Smartphone application with 3D-printed needle guide for faster and more accurate CT-guided interventions in a phantom.

OBJECTIVE: This study is to determine whether a needle guidance device combining a 3D-printed component with a smartphone would decrease the number of passes and time required to perform a standard CT-guided needle procedure in a phantom study. MATERIALS AND METHODS: A 3D-printed mechanical guide with built-in apertures for various needle sizes was designed and printed. It was mounted on a smartphone and used to direct commercially available spring-loaded biopsy devices. A smartphone software application was developed to use the phone's sensors to provide the real-time location of a lesion in space, based on parameters derived from preprocedural CT images. The physical linkage of the guide, smartphone, and needle allowed the operator to manipulate the assembly as a single unit, with real-time graphical representation of the lesion shown on the smartphone display. Two radiology trainees and 3 staff radiologists targeted 5 lesions with and without the device (50 total procedures). The number of passes and time taken to reach each lesion were determined. RESULTS: Use of the smartphone needle guide decreased the mean number of passes (with guide, 1.8; without guide, 3.4; P < 0.001) and mean time taken (with guide, 1.6 min; without guide, 2.7 min; P = 0.005) to perform a standard CT-guided procedure. On average, the decreases in number of passes and procedure time were more pronounced among trainees (P < 0.001). CONCLUSION: The combination of a mechanical guide and smartphone can reduce the number of needle passes and the amount of time needed to reach a lesion in a phantom for both trainees and experienced radiologists.

Updates and Ongoing Challenges in Imaging of Multiple Myeloma: AJR Expert Panel Narrative Review.

Advances in the understanding and treatment of multiple myeloma have led to the need for more sensitive and accurate imaging of intramedullary and extramedullary disease. This role of imaging is underscored by recently revised imaging recommendations of the International Myeloma Working Group (IMWG). This narrative review discusses these recommendations from the IMWG for different disease stages, focusing on advanced whole-body modalities, and addresses related challenges and controversies. In the recommendations, whole-body low-dose CT is central in initial patient assessment, replacing the conventional skeletal survey. Although the recommendations favor MRI for diagnosis because of its superior sensitivity and utility in identifying myeloma-defining events, FDG PET/CT is recommended as the modality of choice for assessing treatment response. Consensus opinions are offered regarding the role of imaging in multiple myeloma for characterization of disease distribution, determination of prognosis, and response evaluation.

Magnetic resonance imaging of deltoid muscle/tendon tears: a descriptive study.

OBJECTIVE: To describe the MRI features of deltoid tears and to evaluate tear characteristics in patient groups based on history of trauma and rotator cuff tear (RCT). MATERIALS AND METHODS: The records of patients who underwent shoulder MRI at our institution between July 2007 and June 2018 were retrospectively reviewed to identify deltoid tears, and patients were divided into groups based on history of recent trauma and presence of RCT. Images were reviewed to identify the location and size of the deltoid tear; the presence or absence of RCT, muscle atrophy, tendon retraction, humeral head subluxation, soft tissue edema, and additional pathologies were also noted. Medical records were reviewed for information about history of steroid injection, previous rotator cuff surgery, and treatments used. RESULTS: Among 69 patients with deltoid tears (45 men; mean age, 65.2 years; range, 19-89 years), patients with RCTs and no trauma had the highest frequency of deltoid tears in the middle portion (p = 0.005). Only patients with RCTs had undergone steroid injection or rotator cuff surgery. Two patients had deltoid tear without RCT and without recent trauma; these patients demonstrated evidence of calcific tendinopathy and chronic subacromial-subdeltoid bursitis. CONCLUSION: The middle (acromial) portion of the deltoid is more frequently affected in patients with RCTs than in those with trauma. Although deltoid tears are commonly associated with RCT, calcific tendinopathy and chronic bursitis may also be seen in patients with deltoid tears.

Does PET/CT Aid in Detecting Primary Carcinoma in Patients with Skeletal Metastases of Unknown Primary?

