Magnetic Resonance Imaging of Accelerated Bone Remodeling.

A regional acceleration of bone remodeling may possibly follow biomechanical insults to the bone. This review assesses the literature and clinical arguments supporting the hypothetical association between accelerated bone remodeling and bone marrow edema (BME)-like signal intensity on magnetic resonance imaging. BME-like signal is defined as a confluent ill-delimited area of bone marrow with a moderate decrease in signal intensity on fat-sensitive sequences and a high signal intensity on fat-suppressed fluid-sensitive sequences. In addition to this confluent pattern, a linear subcortical pattern and a patchy disseminated pattern have also been recognized on fat-suppressed fluid-sensitive sequences. These particular BME-like patterns may remain occult on T1-weighted spin-echo images. We hypothesize that these BME-like patterns, with particular characteristics in terms of distribution and signal, are associated with accelerated bone remodeling. Limitations in recognizing these BME-like patterns are also discussed.

Imaging of treatment response and minimal residual disease in multiple myeloma: state of the art WB-MRI and PET/CT.

Bone imaging has been intimately associated with the diagnosis and staging of multiple myeloma (MM) for more than 5 decades, as the presence of bone lesions indicates advanced disease and dictates treatment initiation. The methods used have been evolving, and the historical radiographic skeletal survey has been replaced by whole body CT, whole body MRI (WB-MRI) and [18F]FDG-PET/CT for the detection of bone marrow lesions and less frequent extramedullary plasmacytomas.Beyond diagnosis, imaging methods are expected to provide the clinician with evaluation of the response to treatment. Imaging techniques are consistently challenged as treatments become more and more efficient, inducing profound response, with more subtle residual disease. WB-MRI and FDG-PET/CT are the methods of choice to address these challenges, being able to assess disease progression or response and to detect "minimal" residual disease, providing key prognostic information and guiding necessary change of treatment.This paper provides an up-to-date overview of the WB-MRI and PET/CT techniques, their observations in responsive and progressive disease and their role and limitations in capturing minimal residual disease. It reviews trials assessing these techniques for response evaluation, points out the limited comparisons between both methods and highlights their complementarity with most recent molecular methods (next-generation flow cytometry, next-generation sequencing) to detect minimal residual disease. It underlines the important role of PET/MRI technology as a research tool to compare the effectiveness and complementarity of both methods to address the key clinical questions.

Soft tissue recurrence of an osteoid osteoma: an exceptional observation.

We report the observation of the soft tissue recurrence of an osteoid osteoma (OO) in a 26-year-old man initially complaining of post-traumatic pain and swelling of the right ankle. A first arthroscopic resection was performed after the misdiagnosis of "bone irregularities" observed on computed tomography (CT) and magnetic resonance imaging (MRI). The diagnosis of OO was made by histological analysis of the resection material. The patient became asymptomatic for 5 years until the symptoms progressively recurred. Follow-up MRI and CT studies demonstrated a nodular bony focus within the periarticular soft tissues of the ankle. The lesion was removed, and histological analysis confirmed the diagnosis of a whole viable OO. This observation likely resulted from the displacement of the initial lesion during the initial arthroscopic procedure. This case report highlights the possibility of recurrence of OO in the soft tissues.

Value of CT to detect radiographically occult injuries of the proximal femur in elderly patients after low-energy trauma: determination of non-inferiority margins of CT in comparison with MRI.

