What’s new in MSK Imaging – December 2020

2 years ago

Superolateral Hoffa Fat Pad Edema and Patellofemoral Maltracking: Systematic Review and Meta-Analysis

Kim JH, Lee SK. Superolateral Hoffa Fat Pad Edema and Patellofemoral Maltracking: Systematic Review and Meta-Analysis. American Journal of Roentgenology. 2020 Jun 6:1-3.

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22263

Background: Superolateral Hoffa fat pad (SHFP) edema is a sign of an underlying syndrome characterized by anterior knee pain and tenderness in the lower pole of the patella in younger adults. It is caused by friction between the patellar tendon and the lateral femoral condyle, leading to edematous change in the SHFP by inflammatory reaction. MRI has shown an excellent ability to confirm this clinical diagnosis by observation of focal increased signal intensity on T2-weighted or proton density–weighted fat-saturated images of the SHFP between the patellar tendon and the lateral femoral condyle.

Questions: SHFP edema is well known to be associated with patellar maltracking and malalignment. The question is whether patients with SHFP edema are more symptomatic as compared to those without, both groups having other parameters associated with maltracking. Which imaging parameters of patellofemoral maltracking are associated with superolateral Hoffa fat pad (SHFP) edema?

Design: Systematic review and meta-analysis

Inclusion criteria: Studies were included if they met the criteria of comparing patients with and without SHFP edema and evaluating patellofemoral maltracking parameters on MRI.

Exclusion criteria: Studies were excluded if they were case reports or case series, review articles, guidelines, letters to the editor, systematic reviews or meta-analyses, or conference abstracts. They were also excluded if they did not clearly report patellofemoral maltracking parameters on MRI.

Method:  A systematic search of the MEDLINE, Embase, and Cochrane Library databases was performed to identify studies evaluating the relationship between SHFP edema and patellofemoral maltracking. Parameters for assessing patellofemoral maltracking on MRI were reviewed for each study. Two reviewers performed study selection, methodologic quality assessment, and data extraction.

Main Results:  Nine studies were eligible for inclusion in the present study. From the included studies, nine parameters assessing patellofemoral maltracking were analyzed: lateral patellofemoral angle, patellar tilt, patellar lateralization, trochlear depth, sulcus depth, sulcus angle, lateral trochlear inclination, distance between the tibial tuberosity and trochlear groove, and the Insall-Salvati ratio. Patients with SHFP edema had greater patellar tilt, greater patellar lateralization, greater distance between the tibial tuberosity and trochlear groove, and higher Insall-Salvati ratio than patients without SHFP edema.

Conclusion:  Patellofemoral maltracking imaging parameters, such as a more laterally displaced patella, greater TTTG distance, and patella alta, are correlated with SHFP edema.

Commentary: SHFP edema is patho-anatomic finding and is observed at the site of superolateral patellofemoral impingement. However, correlation with pain or restricted range of motion is challenging to assess. Congratulations for a nice work in summarizing the association of SHFP edema with patellofemoral malalignment measures.

Trainee take home message:

Anterior knee pain is a common, but challenging presenting scenario. One of the key causes is patellar maltracking.

Superolateral fat pad edema is a secondary indicator of maltracking.

Factors to focus on are:

  • Laterally displaced patella
  • Greater TT TG distance
  • Patella alta

 

Quantitative Variable Assessment of Patellar Instability: An MRI-Based Study

Friedman MV, Hillen TJ, Misra S, Hildebolt CF, Rubin DA. Quantitative Variable Assessment of Patellar Instability: An MRI-Based Study. American Journal of Roentgenology. 2020 Sep 9:1-8.

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22556

Background: Trochlear dysplasia, lateralization of the tibial tuberosity, and high position of the patella have been identified as the most important factors predisposing patients to patellar instability. Accurate assessment and characterization of these varying factors aid in directing patient management, with trochlear dysplasia considered one of the most important anatomic factors.

Questions: Can the three MRI parameters for patellar instability – TT-PCL, TT-TG, and trochlear dysplasia be reliably measured with reproducibility? Do they measure anatomic predisposition to patellar instability individually or in combination with the other parameters?

Design: Retrospective study.

Participants:  Study population was composed of 43 women and 57 men (mean age, 21.7 years; range, 13–50 years) who received both a clinical and an MRI diagnosis of a patellar dislocation event at a single institution from 2013 to 2015.

