatory demyelinating polyneuropathy (CIDP), and their associations with clinical and electrophysiological features. MATERIALS AND METHODS: 10 subjects affected with CIDP and 10 healthy subjects were examined. Multiple MR parameters, including the number of fascicles (N), fascicles diameter (FD), total fascicles area (FA), epineurium area (EA), total nerve area (NA), fascicles to nerve ratio (FNR) and quantitative T2 and proton density (PD) were investigated on high resolution MR images of the distal tibial nerve. Those parameters were correlated with clinical scores, age of onset, disease duration and electrophysiologic data. RESULTS: Median NA and FA were significantly increased in the CIDP population (median values for NA in cm2 in CIDP: 0.185; controls: 0.135; p: 0.028; for FA in CIDP 0.136; controls 0.094; p: 0.021). There was no correlation between the parameters investigated and clinical or electrophysiologic features. CONCLUSION: MR microneurography can detect increased total nerve and fascicle area in distal tibial nerves in CIDP and may be useful for diagnosing CIDP.

Diffusion-weighted imaging and loco-regional N staging of patients with colorectal liver metastases.

INTRODUCTION: Diffusion-weighted MRI (DWI) contributes to N staging of rectal cancers and diagnosis of colorectal liver metastases (CLM). About 15% of CLM patients have loco-regional lymph node (LN) metastases that impact prognosis and treatment strategy. This retrospective study is the first one to evaluate quantitative ADC measurement as a tool to identify metastatic LNs in patients with liver metastases from colorectal cancer. METHODS: All consecutive patients undergoing surgery for CLM between 2008 and 2015 were considered. Inclusion criteria were: intraoperative retrieval of at least one LN; LN ≥ 5 mm; DWI performed ≤2 months before surgery. The ADC and ADCratio (ADCLN/ADCCLM) were computed by two radiologists for all the LNs. RESULTS: Among 555 patients operated for CLM, 32 met the inclusion criteria. Fifty-six LNs were analyzed and 28 were metastatic. ADC and ADCratio in metastatic LNs were lower than in benign LNs (ADC = 1.37 vs. 1.83 × 10-3 mm2/s, p < 0.001; ADCratio = 1.26 vs. 1.73, p < 0.001). The optimal cut-off value for ADC was 1.48 x 10-3 mm2/s (AUC = 0.85, p < 0.001, sensitivity/specificity/accuracy 79%/93%/86% in per LN-analysis and 94%/86%/91% in per-patient analysis). The optimal cut-off for ADCratio was 1.15 (AUC = 0.80, p < 0.001, sensitivity/specificity/accuracy 69%/93%/81% and 76%,93%/84%). Excellent inter- and intra-operators' agreements were observed. CONCLUSION: In patients with CLM, ADC values < 1.48 x 10-3 mm2/s can be postulated as a cut-off to distinguish metastatic LNs.

Refining the management of patients with hepatocellular carcinoma integrating 11C-choline PET/CT scan into the multidisciplinary team discussion.

OBJECTIVE: The aim of this study was to report the impact of C-choline PET/CT on the management of patients with hepatocellular carcinoma (HCC) and incorporate into a refined algorithm combining diagnostic imaging and multidisciplinary team (MDT) discussion. PATIENTS AND METHODS: From February 2010 to February 2016, the charts of all patients discussed in the liver MDT were revised. Suspected or confirmed HCC lesions or Barcelona Clinic Liver Cancer stages A, B or C with a C-choline PET/CT performed in our hospital were included in the analyses. Overall, 73 patients (male : female=59 : 14; median age: 75 years) were enrolled. Forty-two (57%) patients were newly diagnosed, whereas 31 (43%) came to our attention at disease recurrence. Seven (10%) patients were Barcelona Clinic Liver Cancer stage 0, 31 (42%) patients were stage A, 15 (20%) patients were stage B, and 18 (25%) patients were stage C. The reference standards for ultimate imaging validation were either histology or MDT consensus. A minimum follow-up of 6 months was established. RESULTS: Overall eight (10%) patients were initially referred for chemotherapy (sorafenib), 43 (59%) for surgery, two (3%) for surgery or transarterial embolization, five (7%) for follow-up only, one (1%) for extrahepatic radiotherapy, seven (10%) for stereotactic body radiation therapy of the liver, six (8%) for transarterial embolization, and one (1%) for liver transplant. After C-choline PET/CT and MDT discussion, in seven patients the diagnosis changed, in six patients the treatment was changed, and in nine patients both the diagnosis and the treatment were changed. Overall, in 30% of our patients, the diagnosis or treatment was altered on the basis of our algorithm of management. CONCLUSION: The incorporation of C-choline PET/CT into the MDT discussion altered the diagnosis/treatment of one-third of HCC patients. We propose a novel diagnostic algorithm to be refined in referral centers for HCC management.