PURPOSE: To determine the margins of non-inferiority of the sensitivity of CT and the sample size needed to test the non-inferiority of CT in comparison with MRI. MATERIALS AND METHODS: During a 2-year period, elderly patients with suspected radiographically occult post-traumatic bone injuries were investigated by CT and MRI in two institutions. Four radiologists analyzed separately the CT and MRI examinations to detect post-traumatic femoral injuries. Their sensitivities at CT (SeCT) and MRI (SeMRI) were calculated with the reference being a best valuable comparator (consensus reading of the MRI and clinical follow-up). ROC analysis followed by an exact test (Newcombe's approach) was performed to assess the 95% confidence interval (CI) for the difference SeCT-SeMRI for each reader. A sample size calculation was performed based on our observed results by using a one-sided McNemar's test. RESULTS: Twenty-nine out of 102 study participants had a post-traumatic femoral injury. SeCT ranged between 83 and 93% and SeMRI ranged between 97 and 100%. The 95% CIs for (SeCT-SeMRI) were [- 5.3%, + 0.8%], (pR1 = 0.1250), [- 4.5%; + 1.2%] (pR2 = 0.2188), [- 3.4%; + 1.1%] (pR3 = 0.2500) to [- 3.8%; + 1.6%] (pR4 = 0.3750) according to readers, with a lowest limit for 95% CIs superior to a non-inferiority margin of (- 6%) for all readers. A population of 440 patients should be analyzed to test the non-inferiority of CT in comparison with MRI. CONCLUSION: CT and MRI are sensitive for the detection of radiographically occult femoral fractures in elderly patients after low-energy trauma. The choice between both these modalities is a compromise between the most available and the most sensitive technique. KEY POINTS: • The sensitivity of four separate readers to detect radiographically occult post-traumatic femoral injuries in elderly patients after low-energy trauma ranged between 83 and 93% at CT and between 97 and 100% at MRI according to a best valuable comparator including MRI and clinical follow-up. • CT is a valuable alternative method to MRI for the detection of post-traumatic femoral injuries in elderlies after low-energy trauma if a 6% loss in sensitivity can be accepted in comparison with MRI. • The choice between CT and MRI is a compromise between the most available and the most sensitive technique.

Osteoid osteoma of the hip: imaging features.

Osteoid osteoma (OO), a small bone tumor relatively common in young subjects, frequently involves the hip. In addition to typical findings, we emphasize unsuspected clinical and imaging features including painless OO causing limping gait, non-visibility of totally mineralized nidus, absence of hyperostosis or adjacent edema, and recurrence at distance from the initial location. We also discuss the option of medical treatment for some cases of deep hip locations.

Primary infectious costochondritis due to Prevotella nigrescens in an immunocompetent patient: clinical and imaging findings.

Infection of costal cartilage is a rare observation. We report the case of a 43-year-old male patient without relevant history who presented with a progressive painful swelling of the left chest wall since 4 months. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated an abscess within the left ninth costal cartilage with surrounding reactive changes. A CT-guided biopsy was performed and the culture of the sample revealed the presence of Prevotella nigrescens. Musculoskeletal infections by Prevotella are rarely described in the literature, Prevotella oralis and Prevotella bivia being the most frequently observed pathogens. These infections usually originate from a hematogenous spread after thoracic surgery or dental procedure. In our patient, conservative treatment was chosen. A clinical improvement was noted after 1-month antibiotherapy, confirmed by short-term and 6-month imaging follow-up showing the complete disappearance of all previously observed abnormalities.

Whole body MRI in spondyloarthritis (SpA): Preliminary results suggest that DWI outperforms STIR for lesion detection.

PURPOSE: To compare the diagnostic accuracy of DWI and STIR sequences in Whole body (WB) MRI of SpA patients. MATERIALS AND METHODS: Twenty consecutive patients with confirmed active SpA and 20 controls were investigated with identical WB MRI protocols, including DWI and STIR images. Two observers recorded 'lesions' (high signal intensity foci on STIR and high b-value DWI) in 17 anatomical areas, making a 17-point 'area score' and a 40-point 'lesion score'. ROC performance, inter-observer agreement, correlation with clinical parameters and spine and sacro-iliac joints (SIJ) MRI scores were assessed. RESULTS: SpA patients had significantly higher lesion scores on DWI than on STIR (p<0.025). The lesion score area under the curve was significantly higher with DWI (99.9) than with STIR (95.8, p=0.02). DWI lesion score ≥5 had both sensitivity and specificity ≥85 %. With STIR the best threshold ≥3 yielded sensitivity ≥85 % and specificity ≥60 %. DWI area score ≥3 yielded sensitivity ≥85 % and specificity ≥80 %. With STIR the best threshold ≥4 yielded sensitivity ≥70 % and specificity ≥80 %. Inter-observer agreement was strong for both sequences. In patients, the lesion score was positively correlated with ASDAS-CRP, log(CRP), and local MRI scores. CONCLUSIONS: DWI is a promising alternative to STIR in WB MRI to detect active SpA lesions. KEY POINTS: • DWI is a robust alternative to STIR in WBMRI in SpA. • DWI might be superior in discriminating relevant inflammatory and degenerative changes. • Positive correlations exist between WB MRI, clinical, biological, local MRI data. • Distribution and frequency of abnormal MRI findings in SpA are highlighted.