Inclusion criteria:  Patients who received both a clinical and an MRI diagnosis of a patellar dislocation event. Clinical examination revealed positive apprehension test results, excessive patellar quadrant translation, joint effusion, and a lack of positive cruciate and meniscal examination findings.

Exclusion criteria:  History of a patellar instability event, prior knee surgery, or concurrent cruciate or collateral ligamentous injury at the time of patellar dislocation event resulting in joint instability that might affect the desired measurements.

Methods: 100 patients diagnosed with a patellar dislocation injury and 100 age- and sex-matched control patients were examined using MRI. The distance between the tibial tubercle and posterior cruciate ligament (TT-PCL), distance between the tibial tubercle and trochlear groove (TT-TG), and TG depth (trochlear dysplasia) were measured independently by three fellowship-trained musculoskeletal radiologists. Intraclass correlation coefficient (ICC) was used to assess intraobserver and interobserver reliability. The parameters in both groups were tested for interdependence on each other and were compared for prevalence and association with patellar instability.

Main results: All three parameters showed almost perfect intra-observer and interobserver reliability and were significantly more common in the patellar instability group. Trochlear dysplasia had the highest association with patellar instability, both as a unique parameter and in pairwise combination with an abnormal TT-TG. Optimal cutoff thresholds for normal TT-TG and TT-PCL were 15.00 mm or less and 21.30 mm or less, respectively. The optimal normal cutoff threshold for evaluating trochlear dysplasia via trochlear depth was 4.95 mm or more.

Conclusion: TT-PCL, TT-TG, and trochlear dysplasia measurements can be reliably evaluated on MRI with almost perfect intra and interobserver reliability. The normal cutoff thresholds of both TT-TG (≤ 15.00 mm) and TT-PCL (≤ 21.30 mm) on MRI can be lowered. The study confirmed 5 mm or greater as a normal cutoff threshold when evaluating trochlear dysplasia via trochlear depth. Finally, the prevalence of TT lateralization and trochlear dysplasia is significantly higher in the patellar instability population, and trochlear dysplasia is the most important factor in the development of patellar instability.

Commentary: Great work! Congratulations. Observational or retrospective studies cannot however be used to demonstrate causation. Association would be a better term. Hopefully, surgeons will pay more attention towards trochleoplasty in the setting of patellofemoral malalignment/tracking, a less commonly performed procedure in North America.

Trainee take home messages:

  • Patients with patellar instability are apprehensive on clinical exam, when you mobilize their patella.
  • Trochlear dysplasia is the primary cause for patellar instability.
  • Look for trochlear depth as an indicator of dysplasia.

 

Use of Advanced Imaging for Radiographically Occult Hip Fracture in Elderly Patients: A Systematic Review and Meta-Analysis

Haj-Mirzaian A, Eng J, Khorasani R, Raja AS, Levin AS, Smith SE, Johnson PT, Demehri S. Use of Advanced Imaging for Radiographically Occult Hip Fracture in Elderly Patients: A Systematic Review and Meta-Analysis. Radiology. 2020 Jul 7:192167.

https://pubs.rsna.org/doi/abs/10.1148/radiol.2020192167

Background: The overall rate of hip fractures not identified on radiographs but that require surgery (ie, surgical hip fractures) remains unclear in elderly patients who are suspected to have such fractures based on clinical findings. Surgical hip fractures were defined as fractures that required immediate surgical intervention and included femoral head, femoral neck, intertrochanteric, or subtrochanteric fractures. Moreover, the importance of advanced imaging in these patients has not been comprehensively assessed.

Questions: What is the frequency of radiographically occult hip fracture in elderly patients?  Is there a higher-risk subpopulation? Is CT and bone scanning as effective as MRI in the detection of occult fractures?

Design: Meta-analysis

Participants: Thirty-five studies were identified (2992 patients; mean age, 76.8 years ± 6.0 [standard deviation]; 66% female).

Inclusion criteria: Studies were included if patients were clinically suspected to have hip fracture but there was no radiographic evidence of surgical hip fracture (including absence of any definite fracture or only presence of isolated greater trochanter [GT] fracture).

Exclusion criteria: Studies assessing patients not clinically suspected of having hip fracture, non- English publications, case reports, case series, review, opinion/editorial, animal study

Methods: A literature search was performed to identify English-language observational studies published from inception to September 27, 2018. The rate of surgical hip fracture was reported in each study in which MRI was used as the reference standard. The pooled rate of occult fracture, diagnostic performance of CT and bone scanning, and strength of evidence (SOE) were assessed.