BACKGROUND: Patients older than 40 years presenting with osteolytic bone lesions are likely to have a diagnosis of carcinoma, even if they had no prior cancer diagnosis. For patients with no prior cancer diagnosis, there is a well-accepted algorithm to determine a potential primary site. That algorithm, however, leaves approximately 15% of people without a detectable primary tumor site, making treatment decisions extremely difficult. Positron emission tomography (PET) fused with CT, more commonly known as PET/CT, has emerged as an important staging modality for many other malignancies but has been used in a very limited fashion in musculoskeletal oncology. QUESTIONS/PURPOSES: We asked (1) What is the ability of PET/CT to detect the source of the primary tumor in patients with a skeletal metastasis of unknown primary? (2) How does PET/CT perform in detecting metastases in other sites in patients with a skeletal metastasis of unknown primary? METHODS: A retrospective analysis between 2006 and 2016 of the pathology database of a single tertiary center identified 35 patients with a biopsy-proven skeletal metastasis (histologically confirmed carcinoma or adenocarcinoma) and a PET/CT scan that was performed after the standard diagnostic evaluation of the primary cancer site. Patients were identified through use of our pathology database to identify all biopsy-proven bone carcinomas. This was then cross referenced with our imaging database to identify all patients who were at any time evaluated with PET/CT. During this time, we identified 1075 patients with biopsy-proven metastatic bone disease through our pathology database. Any indication for a PET/CT was included, and was most often done for staging of the identified malignancy or evaluation for the unknown source. Data regarding the ability of PET/CT to find or confirm the primary cancer and all metastatic sites were evaluated. The standard diagnostic evaluation (history and physical, laboratory evaluation, CT of the chest/abdomen/pelvis and whole body bone scan) identified the primary cancer in 22 of the 35 patients. Among the 35 patients, there were a total of 176 metastatic sites of disease identified, with 115 identified with the standard diagnostic evaluation (before PET/CT). RESULTS: Among patients with a skeletal metastasis of unknown primary, PET/CT was unable to identify the primary cancer in 12 of 13 patients. PET/CT confirmed the site of the known primary cancer in all 22 patients. There were 176 total metastatic sites. Of the 115 metastases known before PET/CT, PET/CT failed to identify three of 115 (3% false-negative rate). CONCLUSIONS: PET/CT may not provide any additional benefit over the standard evaluation for identification of the primary cancer in patients with a skeletal metastasis of unknown primary, although it may have efficacy as a screening tool equivalent or superior to the standard diagnostic algorithm for evaluation of the overall metastatic burden in these patients. LEVEL OF EVIDENCE: Level III, diagnostic study.

Isolated septic facet joints: an underdiagnosed distinct clinical entity.

OBJECTIVES: We review a series of isolated septic facet joints (ISFJ) that present as a distinct clinical entity compared with spondylodiscitis. We aim to raise awareness that septic facet joints are not a rare entity in the era of modern imaging. METHODS: We reviewed 353 patients with confirmed spine infections from 2008 to 2017. Of the 353 cases, there were 152 septic facet joints based on MR imaging. Sixty-two presented as ISFJ without evidence of spondylodiscitis and were reviewed. RESULTS: Patients were predominantly male 38/62 (61%). The mean age was 56.7 years. Onset of back pain was more acute compared with spondylodiscitis and usually unilateral. The distribution was as follows: 6 cervical, 12 thoracic, and 44 lumbar facets. The majority of ISFJ, 53/62 (85%), were associated with an epidural abscess (EDA) 53/62. The cervical and thoracic EDA required surgical decompression more frequently than lumbar; 100%, 75%, and 53% respectively. Pathogen was identified in 59/62 (95%) cases. Most cases were associated with bacteremia 50/62 (81%). Seven ISFJ were introduced iatrogenically. All iatrogenic ISFJ required surgical decompression. CONCLUSION: Septic facet joints are not rare, but frequently overlooked as the origin of an epidural abscess. The majority of cases are hematogenously seeded and associated with bacteremia. Surgical decompression is frequently required secondary to the high incidence of associated epidural abscess. Iatrogenic septic facet joints are rare but associated with significant morbidity. From a clinical standpoint, it is helpful to delineate the origin of EDA as either secondary to spondylodiscitis or SFJ.