Pseudoaneurysms after Ankle Sprain: Report of Three Cases Successfully Cured by Nonsurgical Treatment.

Pseudoaneurysm is a rare complication of ankle sprain, with 18 case reports published in the current literature. In the vast majority of the cases, they were treated surgically. We present 3 cases of pseudoaneurysm following ankle sprain, treated by nonsurgical methods in 2 cases, and spontaneously healed in another. The diagnosis was made between 2 and 4 weeks after traumatism, by ultrasonography and arteriography in 2 cases, and only by ultrasonography in a third case. The pseudoaneurysms originated respectively from the perforating fibular artery, the dorsal pedis artery, and a lateral malleolar artery. Largest diameters of the pseudoaneurysms ranged from 2.4 to 6 cm. Patients were successfully treated by thrombin injection in a case and by coil embolization in another. Spontaneous thrombosis was demonstrated at follow-up in the third case. These cases suggest that a nonsurgical treatment can be considered for pseudoaneurysms complicating ankle sprains.

Calcaneal cysts and lipomas: a common pathogenesis?

Calcaneal cysts and lipomas are relatively rare, benign bone lesions. They are similar in many ways, including in their location and radiological appearance, but their content differs. Cysts contain fluid whereas lipomas contain fat, although some lesions may exhibit a mixed content. The pathogenesis of the two entities is the subject of controversy. The theory that calcaneal cysts may result from lipomatous necrosis has been widely suggested in the literature, but no such progression has ever been shown. The contrary hypothesis has also been considered, i.e., that the content of regressing cysts may be replaced by fatty marrow, leading to a lipoma-like appearance. This second theory is based on indirect arguments, notably that lipomas have a similar location to intraosseous calcaneal ganglion cysts that arise from the subtalar joint and that patients are older in cases of calcaneus lipomas than in cases of calcaneus cysts. We offer an additional argument in favor of this hypothesis. We present an original observation of a calcaneal cyst incidentally discovered in a 15-year-old male whose spontaneous evolution 3 and 7 years later revealed progressive replacement of its fluid content by fat.

[MRI of axial spondyloarthritis: diagnostic role and pitfalls]. / IRM dans le diagnostic des spondyloarthrites axiales: utilité et pièges diagnostiques.

MRI has become a major tool for the diagnosis of axial spondyloarthritis and provides objective signs based on which therapy can be initiated. In clinical practice, ASAS classification criteria are often applied for the diagnosis of spondyloarthritis at a pre-radiographic stage. However, MRI signs of spondyloarthritis as stated in ASAS criteria lack specificity, and can be encountered in a wide array of diagnoses, in particular degenerative and mechanical conditions. In this article, we will review the role of MRI in the diagnosis and classification of spondyloarthritis, general technical considerations, the elementary MRI signs of axial spondyloarthritis, as well as diagnostic pitfalls. We also provide a practical approach on how to avoid overdiagnosis of spondyloarthritis and to improve the diagnostic value of MRI.

The Increasing Spectrum of Indications of Whole-Body MRI Beyond Oncology: Imaging Answers to Clinical Needs.

Whole-body coverage using MRI was developed almost 2 decades ago. The first applications focused on the investigation of the skeleton to detect neoplastic disease, mainly metastases from solid cancers, and involvement by multiple myeloma and lymphoma. But the extensive coverage of the whole musculoskeletal system, combined with the exquisite sensitivity of MRI to tissue alteration in relation to different pathologic conditions, mainly inflammation, has led to the identification of a growing number of indications outside oncology. Seronegative rheumatisms, systemic sclerosis, inflammatory diseases involving muscles or fascias, and multifocal osseous, vascular, or neurologic diseases represent currently validated or emerging indications of whole-body MRI (WB-MRI). We first illustrate the most valuable indications of WB-MRI in seronegative rheumatisms that include providing significant diagnostic information in patients with negative or ambiguous MRI of the sacroiliac joints and the lumbar spine, assessing disease activity in advanced (ankylosed) central disease, and evaluating the peripherally dominant forms of spondyloarthropathy. Then we review the increasing indications of WB-MRI in other rheumatologic and nonneoplastic disorders, underline the clinical needs, and illustrate the role of WB-MRI in the positive diagnosis and evaluation of disease burden, therapeutic decisions, and treatment monitoring.