Main Results:

1) The frequency of radiographically occult hip fractures is high (range, 39%–92%) in patients aged 56–82 years who are clinically suspected to have hip fracture.

2) Patients have a higher probability of occult hip fracture if they have radiographic evidence of isolated greater trochanter fracture (relative risk, 2.4), are at least 80 years old (relative risk, 1.3), have equivocal radiographic reports (relative risk, 1.6), and have a clear history of recent trauma (relative risk, 1.5).

3) CT and bone scanning are less sensitive for occult hip fractures (sensitivity, 79% and 87%, respectively) compared with MRI.

Conclusion: Elderly patients with acute hip pain and negative or equivocal findings at initial radiography have a high frequency of occult hip fractures. Therefore, the performance of advanced imaging (preferably MRI) may be clinically appropriate in all such patients.

Commentary: Congratulations for your publication. The analysis proves utility of MRI in hip fractures, a well-known fact. However, one should assess newer technology- thin slice CT, DECT with bone marrow edema map, etc.- much easier to do in ER as compare to MRIs.

Trainee take home messages:

  • Occult hip fracture on radiographs is a common problem with catastrophic results, when missed.
  • With appropriate clinical history in the elderly, do not hesitate to perform advanced imaging – MRI, as it clearly changes management.
  • Limited MRI – Coronal STIR and Coronal T1 pelvic sequences are adequate for evaluation.

 

Diagnostic Accuracy of Limited MRI Protocols for Detecting Radiographically Occult Hip Fractures: A Systematic Review and Meta-Analysis

Wilson MP, Nobbee D, Murad MH, Dhillon S, McInnes MD, Katlariwala P, Low G. Diagnostic accuracy of limited MRI protocols for detecting radiographically occult hip fractures: a systematic review and meta-analysis. American Journal of Roentgenology. 2020:1-9.

https://www.ajronline.org/doi/full/10.2214/AJR.19.22676

Background: The primary objective of this systematic review and meta-analysis was to evaluate the diagnostic accuracy of limited MRI protocols for detecting radiographically occult proximal femoral fractures compared with a multiparametric MRI protocol with or without clinical outcome as the reference standard. Principal secondary objectives included evaluating the diagnostic accuracy of single-plane T1-weighted, STIR, T1-weighted and STIR, and T2-weighted protocols for the detection of radiographically occult proximal femoral fractures.

Questions: What is the diagnostic accuracy of limited MRI protocols for detecting radiographically occult proximal femoral fractures?

Design: Systematic review and meta-analysis

Inclusion criteria: All original articles evaluating the diagnostic accuracy of a limited MRI protocol for detection of radiographically occult proximal femoral fractures in patients with acute hip pain after minor trauma compared with a multiparametric MRI protocol with or without clinical outcome as the reference standard were evaluated with full-text review.

Exclusion criteria: Studies were excluded from the analysis if only pediatric patients younger than 18 years old were evaluated, fewer than 10 patients were included, a patient population other than patients with acute hip pain after trauma was used, fractures that were not radio-graphically occult were included, a limited MRI protocol was not the index test, multiparametric MRI was not the reference standard, or there was insufficient information available to reconstruct a 2 × 2 contingency table after attempted e-mail correspondence with the author or authors. In addition, nonoriginal articles including review articles, guidelines, consensus statements, letters, and editorials were excluded.

Method: Original articles with 10 or more patients evaluating limited MRI protocols for the diagnosis of radiographically occult proximal femoral fractures compared with multiparametric MRI with or without clinical outcome as the reference standard were included in the analysis. Patient, clinical, MRI, and performance parameters were independently acquired by two reviewers. Meta-analysis was performed using a bivariate mixed-effects regression model.

Main Results:  Five studies were included in the meta-analysis.

  1. The pooled and weighted summary sensitivity and specificity and the area under the summary ROC curve for limited MRI protocols in detecting radiographically occult hip fractures were 99%, 99%, and 1, respectively.
  2. The aggregate sensitivity and specificity values for a single-plane T1-weighted sequence only, STIR sequence only, T1-weighted and STIR sequences, and T2-weighted sequence only were as follows: 97% and 100%, 99% and 99%, 100% and 99%, and 86% and 97%, respectively.
  3. Sensitivity was 100% when images were acquired on 3-T scanners only and 99% when interpreted only by certified radiologists. The mean scanning time for the limited MRI protocols was less than 5 minutes.

