What’s New in MSK Imaging? – March 2023

1 year ago

CT-Guided Core Needle Biopsy of Nonspinal Bone Lesions: Comparison of Occult and Visible Bone Lesions

Wonsuk Kim, MD, Kevin Sun, MD, Justin W. Kung, MD and Jim S. Wu, MD

American Journal of Roentgenology


Background:  CT guidance may be used for biopsy of indeterminate bone lesions detected by MRI or PET/CT that are not visible (i.e., occult) on CT owing to equipment-, patient-, and operator-related factors.

Questions:  What is the diagnostic yield (DY) and diagnostic performance of CT-guided core needle biopsy (CNB) of occult nonspinal bone lesion? What are the most common benign and malignant diagnoses for occult lesions undergoing CT-guided core needle biopsy (CNB)?

Design: Retrospective study

Participants: 1033 adult patients who underwent CT-guided non-spinal bone CNB between January 2004 and December 2020 were included.  The sample included 70 patients with occult lesions (mean age, 56.8 years; 38 women, 32 men) and 963 patients with visible lesions (mean age, 59.6 years; 475 women, 488 men).

Methods:   Lesions were classified as occult or visible on CT; biopsies of occult lesions were performed by targeting anatomic landmarks using prebiopsy MRI or PET/CT. Pathologic results of CNB were classified as diagnostic or nondiagnostic to calculate DY of CNB. For nondiagnostic CNBs, final diagnoses were established by subsequent pathologic, clinical, and imaging follow-up.

Fig. 4A —62-year-old woman with lymphoma and colon cancer who presented for oncology surveillance. A, Axial image from FDG PET/CT shows increased FDG avidity (arrow) in proximal humerus. B, Sagittal T1-weighted MR image shows overall hypointensity of lesion (arrowhead), though mild hyperintensity relative to skeletal muscle, suggestive of red marrow. Lesion was occult on CT at time of biopsy. C, Axial CT image from core needle biopsy shows biopsy needle in lesion, which was targeted according to anatomic landmarks with respect to prior imaging. Pathologic report described mildly hypercellular marrow with maturing trilineage hematopoiesis but no malignancy.

Main Results:

  1. Malignancy rate was lower for occult than for visible lesions. DY was lower for occult than for visible lesions. Diagnostic performance for detecting malignancy on the basis of final diagnoses was lower for occult than for visible lesions in terms of sensitivity, specificity, and accuracy.
  2. Final diagnoses among malignant occult and visible lesions included metastasis (frequencies of 63.3% vs 65.4%), leukemia/lymphoma (33.3% vs 11.6%), and myeloma (3.3% vs 10.4%); final diagnoses among benign occult and visible lesions included red marrow (34.2% vs 8.2%), reactive marrow (26.3% vs 11.8%), and fracture (18.4% vs 3.8%).
  3. Occult lesions detected by MRI versus PET/CT had lower malignancy rate (39.3% vs 68.0%, p = .03) and lower DY (30.4% vs 60.0%, p = .01).

Conclusion: At CT-guided CNB, malignancy rate and DY are lower for occult than for visible lesions. Leukemia/lymphoma and red marrow are more common among occult than visible lesions. Understanding these characteristics can help guide radiologists’, referring providers’, and patients’ expectations when CNB of occult bone lesions is requested and performed.

Teaching point: It is not uncommon to mistake red marrow as a lesion, and one must always compare the marrow with the adjacent skeletal muscle. The results of this study are for most part expected- i.e. lower rate of malignancy and diagnostic yield for occult lesions. However, one must remember that it is not uncommon for occult lesions on CT to be malignant based on MR or PET/CT.


Degree of Accuracy with Which Deep Learning for Ultrasound Images Identifies Osteochondritis Dissecans of the Humeral Capitellum

Issei Shinohara, MD, Tomoya Yoshikawa, MD, Atsuyuki Inui, MD, Yutaka Mifune, MD, PhD, Hanako Nishimoto, MD, PhD, Shintaro Mukohara, MD, PhD, Tatsuo Kato, MD, Takahiro Furukawa, MD, Shuya Tanaka, MD, Masaya Kusunose, MD,  Yuichi Hoshino, MD, PhD, Takehiko Matsushita, MD, and Ryosuke Kuroda, MD, PhD

American Journal of Sports Medicine


Background: Medical screening using ultrasonography (US) has been performed on young baseball players for early detection of osteochondritis dissecans (OCD) of the humeral capitellum. Deep learning (DL) and artificial intelligence (AI) techniques are widely adopted in the medical imaging research field.