Intraosseous migration of tendinous calcifications: cortical erosions, subcortical migration and extensive intramedullary diffusion, a SIMS series.

Calcium hydroxyapatite crystal deposition is a common disorder, which sometimes causes acute pain as calcifications dissolve and migrate into adjacent soft tissue. Intraosseous calcium penetration has also been described. We illustrate the appearance of these lesions using a series of 35 cases compiled by members of the French Society of Musculoskeletal Imaging (Société d'Imagerie Musculo-Squelettique, SIMS). The first group in our series (7 cases) involved calcification-related cortical erosions of the humeral and femoral diaphyses, in particular at the pectoralis major and gluteus maximus insertions. A second group (28 cases) involved the presence of calcium material in subcortical areas. The most common site was the greater tubercle of the humerus, accompanying a calcifying tendinopathy of the supraspinatus. In addition, an extensive intramedullary diffusion of calcium deposits was observed in four of these cases, associated with cortical erosion in one case and subcortical lesions in three cases. Cortical erosions and intraosseous migration of calcifications associated with calcific tendinitis may be confused with neoplasm or infection. It is important to recognize atypical presentations of hydroxyapatite deposition to avoid unnecessary investigation or surgery.

Anatomic features associated with femoroacetabular impingement are equally common in hips of old and young asymptomatic individuals without CT signs of osteoarthritis.

OBJECTIVE: The purpose of this article is to evaluate and compare the prevalence and measurement values of CT signs of femoroacetabular impingement (FAI) in asymptomatic hips without CT signs of osteoarthritis between two age groups: younger than 40 years and older than 60 years. SUBJECTS AND METHODS: We prospectively included patients undergoing thoracoabdominopelvic MDCT for nonorthopedic indications with asymptomatic hips and excluded hips with signs of osteoarthritis seen on CT. Two age groups including 75 hips each were enrolled (< 40 years old: mean age, 31 years; 15 women; > 60 years old: mean age, 66 years; 21 women). Two observers independently performed the image analysis. Prevalences and quantitative values of the cam (alpha angle and femoral head-neck offset) and pincer (acetabular version angle, acetabular index, lateral center-edge angle, crossover sign, and posterior wall sign) FAI morphotypes were compared using both difference and equivalence tests. Intraobserver agreement was assessed. RESULTS: The prevalence of CT signs of FAI were high and showed great variation depending on the signs and cutoff values, in both groups (9-63% for cam; 3-50% for pincer). The prevalence and measurement values of CT signs of the cam morphotype were equivalent between the two age groups. The prevalence and measurement values of CT signs of the pincer morphotype were statistically equivalent between the age groups except for the acetabular version angle, lateral center-edge angle, and crossover sign for which no statistical difference was found, but statistical equivalence was not reached. Interobserver and intraobserver agreement were moderate to almost perfect (κ = 0.72-0.89; intraclass correlation coefficient, 0.42-0.94). CONCLUSION: The prevalence and measurement values of most CT signs of FAI morphotypes were high and equivalent between the two age groups of patients with asymptomatic nonosteoarthritic hips.

Low-dose multidetector computed tomography of the cervical spine: optimization of iterative reconstruction strength levels.