Case 272: Decubital Ischemic Fasciitis.

HistoryA 92-year-old bedridden woman presented to the emergency department from an assisted living facility with fever, cough, and swelling over the right lateral hip. She had baseline dementia and frailty and had been bedridden for 4 years. She did not have any recent falls or history of trauma at the site of swelling. She had a history of diffuse large B-cell lymphoma that had been diagnosed and treated 7 years ago, and thoracoabdominal CT at last follow-up 3 years ago did not show any recurrence. Physical examination findings were unremarkable except for a painful hard and fixed mass measuring approximately 5 × 5 × 10 cm (in the transverse, anteroposterior, and craniocaudal directions, respectively) located at the right lateral superior thigh. The overlying skin was intact, without any color changes. Pertinent blood test results showed an increased white blood cell count of 13,000/µL (13 × 109/L) (normal range, 3700-11,000/µL [3.7-11 × 109/L]). The remaining hematologic and biochemical test results were normal. Abdominal and pelvic CT performed at presentation did not show any abnormal lymph nodes. Because chest radiography showed consolidation in addition to typical clinical picture, the patient was diagnosed with pneumonia and underwent antibiotic treatment for 3 weeks. US and Doppler US of the mass were performed. MRI was not performed because the patient had a pacemaker; instead, CT of the lower extremity was performed.

Case 272.

History A 92-year-old bedridden woman presented to the emergency department from an assisted living facility with fever, cough, and swelling over the right lateral hip. She had baseline dementia and frailty and had been bedridden for 4 years. She did not have any recent falls or history of trauma at the site of swelling. She had a history of diffuse large B-cell lymphoma that had been diagnosed and treated 7 years ago, and thoracoabdominal CT at last follow-up 3 years ago did not show any recurrence. Physical examination findings were unremarkable except for a painful hard and fixed mass measuring approximately 5 × 5 × 10 cm (in the transverse, anteroposterior, and craniocaudal directions, respectively) located at the right lateral superior thigh. The overlying skin was intact, without any color changes. Pertinent blood test results showed an increased white blood cell count of 13 000/µL (13 ×109/L) (normal range, 3700-11 000/µL [3.7-11 ×109/L]). The remaining hematologic and biochemical test results were normal. Abdominal and pelvic CT performed at presentation did not show any abnormal lymph nodes. Because chest radiography showed consolidation in addition to typical clinical picture, the patient was diagnosed with pneumonia and underwent antibiotic treatment for 3 weeks. US ( Fig 1 ) and Doppler US ( Fig 2 ) of the mass were performed. MRI was not performed because the patient had a pacemaker; instead, CT of the lower extremity was performed ( Fig 3a , 3b ). Figure 1: US image of the mass at the level of the greater trochanter. Figure 2: Doppler US image of the caudal portion of the mass. Figure 3a: (a) Axial unenhanced CT image of the lesion at the level of the greater trochanter. (b) Coronal unenhanced CT image of the mass at the level of the greater trochanter. Figure 3b: (a) Axial unenhanced CT image of the lesion at the level of the greater trochanter. (b) Coronal unenhanced CT image of the mass at the level of the greater trochanter.

Bony changes of the tibia secondary to pes anserine bursitis mimicking neoplasm.

OBJECTIVE: To describe the radiological features of pes anserine bursitis with intramedullary extension and cortical scalloping and to determine the prevalence of these bony changes among patients with pes anserine bursitis. MATERIALS AND METHODS: Reports of knee magnetic resonance imaging (MRI) examinations performed at our institution between July 2007 and June 2017 in patients with pes anserine bursitis were retrospectively reviewed, and a total of 542 cases showing MR evidence of pes anserine bursitis were identified. From these, cases of pes anserine bursitis with intramedullary extension and cortical scalloping were identified. Two experienced musculoskeletal radiologists evaluated the MRI by consensus. The medical records of these patients were also reviewed. RESULTS: Eight patients were diagnosed with pes anserine bursitis with bony changes (prevalence, 1.47% [8 out of 542]), over the study period. All of these patients had a history of chronic knee pain. Seven patients also underwent radiography at the time of diagnosis; these images demonstrated variable appearances depending on the depth of the cortical scalloping and intramedullary extension. On MRI, all patients demonstrated a mass-like fluid extension around the pes anserine bursa and into the bone. None of the patients underwent biopsy; diagnosis was based on MRI features alone. CONCLUSION: Pes anserine bursitis with intramedullary extension is an unusual presentation of bursitis that may simulate a neoplasm clinically and radiologically. To avoid misdiagnosis, radiologists should be aware of the occurrence of osseous changes in the tibia confluent with pes anserine bursitis.