Questions: What is the diagnostic accuracy using DL for US images of OCD? Would DL improve the prediction accuracy of OCD?

Design: Cohort study (Diagnosis); Level of evidence, 2.

Participants: A total of 40 elbows (mean age of patients, 12.1 years) that were suspected of having OCD at a medical checkup and later confirmed by radiographs and magnetic resonance imaging were included in the study.

Methods: The affected elbows were used as the OCD group and the contralateral elbows as the control group. From US videos, 100 images per elbow were captured from different angles, and 4000 images of the elbows were prepared for both groups. Of these, 80% were randomly selected by DL models and used as training data; the remaining were used as test data. Transfer learning was conducted using 3 pretrained DL models. The confusion matrix and the area under the receiver operating characteristic curve (AUC) were used to evaluate the model, and the visualization of the areas deemed important by the DL models was also performed. Furthermore, OCD regions were detected using an automatic image recognition model based on DL.

Random selection of images to be trained by artificial intelligence. (A) Images of healthy group (in light blue) and osteochondritis dissecans (OCD) group (in orange) are randomly trained using a pretrained network. (B) Example control image. (C) Example OCD image. Images of OCD group show wall irregularity of humeral capitellum (red arrows).

Main Results: Classification of the OCD image by the DL model was performed; the best accuracy score was 0.87; the recall was 1.00. AUC was high for all DL models. Visualization of important features showed that AI predicted the presence of OCD by focusing on the irregularity or discontinuity of the surface of subchondral bone. In the detection of OCD task, the mean average precision was 0.83.

Conclusion: The DL on US images identified OCD with high accuracy. The important features detected by the DL models correspond to the areas used by clinicians in screening the US images. The OCD was also detected with high accuracy using the object detection model. The AI model may be used in medical screening for OCD.

Teaching point:  Excellent work- this paper again shows that AI can help detect small abnormalities with high accuracy.

Quantitative MRI Biomarkers to Predict Risk of Reinjury Within 2 Years After Bridge-Enhanced ACL Restoration

Dominique A. Barnes, BS , Gary J. Badger, MS, Yi-Meng Yen, MD, PhD, Lyle J. Micheli, MD, Dennis E. Kramer, MD, Paul D. Fadale, MD, Michael J. Hulstyn, MD, Brett D. Owens, MD, The BEAR Trial Team, Sean W. Flannery, PhD, Kirsten Ecklund, MS, Ryan M. Sanborn, BA, Meggin Q. Costa, BA, Cynthia Chrostek, BS, Benedikt L. Proffen, MD, Nicholas Sant, BS, Martha M. Murray, MD, Braden C. Fleming, PhD, and Ata M. Kiapour, PhD

American Journal of Sports Medicine



Background: Bridge-enhanced ACL restoration (BEAR), is a surgical procedure that stimulates ACL healing by placing an extracellular matrix–based implant within the injury site and using it to hold the patient’s blood in the space between the torn ends of the ligament. The blood-collagen scaffold composite subsequently creates an environment that is biologically conducive to ligament healing. As the BEAR technique is relatively new, postoperative outcome measures that can predict risk factors for reinjury and subsequent revision surgery remain unknown in patients who undergo the BEAR procedure. Studies have determined that changes in qMRI parameters, such as signal intensity (SI), volume, and cross-sectional area (CSA) of the ligament or graft, can be used to determine the integrity of the healing structures, as these parameters have been shown to reflect the biomechanical and histologic properties of the healing tissues. Whether qMRI variables predict risk of reinjury is unknown.

Questions: Can qMRI measures at 6 to 9 months after bridge-enhanced ACL restoration (BEAR) predict the risk of revision surgery within 2 years of the index procedure?

Study Design:  Cohort study; Level of evidence, 2.