Conclusion: Limited MRI protocols can be used as the standard of care in patients with a suspected but radiographically occult hip fracture. A protocol composed of coronal T1-weighted and STIR sequences is 100% sensitive.

Commentary: Thanks for your work. Limited MRI should be used more frequently from the ED, when evaluating patients, particularly elderly patients with complaints of acute hip pain or when they are non weight bearing, and X-rays are normal. The analysis again proves utility of MRI in hip fractures, a well-known fact. However, one should assess newer technology- thin slice CT, DECT with bone marrow edema map, etc.- much easier to do in ER as compare to MRIs.

Trainee take home messages:

  • MRI is excellent for diagnosing occult hip fracture.
  • Short sequence MRI of less than 5 minutes can diagnose majority of occult fractures.

 

Dual-Energy CT for Suspected Radiographically Negative Wrist Fractures: A Prospective Diagnostic Test Accuracy Study

Müller FC, Gosvig KK, Børgesen H, Gade JS, Brejnebøl M, Rodell A, Nèmery M, Boesen M. Dual-energy CT for suspected radiographically negative wrist fractures: a prospective diagnostic test accuracy study. Radiology. 2020 Jul 14:192701.

https://pubs.rsna.org/doi/abs/10.1148/radiol.2020192701

Background: Patients with wrist trauma and negative findings on radiographs often undergo additional MRI examinations to assess for radiographically occult fractures. Dual-energy CT may be more readily available than MRI in some settings. The purpose of this study is to evaluate the diagnostic test accuracy of dual-energy CT in helping detect bone marrow edema and fracture in participants with wrist trauma and clinical suspicion of a wrist fracture but with negative findings on radiographs.

Questions: How effective is Dual-energy CT in the detection of bone marrow edema and fractures of the wrist in patients with clinical suspicion of a wrist fracture and negative findings on radiographs?

Design: Prospective study

Participants: Adults were prospectively enrolled between January 2018 and November 2018. Seven hundred fifty bones in 50 wrists of 46 patients (four patients had bilateral trauma) were therefore included in the analysis.

Inclusion criteria: Adults (≥18 years) with wrist trauma referred for MRI were eligible if they had a relevant trauma history and negative or inconclusive findings on radiographs but a clinical suspicion of fracture. Participants with visible fractures who were referred for MRI with a suspicion of additional fractures not visible on radiographs were also eligible.

Exclusion criteria: Contraindications to MRI, pregnancy, prior surgery or metal implants at the wrist of interest, or inability to raise the arm above the head.

Methods: Wrists were examined with dual-energy CT and MRI, and images were read by four readers who were blinded to clinical information. The presence of bone marrow edema and fracture was rated per bone. The reference standard for bone marrow edema was the combined reading of MRI scans. The reference standard for fracture was a combined reading of MRI and dual-energy CT scans. A fifth radiologist arbitrated results in case of discrepancies. Diagnostic test accuracy was calculated per reader and for readers combined using exact binomial tests.

Main Results:

1) Both MRI and dual-energy CT had a high sensitivity (80% vs 91%) and specificity (93% vs 87%) in helping detect radiographically negative wrist fractures.

2) Dual-energy CT had a sensitivity of 94% and a specificity of 65% in depicting wrists with traumatic bone marrow edema in patients with radiographically negative wrist fractures.

Conclusion: Dual-energy CT had a high sensitivity and a moderate specificity in the detection of bone marrow edema of the wrist. Dual-energy CT had high sensitivity and specificity in depicting fractures of the wrist in patients with suspected wrist fractures and negative findings on radiographs.

Commentary: Thank you for your publication. Larger studies of extremity fractures are lacking in the DECT literature. Comparison of DECT and MRI is also excellent. In our experience, when the patient is casted, the bone marrow edema is not visible for some reason. That reduces the sensitivity of DECT.

Trainee take home messages:

  • Dual energy CT can help with identification of bone edema.
  • Availability of DECT is increasing in the ED and is a rapid solution for detection of occult wrist injuries to instigate appropriate treatment.

 

Predicting Bone Marrow Edema and Fracture Age in Vertebral Fragility Fractures Using MDCT

Chang MY, Lee SH, Ha JW, Park Y, Zhang HY, Lee SH. Predicting bone marrow edema and fracture age in vertebral fragility fractures using MDCT. American Journal of Roentgenology. 2020 Oct;215(4):970-7.