Median nerve evaluation by shear wave elastosonography: impact of "bone-proximity" hardening artifacts and inter-observer agreement.

PURPOSE: Peripheral nerves frequently travel close to the bone surface and are, therefore, prone to elastosonographic "bone-proximity" hardening artifacts. The impact of these artifacts on quantitative measurements of median nerve stiffness performed by shear wave elastosonography has not been explored. Our aim was to assess normal median nerve stiffness values at various locations. MATERIALS AND METHODS: Thirty-six healthy volunteers (24 women and 12 men) aged between 25 and 40 years were evaluated. Two operators performed the evaluation: one expert (6 years of ultrasound experience) and one inexperienced operator (6 months' experience). The nerve was sampled in cross-section at three different locations: mid-forearm, immediately before the carpal tunnel and within the tunnel. The ultrasound scanner was equipped with a 14-MHz linear probe. The Shear Wave module was activated in one-shot mode. Measurements were performed using a ROI corresponding to the diameter of the nerve. RESULTS: The mean values of stiffness of the medial nerve were 32.26 kPa ± 18.60 within the carpal tunnel, 22.20 kPa ± 9.84 at the carpal tunnel inlet and 7.62 kPa ± 7.38 in the forearm. Inter-observer agreement assessed using the intraclass correlation coefficient (ICC) was "moderate" within the carpal tunnel (ICC = 0.44), "moderate" at the carpal tunnel inlet (ICC = 0.41) and "fair" in the forearm (ICC = 0.38). CONCLUSIONS: The stiffness of the median nerve progressively increases in its distal portions, where the nerve approaches the bone surface. Inter-observer agreement was generally good (from fair to moderate).

Nerve Fascicles and Epineurium Volume Segmentation of Peripheral Nerve Using Magnetic Resonance Micro-neurography.

RATIONALE AND OBJECTIVES: The aims of this study were to propose a semiautomated technique to segment and measure the volume of different nerve components of the tibial nerve, such as the nerve fascicles and the epineurium, based on magnetic resonance microneurography and a segmentation tool derived from brain imaging; and to assess the reliability of this method by measuring interobserver and intraobserver agreement. MATERIALS AND METHODS: The tibial nerve of 20 healthy volunteers (age range = 23-69; mean = 47; standard deviation = 15) was investigated at the ankle level. High-resolution images were obtained through tailored microneurographic sequences, covering 28 mm of nerve length. Two operators manually segmented the nerve using the in-phase image. This region of interest was used to mask the nerve in the water image, and two-class segmentation was performed to measure the fascicular volume, epineurial volume, nerve volume, and fascicular to nerve volume ratio (FNR). Interobserver and intraobserver agreements were calculated. RESULTS: The nerve structure was clearly visualized with distinction of the fascicles and the epineurium. Segmentation provided absolute volumes for nerve volume, fascicular volume, and epineurial volume. The mean FNR resulted in 0.69 with a standard deviation of 0.04 and appeared to be not correlated with age and sex. Interobserver and intraobserver agreements were excellent with alpha values >0.9 for each parameter investigated, with measurements free of systematic errors at the Bland-Altman analysis. CONCLUSIONS: We concluded that the method is reproducible and the parameter FNR is a novel feature that may help in the diagnosis of neuropathies detecting changes in volume of the fascicles or the epineurium.

In Vivo MR Microneurography of the Tibial and Common Peroneal Nerves.

MR microneurography is a noninvasive technique that provides visualization of the microanatomy of peripheral nerves, otherwise available only with histopathology. The objective of this study was to present a protocol to visualize the microstructure of peripheral nerves in vivo, using a 3T MRI scanner with a clinical set of coils and sequences. The tibial and the common peroneal nerves of healthy volunteers were imaged above the medial malleolus and at the level of the fibular head, respectively. The acquired images provided details about the internal structure of peripheral nerves, with visualization of the fascicles, the interfascicular fat, the epineurium, and the perineurium. MR microneurography can be performed in a clinical setting with acceptable imaging times and can be a potentially powerful tool that complements standard MR neurography.