Diagnostic performance of tomosynthesis for evaluation of bone tumors and tumor-like lesions: a comparison with radiography.

BACKGROUND: Even though radiologic diagnosis of bone tumors and tumor-like lesions is usually based on radiographs, radiographically faint imaging features sometimes remain challenging due to overlapping anatomical structures. PURPOSE: To compare tomosynthesis with radiography for the evaluation of bone tumors and tumor-like lesions. MATERIAL AND METHODS: Forty-seven bone tumors and tumor-like lesions were assessed with radiographs and tomosynthesis images. Two radiologists independently analyzed imaging features of lesions, including margin, periosteal reaction, cortical thinning, matrix mineralization, cortical destruction (such as pathologic fracture), and extraosseous soft-tissue extension. Computed tomography (CT) imaging was used as a reference method. Diagnostic performances of radiography and tomosynthesis were analyzed and compared based on sensitivity, specificity, accuracy, positive predictive value, and negative predictive value. Effective radiation dose was compared among the three imaging modalities by phantom studies. RESULTS: Inter-observer variability (kappa value) for imaging features was slight to moderate on radiography (0.167-0.588), whereas it was nearly perfect on tomosynthesis (0.898-1.000) except for extraosseous soft-tissue extension (0.647 vs. 0.647). Tomosynthesis showed significantly higher sensitivity than radiography in evaluating the margin for bone tumors or tumor-like lesions (1.00 vs. 0.85; P = 0.016), and significantly higher accuracy than radiography in evaluating the margin and matrix mineralization for those (1.00 vs. 0.85; P = 0.016 and 0.91 vs.0.77; P = 0.023, respectively). In phantom studies, mean effective radiation doses were highest in order of CT, tomography, and radiography. CONCLUSION: Tomosynthesis increases sensitivity and accuracy of the margin as well as accuracy of the matrix mineralization of bone tumors and tumor-like lesions compared to radiography.

Distant migration of gel filler: imaging findings following breast augmentation.

Recently, many attempts have been made to use injectable materials in the subcutaneous fat layer anywhere in the body, including the breast and face, for cosmetic purposes. A 56-year-old woman presented with multiple palpable lumps without tenderness or skin color changes on the anterior and lateral chest and the abdominal walls. Magnetic resonance imaging showed fluid-like collections without surrounding soft tissue inflammatory changes in the chest wall, abdominal wall, and deeper within the abdomen. The lesions penetrated the peritoneum and were observed adjacent to the liver dome. Ultrasonography also showed hypoechogenicity suggestive of fluid collection in the left axilla and trunk. The differential diagnosis based on radiologic findings included parasite manifestation, non-specific inflammatory conditions, and chronic granulomatous infections such as tuberculosis or non-tuberculous mycobacterial infections. However, these conditions are usually accompanied by changes in the adjacent subcutaneous fat layers, but our patient did not show any other abnormalities in the adjacent soft tissue. After biopsy and aspiration analysis, the patient was found to have a history of filler injection for breast augmentation approximately 17 years prior. It is often difficult to make a differential diagnosis without detailed knowledge of the patient's medical history. Here we describe a rare case of distant migration of the filler to the axilla, chest wall, abdominal wall, and peritoneum following breast augmentation with filler injection. Knowledge of the radiologic characteristics and migration patterns of gel fillers and their related complications is useful for making an accurate diagnosis.

Myositis Ossificans with Aneurysmal Bone Cystic Changes at the Thoracic Paraspinal Region: A Case Report.

Myositis ossificans (MO) is a benign heterotopic bone formation in muscle or soft tissue. It is a self-limiting disease that is usually initiated by trauma and often occurs in the extremities of the body. Here we report a rare case of traumatic myositis ossificans caused by unusual trauma (extracorporeal shock wave therapy) at thoracic paraspinal muscles. After a needle biopsy, the lesion increased in size, and the patient's symptoms worsened. Malignant soft tissue tumors such as osteosarcoma should be differentiated, so excision of the mass was performed. The final diagnosis was MO with aneurysmal bone cystic change. This case is a very rare form of MO that showed an unusual cause, location, clinical course, and pathologic result on follow-up. This can be an instructive case for radiologists as it is a common disease entity with unusual manifestations.

Emphysema Quantification Using Ultra-Low-Dose Chest CT: Efficacy of Deep Learning-Based Image Reconstruction.