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22606

Background: A cortical or trabecular fracture line without bone destruction, diffuse vertebral sclerosis, and diffuse paravertebral soft-tissue change are known CT features of acute benign VCFs (vertebral compression fractures), although prior studies have mainly focused on the differentiation of benign and malignant VCFs rather than the presence or absence of bone marrow edema (BME). Radiographic indications of acute (< 2 months’ duration) compression fractures are presence of a step defect, presence of a soft-tissue hemorrhage, and a linear white band of condensation. These radiographic findings can also be estimated on CT images.

Questions: Can CT features predict bone marrow edema on MRI and fracture age in vertebral fragility fractures?

Design: Retrospective study

Participants: A total of 189 thoracolumbar compression fractures in 103 patients (14 men, 89 women; mean age, 76 years) imaged with both spine CT and MRI were retrospectively included.

Inclusion criteria: Patient records for patients who had diagnostic codes of thoracolumbar compression fracture but not malignancy were searched to find benign fragility compression fractures. Patients who had undergone both spine CT and spine MRI within 7 days were recruited.

Exclusion criteria:  Patients were excluded who had compression fracture resulting from high-energy trauma (motor vehicle accidents and falls from the height above patient’s stature), infection, a previous surgery that hindered proper analysis of bone marrow signal change by metal artifacts, images of poor quality, and pathologic compression with benign tumor (hemangioma).

Methods: The presence and extent of BME were assessed on MRI to divide fractures into those with and without BME. The group with BME was then classified for subgroup analysis into fractures with extensive BME (comprising 50% or more of the vertebral body) and those with BME comprising less than 50% of the vertebral body. On CT, five features (presence of cortical or endplate fracture line, presence of trabecular fracture line, presence of condensation band, change in trabecular attenuation, and width of paravertebral soft-tissue change) were analyzed.

Main Results: All five CT findings were predominantly seen in fractures with BME. Elevated trabecular attenuation, presence of a cortical or endplate fracture line, and paravertebral soft-tissue width showed excellent diagnostic indication for fractures with BME. In the subgroup with extensive BME, paravertebral soft-tissue width was significantly higher, whereas the change in trabecular attenuation was lower compared with those with BME comprising less than 50% of the vertebral body. When BME was present, fracture age was not significantly different between the two subgroups, and only greater trabecular attenuation elevation was predictive of older fracture age on linear mixed model analyses.

Conclusion: CT features accurately correlate with the presence and extent of BME in vertebral fragility fractures. Elevation of trabecular attenuation was the only significant image predictor of fracture age.

Commentary: Thanks for your publication. Sclerosis and increased density have been used to identify more subacute and chronic fracture. This work takes this knowledge forward and improves our understanding of fracture aging.

Trainee take home messages:

  • Age of vertebral fractures is challenging to predict.
  • Using bone marrow edema, sclerosis and density, it is possible to improve predictability of vertebral fracture age.

 

Quantitative Magnetic Resonance Imaging UTE-T2* Mapping of Tendon Healing After Arthroscopic Rotator Cuff Repair: A Longitudinal Study

Xie Y, Liu S, Qu J, Wu P, Tao H, Chen S. Quantitative Magnetic Resonance Imaging UTE-T2* Mapping of Tendon Healing After Arthroscopic Rotator Cuff Repair: A Longitudinal Study. The American Journal of Sports Medicine. 2020 Aug 19:0363546520946772.

https://journals.sagepub.com/doi/abs/10.1177/0363546520946772

Background: Ultrashort echo time–T2* (UTE-T2*) mapping sequence is acquired using different echo times in the short and ultrashort echo time range, which makes it possible to detect the detailed ultrastructure and further quantify short T2/T2* structures (eg, tendon). The UTE-T2* mapping technique has been applied to explore biochemical alteration of tendons. During the proliferative and remodeling phases of rotator cuff healing, disorganized collagen scar tissue at the healing site is initially produced. Subsequently, collagen fibers begin to deposit, orient, and rearrange. UTE-T2* values have been shown to be sensitive to these biochemical collagen matrix changes.

Questions: To evaluate and characterize the healing process of the repaired rotator cuff based on longitudinal changes in UTE-T2* values, clinical outcomes, and repair status in patients after arthroscopic rotator cuff repair (ARCR).