BACKGROUND: Iterative reconstruction (IR) techniques reduce image noise in multidetector computed tomography (MDCT) imaging. They can therefore be used to reduce radiation dose while maintaining diagnostic image quality nearly constant. However, CT manufacturers offer several strength levels of IR to choose from. PURPOSE: To determine the optimal strength level of IR in low-dose MDCT of the cervical spine. MATERIAL AND METHODS: Thirty consecutive patients investigated by low-dose cervical spine MDCT were prospectively studied. Raw data were reconstructed using filtered back-projection and sinogram-affirmed IR (SAFIRE, strength levels 1 to 5) techniques. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured at C3-C4 and C6-C7 levels. Two radiologists independently and blindly evaluated various anatomical structures (both dense and soft tissues) using a 4-point scale. They also rated the overall diagnostic image quality using a 10-point scale. RESULTS: As IR strength levels increased, image noise decreased linearly, while SNR and CNR both increased linearly at C3-C4 and C6-C7 levels (P < 0.001). For the intervertebral discs, the content of neural foramina and dural sac, and for the ligaments, subjective image quality scores increased linearly with increasing IR strength level (P ≤ 0.03). Conversely, for the soft tissues and trabecular bone, the scores decreased linearly with increasing IR strength level (P < 0.001). Finally, the overall diagnostic image quality scores increased linearly with increasing IR strength level (P < 0.001). CONCLUSION: The optimal strength level of IR in low-dose cervical spine MDCT depends on the anatomical structure to be analyzed. For the intervertebral discs and the content of neural foramina, high strength levels of IR are recommended.

Diagnosis failure led to the recurrence of an intra-articular osteoid osteoma at the talus neck after arthroscopic excision.

Juxta-articular localization is not exceptional for an osteoid osteoma of the ankle. Arthroscopic treatment has been recently proposed. A case of recurrence of an osteoid osteoma at the talar neck is reported after arthroscopic resection performed following a diagnosis failure. The need for accurate imaging technique to precisely define and localize the nidus and the requirement to include osteoid osteoma in the differential diagnosis of monoarticular pain are discussed.

Subchondral insufficiency fractures, subchondral insufficiency fractures with osteonecrosis, and other apparently spontaneous subchondral bone lesions of the knee-pathogenesis and diagnosis at imaging.

Subchondral insufficiency fractures (SIFs) and SIFs with osteonecrosis (SIF-ONs) of the knee (previously misnamed spontaneous osteonecrosis of the knee (SONK)) are bone lesions that appear without prior traumatic, tumoral, or inflammatory event.Both conditions are characterized in the early stages by epiphyseal bone marrow edema (BME)-like signal at MRI. However, while SIFs usually heal spontaneously, they can also evolve to osteonecrosis (i.e., SIF-ON), which may progress to an irreversible collapse of the articular surface. Careful analysis of other MRI signs may help differentiate the two conditions in the early phase. In SIFs, the BME edema-like signal extends to the area immediately adjacent to the subchondral plate, while in SIF-ONs, this subchondral area shows low signal intensity on fluid-sensitive MR images due to altered bone marrow. The thickness and length of subchondral areas with low fluid-sensitive signal intensity are important factors that determine the prognosis of SIF-ONs. If they are thicker than 4 mm or longer than 14 mm, the prognosis is poor. The differential diagnosis of SIFs and SIF-ONs include bone lesions associated with the "complex regional pain syndrome" (CRPS), epiphyseal osteonecrosis of systemic origin, and those related to cartilage pathology.Clinical relevance statement Imaging plays an essential role in diagnosing subchondral insufficiency fractures (SIFs) from subchondral insufficiency fractures with osteonecrosis (SIF-ONs) and collapse, as well as in distinguishing them from other spontaneous knee subchondral bone lesions presenting with bone marrow edema-like signal.Key points• Subchondral insufficiency fractures may affect the knee, especially in older adults.• Subchondral insufficiency fractures usually heal spontaneously.• Sometimes, subchondral osteonecrosis and collapse may complicate subchondral insufficiency fractures.• Bone marrow-like edema is an aspecific sign seen in all these lesions.• Degraded marrow in osteonecrosis complicating fractures is hypointense on fluid-sensitive sequences.

Evaluation of rotator cuff tendon tears: comparison of multidetector CT arthrography and 1.5-T MR arthrography.