Quantification of fat content in lipid-rich myxoid liposarcomas with MRI: a single-center experience with survival analysis.

OBJECTIVE: To determine the fat content of myxoid liposarcomas (MLS) on MRI and to identify any association between lipid content and survival. MATERIALS AND METHODS: The fat percentage of MLS diagnosed between January 2006 and December 2016 at a single institution was assessed by two radiologists on preoperative MR images. A Cox proportional hazard model was used to determine any association between tumor fat percentage and survival time. Tumor fat percentage was the single predictor in the model. A significance level of 0.05 was used. The Kaplan-Meier estimator was also used to provide a nonparametric estimate of the survivor function within the entire sample and within two patient subgroups consists of lipid-rich and lipid-poor tumors. Lipid-rich tumors were defined as any tumors showing more than 20% of fat on MRI. A 20% cutoff was determined arbitrarily. RESULTS: Of the 43 cases identified through retrospective review, 8 tumors demonstrated ≥10% fat on MRI, and 4 tumors demonstrated ≥20% fat (highest fat percentage, 38%). There was no significant survival difference between patients with high tumor fat, which was defined as ≥20% fat, compared with those with little to no tumor fat. CONCLUSION: Myxoid liposarcomas may demonstrate a higher fat content on MRI than has previously been reported in the literature. Increased tumor fat percentage in lipid-rich tumors was not found to be associated with increased risk of death. Radiologists must be aware of the existence of MLS lesions with higher fat content.

CT-guided percutaneous biopsy of sclerotic bone lesions: diagnostic outcomes.

OBJECTIVE: To determine the diagnostic yield of CT-guided percutaneous biopsy of densely sclerotic bone lesions. MATERIALS AND METHODS: We retrospectively analyzed CT-guided percutaneous bone biopsies performed at our institution from September 2008 through August 2011 (329 cases) and from September 2012 through August 2015 (324 cases) after adoption of a battery-powered drill system (OnControl). Bone lesions were included in the analysis if they were >70% sclerotic by visual inspection, had a density > 2 times that of adjacent trabecular bone, and had an attenuation of ≥250 HU. Pathological fractures, diskitis-osteomyelitis, and osteoid osteomas were excluded. Eligible cases were characterized by lesion location, maximum lesion diameter, mean density, biopsy needle type and gauge, reported complications, and histological diagnosis. Clinical and imaging follow-up was used to confirm histological diagnosis. Cases in which a benign histological diagnosis could not be confirmed by imaging over a minimum period of 1 year were excluded. RESULTS: A total of 37 biopsies of sclerotic bone lesions met the inclusion criteria, 17 of which were performed with a power drill needle and 20 of which were performed with a manually driven needle. The mean lesion density was 604.1 HU. The overall diagnostic yield was 78.4%; overall diagnostic accuracy was 94.6%, and the false-negative rate was 5.4%. Diagnostic yield and accuracy were 82.4% and 100% respectively, with a power drill and 75% and 90% respectively, with a manual device. Diagnostic yield for lesions ≥700 HU was 90% (9 out of 10). CONCLUSION: Densely sclerotic bone lesions are amenable to percutaneous needle biopsy.

Air-blocking ablation of osteoid osteoma; a technical note.