Design: Cohort study

Participants: A consecutive series of patients (n = 25) with supraspinatus tendon tear who were scheduled to undergo unilateral ARCR at the sports medicine department between 2015 and 2017. All lesions were confirmed using arthroscopy. A group of age-matched volunteers (n = 15) were recruited as healthy controls.

Inclusion criteria:

ARCR group –

(1) Small to large supraspinatus tendon tear (≥1 cm to <5 cm) according to the criteria established by DeOrio and Cofield

(2) Body mass index <30 kg/m2; and

(3) Symptom duration before surgery of <12 months.

Exclusion criteria:

(1) Grade 3 or 4 fatty degeneration in RC muscles according to Goutallier classification

(2) Moderate to severe glenohumeral arthritis; and

(3) Neuromuscular disease, rheumatoid arthritis, trauma, or other systemic diseases (eg, diabetes, hypertension), MRI contraindication, such as claustrophobia.

Methods:

Patients with ARCR (n = 25) underwent quantitative MRI and clinical examinations at serial follow-up time points: 3, 6, 12, and 24 months postoperatively. Age-matched healthy controls (n = 15) were evaluated at 3 and 12 months after enrollment. Clinical scores included the Constant, American Shoulder and Elbow Surgeons, and Fudan University Shoulder score, and visual analog scale for pain. The MRI examination included UTE-T2*mapping. UTE-T2* maps were generated for T2* values at the healing site. Sugaya classification was adopted to evaluate the repair status. Longitudinal analyses of clinical outcomes, UTE-T2* changes, and Sugaya classification were conducted.

Results:

  1. The overall retear rate was 8% (2/25, all Sugaya type IV). All patients (including the ones with retear) achieved satisfactory outcomes at 12 months that lasted to 24 months on the basis of clinical scores.
  2. The mean UTE-T2* values at the healing site showed an increase from 3 to 6 months (P = .03) and then decreased to a level similar to that observed in age-matched healthy tendons at 12 months (P = .1).
  3. No significant differences were found between UTE-T2* values at 12 and 24 months (P = .6).
  4. UTE-T2* values at the healing site significantly varied with the repair status according to Sugaya classification (P < .05). Moreover, significant correlations were noted between clinical scores and UTE-T2* values at 6 months and 12 months.

Conclusion: This study indicated a healing-related relationship between clinical outcomes and quantitative UTE-T2* values, which highlights the potential of using UTE-T2* mapping to track the tendon-healing process noninvasively. Moreover, the repaired tendon was comparable to age-matched healthy controls at 12-month follow-up based on UTE-T2* values

Commentary: Thank you for your innovative work. Practical utility may not be there at this stage but helps our understanding of healing changes with tendon repair.

Trainee take home messages:

  • Return to activity is currently based on clinical exam post repair of a rotator cuff tendon injury
  • Objective means of evaluation is important.

UTE provides an avenue to evaluate the degree of healing. Watch this space, the techniques and interpretations are in the early phases.

 

Imaging of the degenerative spine using a sagittal T2-weighted DIXON turbo spin-echo sequence

Sollmann N, Mönch S, Riederer I, Zimmer C, Baum T, Kirschke JS. Imaging of the degenerative spine using a sagittal T2-weighted DIXON turbo spin-echo sequence. European Journal of Radiology. 2020 Aug 4:109204.

https://www.sciencedirect.com/science/article/abs/pii/S0720048X20303934

Background: To evaluate the diagnostic performance of a sagittal T2-weighted DIXON turbo spin-echo (TSE) sequence and to assess whether fat-only images could replace dedicated sagittal T1-weighted sequences for magnetic resonance imaging (MRI) of the degenerative spine.

Questions: Can T2-weighted DIXON sequence without separate T1-weighted sequence accurately detect common degenerative changes of the spine?

Design: Retrospective cross-sectional observational study

Participants: 35 patients (56.5 ± 19.8 years, 62.9 % males) with lumbar back pain (LBP) who underwent MRI of the lumbar spine including a sagittal T2-weighted DIXON sequence (acquisition time: 3:25 min) and T1-weighted sequence (acquisition time: 3:03 min) were included.

Inclusion criteria: Patients were only included in case that they had sagittal T2-weighted DIXON as well as non-contrast T1-weighted sequences available, covering the complete lumbar spine.