Participants:  Originally, 124 patients underwent ACL restoration as part of the BEAR I, BEAR II, and BEAR III prospective trials and had consented to undergo an MRI of the surgical knee 6 to 9 months after surgery. Only 1 participant was lost to follow-up, and 4 did not undergo MRI, leaving a total of 119 patients for this study.

Methods: qMRI techniques were used to determine the mean cross-sectional area; normalized signal intensity; and a qMRI-based predicted failure load, which was calculated using a prespecified equation based on cross-sectional area and normalized signal intensity. Patient-reported outcomes (International Knee Documentation Committee subjective score), clinical measures (hamstring strength, quadriceps strength, and side-to-side knee laxity), and functional outcomes (single-leg hop) were also measured at 6 to 9 months after surgery. Univariate and multivariable analyses were performed to determine the odds ratios (ORs) for revision surgery based on the qMRI and non-imaging variables. Patient age and medial posterior tibial slope values were included as covariates.

Main Results:

  1. In total, 119 patients (97%), with a median age of 17.6 years, underwent MRI between 6 and 9 months postoperatively. Sixteen of 119 patients (13%) required revision ACL surgery.
  2. In univariate analyses, higher International Knee Documentation Committee subjective score at 6 to 9 months postoperatively and lower qMRI-based predicted failure load were associated with increased risk of revision surgery.
  3. In the multivariable model, when adjusted for age and posterior tibial slope, the qMRI-based predicted failure load was the only significant predictor of revision surgery.

Conclusion: Quantitative MRI-based predicted failure load of the healing ACL was a significant predictor of the risk of revision within 2 years after BEAR surgery. The current findings highlight the potential utility of early qMRI in the postoperative management of patients undergoing the BEAR procedure.

Teaching point: It important to be aware of newer techniques to treat ACL tears. This study highlights the utility of quantitative MRI in evaluating for revision surgery. Quantitative MRIs are not done as part of routine clinical practice but could be used in the future with AI techniques.


Early Postoperative CT scan Provides Prognostic Data on Clinical Outcomes of Fresh Osteochondral Transplantation of the Knee

Pablo Eduardo Gelber, MD, PhD , Eduard Ramírez-Bermejo, MD, and Oscar Fariñas, MD

American Journal of Sports Medicine


Background: There is a lack of information regarding the ability of imaging studies to predict clinical outcomes after fresh osteochondral allograft (FOCA) transplantation of the knee.

Questions: How effective is computed tomography (CT) scans in predicting the clinical outcome of fresh osteochondral allograft (FOCA) transplantation using the assessment computed tomography osteochondral allograft (ACTOCA) score?

Design: Cohort study; Level of evidence, 3.

Participants: A total of 38 cases who underwent FOCA transplantation for osteochondral knee lesions at one institution between August 2017 and August 2019 were included.

Methods: All patients were followed up for a minimum of 2 years. CT scans performed 6 months after surgery were evaluated by a musculoskeletal radiologist using the ACTOCA scoring system. The radiologist was blinded to the patient’s medical history. Clinical outcomes were assessed preoperatively and at 12 and 30 months postoperatively using the International Knee Documentation Committee (IKDC) score, the Kujala score, the Tegner activity scale, and the Western Ontario Meniscal Evaluation Tool (WOMET) score.


Main Results: The ACTOCA score at 6 months after surgery showed a statistically significant correlation with clinical results at 12 and 30 months. The correlation was better at 30 months, showing a high negative correlation with the IKDC score (−0.663) and a moderate negative correlation with the Kujala, WOMET, and Tegner scores (−0.593; −0.547, and −0.593, respectively) (P < .001).

Conclusion: A statistically significant correlation between the mean ACTOCA score on CT scans at 6 months and the clinical results measured by the IKDC, Kujala, WOMET, and Tegner scores at 30 months confirmed the predictive value of the ACTOCA score for use in clinical practice.

Teaching points:  This is an excellent study demonstrating the utility of CT in evaluating the osteochondral transplant fragment incorporation in the native bone. It is often difficult to evaluate the transplanted fragment even on MRI, so the parameters used in this study might be useful in the future.