Osteoid osteoma accounts for approximately 10-12% of all benign bone tumors. Surgery was the treatment of choice for osteoid osteomas until percutaneous radiofrequency ablation (RFA) was introduced in 1992. Although RFA is generally considered curative in the treatment of osteoid osteoma, disease recurrence after ablation has been reported. We report a case in which RFA was delayed by the presence air surrounding the ablation probe. In this case, ablation could only be performed after the probe was removed and saline was injected through the introducer needle to displace the air. Air is reported to decrease radiofrequency energy transmission; a simple measure like injecting saline through an introducer could prevent such a complication. We also suggest that partial air in the ablation bed surrounding the ablation probe could decrease the energy transmission and may be one of the causes of early recurrences. Saline injection could be helpful in providing a more reliable environment for ablation.

Radiation-induced focal cortical necrosis of the femur presenting as a lytic lesion.

Management of soft tissue sarcomas is often complicated, requiring radiation before and in some cases after limb-sparing surgery. Radiation necrosis is a severe complication after radiation treatment and is typically dose related and involves medullary bone. We report on two cases of hitherto unreported focal circumscribed intra-cortical lytic lesions within the radiation portal, which appeared 19 months and 31 months, respectively, after the conclusion of radiation treatment. Both patients had a history of soft tissue sarcoma treated with radiation (66 Gy) and surgical resection. Biopsy of these lesions showed necrotic bone attributed to radiation.

Osteoid osteoma of the hand and foot in children successfully treated with radiofrequency neurotomy probes.

Osteoid osteoma is a common benign tumor that is typically found in young adults and children, usually in the long bones of the lower extremity. Radiofrequency ablation (RFA) under computed tomography guidance is the standard of care for symptomatic osteoid osteomas. However, patients with osteoid osteoma of the hand or foot are often treated with open surgery because of the risk of injury to vascular and neural structures from RFA. This risk is more pronounced in pediatric patients because of the small lesion size and proximity of lesions to important neurovascular structures. Here, we present 2 pediatric patients, one with an osteoid osteoma in the hand and the other with an osteoid osteoma in the foot. In both patients, a 22-gauge, 2.5-mm active tip ablation probe was used. The smaller ablation volume achieved with this probe protected neighboring neurovascular structures while effectively ablating the osteoid osteoma nidus. Based on our success in these cases, we recommend the application of this method for cases in which neurovascular proximity to the osteoid osteoma lesion makes ablation challenging.

Creating an Intraoperative MRI Suite for the Musculoskeletal Tumor Center.

BACKGROUND: Altered anatomy in a previously irradiated surgical bed can make accurate localization of anatomic landmarks and local recurrence nearly impossible. The use of intraoperative MRI (iMRI) has been described in neurosurgical settings, but to our knowledge, no such description has been made regarding its utility for local recurrence localization in sarcoma surgery. CASE DESCRIPTION: A 58-year-old female presented after previously undergoing two previous resection and reresection procedures of a myxoid liposarcoma located adjacent to her proximal femoral vasculature. After postoperative radiation therapy, she was referred to our institution where she underwent two additional reexcisions of local recurrences during a 3-year span, eventually undergoing a regional rotational muscle flap for coverage. Two years after her third reexcision procedure, she presented with two additional, nonpalpable surgical-bed local recurrences. After converting an MRI bed and scanner to allow for proximal thigh imaging in an iMRI surgical suite, the patient underwent a successful resection that achieved negative margins. To date, she remains without evidence of disease at 37 months. LITERATURE REVIEW: Real-time iMRI in neurosurgical studies has shown a high rate of residual disease leading to immediate subsequent reexcision, thus lending to improved rates of negative margin resection. To our knowledge, this is the first example using iMRI technology to remove a recurrent soft tissue sarcoma that otherwise was clinically nonlocalizable. CLINICAL RELEVANCE: The use of an iMRI surgical suite can aid with identification of soft tissue nodules in conditions such as an altered tumor bed from prior resection and radiotherapy, which otherwise make recurrences difficult to localize. A team approach between administration, surgeons, and engineers is required to design and pragmatically implement the use of an MRI-compatible table extension to enhance existing iMRI surgical suite technology for extremity sarcoma resection procedures.

Throwing-related injuries of the subscapularis in professional baseball players.