Exclusion criteria: 1) Age below 18 years, 2) motion artifacts in imaging data, 3) presence of any implants in the field of view (FOV), 4) previous surgery with instrumentation at the lumbar spine, 5) lumbar scoliosis, 6) history of a congenital disorder with structural aberrations manifest at the level of the lumbar spine (e.g. spina bifida, tethered cord), 7) diagnosis of a hematopoietic disease, and 8) presence of vertebral fractures, malignant bone lesions, or spondylodiscitic lesions.

Methods: Two image layouts (layout 1: fat-only AND water-only AND in-phase images of the DIXON sequence; layout 2: water-only AND in-phase images of the DIXON sequence AND T1-weighted images) were evaluated by two readers (R1 and R2) concerning degenerative changes including diagnostic confidence (1 – low, 2 – intermediate, and 3 – high) and signal changes of vertebral bone marrow (BM). Results were compared between readers and layouts.

Main Results:  No differences were observed in the number of detected pathologies on a segment-wise level, nor in the number of segments affected by degenerative changes when comparing evaluations of layout 1 and layout 2 for each reader. Diagnostic confidence was high without a statistically significant difference between the readings of both layouts.

Conclusions: In patients with LBP, MRI using a sagittal T2-weighted DIXON sequence and no separate T1-weighted sequence might be sufficient to accurately detect common degenerative changes with high diagnostic confidence. Sparing dedicated T1-weighted sequences can considerably reduce overall scan time.

Commentary: Thanks for your work. T2W Dixon has been routine in our practice as well for a long time. It shortens the imaging time and like spine, three plane T2 Dixon can replace all imaging sequences by providing marrow assessment and pathology assessment in the same setting.

Trainee take home messages:

  • Marrow evaluation is an essential component of MSK MRI.
  • Time on an MRI is crucial.
  • Multipoint Dixon imaging might provide solutions for skipping the T-1WI.

 

Influence of Acromial Morphologic Characteristics and Acromioclavicular Arthrosis on the Effect of Platelet-Rich Plasma on Partial Tears of the Supraspinatus Tendon

Berná-Mestre JD, Fernández C, Carbonell G, García A, García-Vidal JA, Mirapeix FM, Berná-Serna JD. Influence of Acromial Morphologic Characteristics and Acromioclavicular Arthrosis on the Effect of Platelet-Rich Plasma on Partial Tears of the Supraspinatus Tendon. American Journal of Roentgenology. 2020 Oct;215(4):954-62.

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22331

Background: The use of autologous platelet-rich plasma (PRP) has become widespread for treating tendon abnormalities. It is important that the infiltration be done with ultrasound (US) guidance to locate the tendon tear, insert the tip of the needle, and confirm in real time that the tendon tear is filled correctly with PRP. No previous studies have analyzed the effect of US-guided PRP infiltration on the size of the different types of partial SST tears (partial and full thickness) or on the subacromial-subdeltoid (SASD) bursitis associated with the tear.

Questions:  What are the medium term effects of ultrasound guided infiltration of platelet rich plasma on partial tears of supraspinatus tendon? What are the prognostic indicators of unfavorable outcome?

Design: Prospective study

Participants: Total of 128 patients were included in the analysis (66 men, 62 women; mean age, 48.3 years; range, 20–59 years)

Inclusion criteria: Age 20–60 years, partial SST tear diagnosed with MRI, and shoulder pain lasting more than 3 months.

Exclusion criteria: History of trauma, surgery, or instability of the shoulder; ingestion of nonsteroidal anti-inflammatory drugs (NSAIDs) or opiates; prior local infiltration of the shoulder; MRI more than 1 year previously; complete SST tear or partial tear measuring 1.5-cm or larger or located in the myotendinous junction; associated tendon or bone injuries; and evident glenohumeral arthrosis (clinically significant articular narrowing, subchondral involvement, or osteophytes larger than 2 mm) or inflammatory or crystal arthropathy.

Methods: Over a period of 4 years, patients with a partial SST tear smaller than 1.5 cm referred for ultrasound-guided PRP infiltration (1 mL) for shoulder pain lasting more than 3 months were recruited consecutively. MRI was used to analyze the type of acromion and presence of acromioclavicular (AC) arthrosis. Primary (size of the tear and associated bursitis) and secondary (mobility and pain) results were collected at 3 months.

Main Results: At 3 months, favorable evolution of the tear repair was recorded in 71.1% of patients and resolution of bursitis in 66.7%. Changes in tear size had large effect sizes, as did pain and shoulder mobility. The strongest predictors of unfavorable evolution of tear and bursitis were type 3 acromion and types 1 and 2 acromion with AC arthrosis.