Advantages of CT Versus MRI for Preoperative Assessment of Osteochondritis Dissecans of the Capitellum

Sebastian A. Müller, MD, Julia A. Müller-Lebschi, MD, Ezekiel E. Shotts, MD, Jeffrey R. Bond, MD, Christin A. Tiegs-Heiden, MD, Mark S. Collins, MD, and Shawn W. O’Driscoll, PhD, MD

American Journal of Sports Medicine


Background:  Magnetic resonance imaging (MRI) is considered to be the gold standard for imaging of osteochondritis dissecans (OCD).

Questions: Is CT superior to MRI for imaging OCD of the capitellum?

Design: Cohort study (diagnosis); Level of evidence, 3.

Participants: All patients being treated surgically for an OCD of the capitellum between 2006 and 2016 at one institution were reviewed for preoperative imaging. A total of 28 patients met the inclusion criteria.

Methods: Corresponding MRI and CT scans were compared retrospectively. Multiple parameters were recorded, with special emphasis on OCD lesion size, fragmentation, and tilt as well as joint surface integrity, loose bodies, and osteophytes.

Main Results: The OCD lesions were best seen on CT scans, whereas MRI T1-weighted images overestimated and T2-weighted images underestimated the size of defects. A subchondral fracture nonunion was found on CT scans in 18 patients, whereas this was seen on MRI T1-weighted images in only 2 patients (P < .001) and MRI T2-weighted images in 4 patients (P < .001). Fragmentation of the OCD fragment was found on CT scans in 17 patients but on MRI scans in only 9 patients (P = .05). Osteophytes as a sign of secondary degenerative changes were seen on CT scans in 24 patients and were seen on MRI scans in 15 patients (P = .02). Altogether, only 51 of 89 secondary changes including loose bodies, effects on the radial head and ulnohumeral joint, and osteophytes that were seen on CT scans were also seen on MRI scans (P = .002).

Conclusion: OCD fragmentation and secondary changes were more often diagnosed on CT. These factors indicate OCD instability or advanced OCD stages, which are indications for surgery. In an adolescent who is considered at risk for OCD (baseball, gymnastics, weightlifting, tennis) and who has lateral elbow joint pain with axial or valgus load bearing, CT is our imaging modality of choice for diagnosing and staging OCD of the capitellum.

Teaching point: CT is better than MRI for diagnosing and staging OCD of capitellum in adolescents.


Image quality improvement and motion degradation reduction in shoulder MR imaging: comparison of BLADE and rectilinear techniques at 3-Tesla scanning

Ajay Kohli, David T. Pilkinton, Yin Xi, Gina Cho, Daniel Moore, Daniel Mohammadi &  Avneesh Chhabra

Skeletal radiology


Background:  MR imaging of joints, particularly shoulder, requires a high degree of spatial resolution to ascertain anatomy and pathology. Unfortunately, motion artifacts can reduce the clinical quality of the examinations. BLADE sequence reduces motion degradation improving overall diagnostic imaging quality.

Question: Are BLADE sequences superior to the standard rectilinear k-space coverage turbo spin echo (TSE) sequences for shoulder imaging?

Design: Prospective study

Participants:  Over a 4-month period, fifty-seven consecutive patients (22 males, 35 females; mean age: 48.5 years, range: 23–64 years) were scanned using traditional intermediate-weighted spin echo and BLADE sequences.

Methods: Qualitative evaluation was performed by three musculoskeletal fellowship trained radiologists, each with more than 5 years of experience. Image sequences were evaluated using a Likert scale for each of the following five categories: motion degradation, ghosting/phase misregistration artifacts, star/radial encoding artifacts, fat suppression quality, and overall diagnostic quality. Additionally, image sequences were evaluated for signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) using manually drawn regions of interest (ROI) analysis.

Main Results: Ghosting and phase artifacts were lower within BLADE sequence while streak artifacts were higher (p < 0.001). Image fat suppression, tendon and labral appearances, and the overall SNR and CNR were comparable on both sequences (p > 0.05).

Conclusion: Addition of BLADE reduces motion degradation and improves overall diagnostic imaging quality. Application of BLADE in patient scans suspected of motion artifacts can reduce the frequency of repeat imaging in patients with claustrophobia or those where motion is a concern. By reducing overall imaging time and call backs, it could reduce the cost burden to patients and healthcare system.

Teaching point: MRI techniques like BLADE and PROPELLER can be utilized in patients with motion to improve quality of the otherwise suboptimal quality scans.


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