PURPOSE: To compare the diagnostic performance of multidetector computed tomographic (CT) arthrography and 1.5-T magnetic resonance (MR) arthrography in the evaluation of rotator cuff lesions, with arthroscopic correlation. MATERIALS AND METHODS: This study was approved by the institutional ethical committee, and informed consent was obtained from all patients. CT and MR arthrographic images prospectively obtained in 56 consecutive patients, following the same arthrographic procedure, were independently evaluated by two radiologists. Arthroscopy, performed within 1 month of the imaging, was used as the reference standard. Sensitivity and specificity of CT and MR arthrography were compared by using the McNemar test. Interobserver and intertechnique agreement for detecting rotator cuff lesions were measured and compared with κ and Z statistics. The Bland-Altman method was used to determine interobserver and intertechnique agreement for measuring tendon tears. For grading fatty infiltration of rotator cuff muscles, κ and Z statistics were used. RESULTS: There was no statistically significant difference in sensitivity and specificity between CT arthrography and MR arthrography in depiction of rotator cuff lesions. The respective sensitivity and specificity of CT arthrography were 92% and 93%-97% for the supraspinatus, 100% and 77%-79% for the infraspinatus, 75%-88% and 85%-90% for the subscapularis, and 55%-65% and 100% for the biceps tendon. The respective sensitivity and specificity of MR arthrography were 96% and 83%-93% for the supraspinatus, 88%-100% and 81%-83% for the infraspinatus, 75%-88% and 90%-100% for the subscapularis, and 65%-85% and 100% for the biceps tendon. Interobserver agreement was substantial to almost perfect (κ = 0.744-0.964 for CT arthrography; κ = 0.641-0.893 for MR arthrography), and intertechnique agreement was almost perfect (κ > 0.819). CT and MR arthrography both yielded moderate interobserver and intertechnique agreement for measuring rotator cuff tears and grading muscle fatty infiltration. CONCLUSION: Data suggest that CT and MR arthrography have similar diagnostic performance for the evaluation of rotator cuff tendon tears.

Glomus tumour eroding the medial facet of the patella: a case report.

Glomus tumours are benign lesions occurring essentially in the hand, with a predilection for the subungueal area. Even though they have been reported in literature, extradigital localisations of glomus tumours are frequently misdiagnosed; they never lead to bone osteolysis. We report the case of a patient who presented with a typical patellofemoral syndrome due to a glomus tumour that eroded the medial facet of the patella. MRI, which is the gold standard for the diagnosis, showed a well-delineated spherical tumour with enhancement after Gadolinium injection. CT Scan excluded an osteoid osteoma and showed the erosion of the patella. The lesion was surgically resected and the histological examination established the definitive diagnosis.

Presumed intraarticular gas microbubbles resulting from a vacuum phenomenon: visualization with ultrasonography as hyperechoic microfoci.

OBJECTIVE: Hyperechoic microfoci are sometimes visualized in normal joints. We hypothesized that these microfoci may correspond to gas microbubbles produced by a vacuum phenomenon. The purpose of our study was to demonstrate the possibility of generating intraarticular hyperechoic microbubbles by creating a vacuum phenomenon through traction on a metacarpophalangeal joint. MATERIALS AND METHODS: We applied manual traction to the second metacarpophalangeal (MCP) joint of 22 volunteer subjects to separate articular surfaces with the aim of producing a vacuum. For one subject, the production of a vacuum was verified on a radiograph performed during the traction maneuver. For all subjects, ultrasonographic examination of the MCP joints was performed before, during, and after traction maneuvers. Two radiologists evaluated the presence of intraarticular hyperechoic microfoci and measured the widening of the joint space during traction. RESULTS: In the first subject, the widening of the joint space and the production of an intraarticular gas-like cavity by traction was confirmed on the radiograph. In 10 out of the 22 volunteers, the widening of the joint space was immediately followed by the appearance of a large intraarticular hyperechoic band, which disappeared when the traction was stopped, followed by the appearance of hyperechoic microfoci that persisted several minutes. The widening of the joint during the traction maneuver was greater in the group where hyperechoic foci were produced than in the group with no hyperechoic foci (mean 2.5 vs. 1.2 mm and 2.2 vs. 0.8 mm, respectively, for observers 1 and 2; P < 0.05, Mann-Whitney U test). CONCLUSION: Intraarticular hyperechoic microfoci may be produced and persist in normal joints after a traction maneuver. They are presumed to correspond to microbubbles created by a transient vacuum phenomenon.