Conclusion: With isolated partial SST tears smaller than 1.5 cm the presence of a type 3 acromion or severe AC arthrosis is predictive of unfavorable results, and acromioplasty must be contemplated, whereas in patients with type 1, 2, or 4 acromion with or without mild AC arthrosis, PRP therapy should be regarded as one of the first therapeutic options.

Commentary: Thanks for your work. Type 3 acromion is very rare in our experience, and mostly it’s located near the AC joint articulation and might represent osteophyte itself. Lack of comparison with other treatments e.g. simple steroid treatment or physiotherapy has been a major issue with PRP studies and evidence of its effect on rotator cuff repair (mostly fibrous filling) is weak at best.

Trainee take-home messages:

  • PRP is an option to treat partial-thickness rotator cuff tears.
  •  No robust evidence is available for outcome measures for such treatment.
  •  Mechanical challenges can occur due to acromion shape during ultrasound-guided injection of rotator cuff tears.

 

Optimal Choice of Ultrasound-Based Measurements for the Diagnosis of Ulnar Neuropathy at the Elbow: A Meta-Analysis of 1961 Examinations

Haj-Mirzaian A, Hafezi-Nejad N, Grande FD, Endo Y, Nwawka OK, Miller TT, Carrino JA. Optimal choice of ultrasound-based measurements for the diagnosis of ulnar neuropathy at the elbow: a meta-analysis of 1961 examinations. American Journal of Roentgenology. 2020 Nov;215(5):1171-83.

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22457

Background: Ulnar neuropathy at the elbow (UNE) is one of the most common peripheral entrapment neuropathies. In general, evidence suggests that US can be accurately used for the diagnosis of UNE. However, previous studies are highly heterogeneous regarding the US measurement techniques used and cutoff values; various measured parameters (diameter, cross-sectional area [CSA], ratio of ulnar nerve); measurement location (mid arm to wrist); and degree of elbow flexion during measurement.

Questions: What is the optimal ultrasound measurement technique and cut off value for the diagnosis of ulnar neuropathy in elbow?

Design: Meta-analysis

Participants:  19 studies (1961 examinations) were included.

Inclusion criteria: Studies evaluating the diagnostic accuracy of US of patients with ulnar neuropathy at the elbow before April 2019.

Methods: Random-effects modeling was performed to compare the sensitivity, specificity, and diagnostic odds ratio (DOR) of different US measurements, including diameter and cross-sectional area (CSA) of the nerve at the medial epicondyle or proximal and distal levels, maximal diameter, maximal CSA, and nerve ratios. Sensitivity and metaregression analyses were performed to assess the impact of clinical and imaging-based variables on the DOR of US.

Main results: Measuring the CSA of the ulnar nerve at the medial epicondyle with a cutoff value greater than 10–10.5 mm2 had higher sensitivity than other techniques. Nerve ratios had higher specificity than other measurements; however, the definition of ratios and cutoff values varied across studies. ROC analysis showed higher diagnostic performance for measuring CSA at the medial epicondyle. The mean CSA value was a significant predictor of the DOR of US. Every 1-mm2 larger CSA was associated with a 36% increase in DOR. The diagnostic performance of US was the same in any degree of elbow flexion.

Conclusion: Measuring CSA (not diameter) of the ulnar nerve, measuring at the level of the medial epicondyle (not proximal or distal levels), and using a cutoff value of 10–10.5 mm2 is recommended for the diagnosis of ulnar neuropathy. US measurements can be performed in any degree of elbow flexion. Maximal nerve diameter, maximal CSA, and nerve ratios cannot be considered optimal methods for the diagnosis of UNE.

Commentary: Congratulations for your publication. False negative electrophysiology and subclinical neuropathy with lack of overt symptoms represent major issues with respect to a reference standard for ulnar neuropathy. Nonetheless, this work assists in establishing the utility of ultrasound in UNE.  In author’s experience, another major role of US is in dynamic evaluation for ulnar nerve and triceps snapping syndromes, which is difficult to evaluate with MRI.

Trainee take-home messages:

  • The cross-sectional area of the ulnar nerve is an indicator of ulnar neuropathy.
  • Measure ulnar nerve at the medial epicondyle.
  • Cross-sectional area cut off value of 10-10.5mm2 is a good indicator of ulnar neuropathy.
References
  • Share