OBJECTIVE: To describe the MR appearance of a series of throwing-related injuries to the subscapularis muscle-tendon complex among baseball players. MATERIALS AND METHODS: A retrospective review of MR scans of the shoulder in players from 1 professional baseball organization over the course of 5 years was performed to identify cases with findings suggestive of subscapularis injury. These findings were graded and the medical record was reviewed to assess clinical findings, treatment, and follow-up. Preinjury baseline measurements of arm external rotation at 90° of abduction were compared to measurements from a noninjured cohort to evaluate whether this measure is a risk factor for injury. RESULTS: A total of 133 MR scans of the shoulder were evaluated. Eleven of the scans demonstrated signal changes suggesting subscapularis injury; 10 of these 11 patients had clinical findings supporting a diagnosis of throwing-related subscapularis strain. There were four grade 1, four grade 2, and two grade 3 injuries. All injuries occurred in the inferior half of the subscapularis at the myotendinous junction. Risk of subscapularis injury increased with lower levels of dominant arm external rotation (odds ratio, 1.12; 95% CI, 1.07-1.21; p < 0.001). A threshold of dominant arm external rotation of <106° demonstrated sensitivity of 0.700 (95% CI, 0.392-0.897) and specificity of 0.951 (95% CI, 0.888-0.982) for subscapularis injury. CONCLUSION: Throwing-related subscapularis injuries occur in the inferior half of the muscle at the myotendinous junction. Our data suggest that there is an increased risk of these injuries with lower levels of dominant arm external rotation.

Osteochondroma of the fifth rib resulting in recurrent hemothorax.

A 48-year-old man presented with recurrent spontaneous hemothoraces, which ultimately were found to be secondary to a pedunculated costal osteochondroma causing vascular injury. After initially undergoing endovascular coil embolization, he ultimately required segmental rib resection containing the offending lesion for definite treatment. Although a few cases of symptomatic costal osteochondromas have been reported in the literature, as far as we know, no previous reports have provided direct radiologic confirmation of active bleeding or the role of angiographic intervention. In this report, we highlight the importance of CT angiography in establishing a direct link between an osteochondroma and recurrent hemothorax. We also discuss the diagnostic imaging challenges associated with this condition and the use of a multidisciplinary treatment strategy involving both angiographic and operative management.

Solitary C1 spinal osteochondroma causing vertebral artery compression and acute cerebellar infarct.

Osteochondroma is a common benign bone lesion, usually involving the long bones. Spinal involvement is rare. The clinical presentation of spinal osteochondroma varies according to the site of the lesion. The most common reported clinical presentation is secondary to encroachment of the lesion on the spinal canal or nerve roots. Less common presentations such as a palpable neck mass, dysphagia, sleep apnea, paralysis of left vocal cord or acute respiratory distress have been reported when the lesions compress the anatomic structures anteriorly. We describe a rare case of a young patient who presented with an emergent critical condition of acute cerebellar infarct as a result of vertebral artery compression caused by a solitary C1 spinal osteochondroma.

Pseudocyclops: two cases of ACL graft partial tears mimicking cyclops lesions on MRI.

Arthroscopic reconstruction of the anterior cruciate ligament (ACL) using autografts or allografts is a common surgical procedure, particularly in young athletes. Although the procedure has excellent success rates, complications such as mechanical impingement, graft rupture, and arthrofibrosis can occur, often necessitating additional surgery. Magnetic resonance (MR) imaging has become a valuable tool in evaluating complications after ACL reconstruction. We report two cases of ACL reconstruction complicated by arthroscopically proven partial graft tears. In both cases the torn anterior graft fibers were flipped into the intercondylar notch, mimicking anterior arthrofibrosis, i.e., a "cyclops lesion," on MR imaging. Careful review of the direction of graft fibers on MR imaging in the "pseudocyclops" lesions can help differentiate these partial tears from the fibrosis of a true cyclops. The "pseudocyclops" lesion is a previously undescribed MR imaging sign of partial ACL graft tear. Larger studies are required to determine the sensitivity and specificity of the sign, as well as the clinical importance of these partial graft tears.