Background and Objectives: Although reducing the radiation dose level is important during diagnostic computed tomography (CT) applications, effective image quality enhancement strategies are crucial to compensate for the degradation that is caused by a dose reduction. We performed this prospective study to quantify emphysema on ultra-low-dose CT images that were reconstructed using deep learning-based image reconstruction (DLIR) algorithms, and compared and evaluated the accuracies of DLIR algorithms versus standard-dose CT. Materials and Methods: A total of 32 patients were prospectively enrolled, and all underwent standard-dose and ultra-low-dose (120 kVp; CTDIvol < 0.7 mGy) chest CT scans at the same time in a single examination. A total of six image datasets (filtered back projection (FBP) for standard-dose CT, and FBP, adaptive statistical iterative reconstruction (ASIR-V) 50%, DLIR-low, DLIR-medium, DLIR-high for ultra-low-dose CT) were reconstructed for each patient. Image noise values, emphysema indices, total lung volumes, and mean lung attenuations were measured in the six image datasets and compared (one-way repeated measures ANOVA). Results: The mean effective doses for standard-dose and ultra-low-dose CT scans were 3.43 ± 0.57 mSv and 0.39 ± 0.03 mSv, respectively (p < 0.001). The total lung volume and mean lung attenuation of five image datasets of ultra-low-dose CT scans, emphysema indices of ultra-low-dose CT scans reconstructed using ASIR-V 50 or DLIR-low, and the image noise of ultra-low-dose CT scans that were reconstructed using DLIR-low were not different from those of standard-dose CT scans. Conclusions: Ultra-low-dose CT images that were reconstructed using DLIR-low were found to be useful for emphysema quantification at a radiation dose of only 11% of that required for standard-dose CT.

Imaging Characterization of Non-Rheumatoid Retro-Odontoid Pseudotumors: Comparison with Atlantoaxial Manifestation of Rheumatoid Arthritis.

Backgroundand Objectives: To date, imaging characterization of non-rheumatic retro-odontoid pseudotumors (NRROPs) has been lacking; therefore, NRROPs have been confused with atlantoaxial joint involvement of rheumatoid arthritis (RA). It is important to differentiate these two disease because the treatment strategies may differ. The purpose of this study is to characterize imaging findings of NRROPs and compare them with those of RA. Material and Methods: From January 2015 to December 2019, 27 patients (14 women and 13 men) with NRROPs and 19 patients (15 women and 4 men) with RA were enrolled in this study. We evaluated various imaging findings, including atlantoaxial instability (AAI), and measured the maximum diameter of preodontoid and retro-odontoid spaces with magnetic resonance imaging (MRI) and computed tomography (CT). Results: Statistical significance was considered for p < 0.05. AAI was detected in eight patients with NRROPs and in all patients with RA (p < 0.0001). Seventeen patients with NRROPs and six patients with RA showed spinal cord compression (p = 0.047). Compressive myelopathy was observed in 14 patients with NRROPs and in 4 patients with RA (p = 0.048). Subaxial degeneration was observed in 25 patients with NRROPs and in 9 patients with RA (p = 0.001). Moreover, C2-3 disc abnormalities were observed in 11 patients with NRROPs and in 2 patients with RA (p = 0.02). Axial and longitudinal diameter of retro-odontoid soft tissue and preodontoid and retro-odontoid spaces showed significant differences between NRROP and RA patients (p < 0.0001). Furthermore, CT AAI measurements were differed significantly between NRROP and RA patients (p < 0.05). Conclusions: NRROPs showed prominent retro-odontoid soft tissue thickening, causing compressive myelopathy and a high frequency of subaxial and C2-3 degeneration without AAI.

Protein phosphatase magnesium-dependent 1A induces inflammation in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a highly inflammatory autoimmune disease. Although proinflammatory cytokines, including tumor necrosis factor (TNF) and interleukin (IL)-6, play a key role in the pathogenesis of RA, the causes of chronic inflammation are not fully understood. Here, we report that protein phosphatase magnesium-dependent 1A (PPM1A) levels were increased in RA synovial fluid compared with osteoarthritis (OA) synovial fluid and positively correlated with TNF levels. In addition, PPM1A expression was increased in synovial tissue from RA patients and joint tissue from a mouse model of arthritis. Finally, extracellular PPM1A induced inflammation by stimulating macrophages to produce TNF through toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein 88 (MyD88) signaling pathway. Our findings suggest that extracellular PPM1A may contribute to the pathogenesis of RA by functioning as a damage-associated molecular pattern (DAMP) to induce inflammation.

Bone marrow edema in non-traumatic hip: high accuracy of dual-energy CT with water-hydroxyapatite decomposition imaging.

OBJECTIVES: To evaluate the diagnostic performance of dual-energy CT with water-hydroxyapatite (HAP) imaging for bone marrow edema in patients with non-traumatic hip pain. METHODS: Forty patients (mean age, 58 years; 16 male and 24 female) who underwent rapid kVp-switching dual-energy CT and MRI within 1 month between April 2018 and February 2019 with hip pain but no trauma were enrolled. Two radiologists retrospectively evaluated 80 hip joints for the presence, extent (femoral head involved, head and neck, and head to intertrochanter), and severity (mild edema, moderate, severe) of bone marrow edema on dual-energy water-HAP images. Water mass density (mg/cm3) on water-HAP images was determined with region of interest-based quantitative analysis. MRI served as the standard of reference. RESULTS: Sensitivity, specificity, and accuracy of readers 1 and 2 for the identification of bone marrow edema in water-HAP images were 85% and 85%, 93% and 73%, and 89% and 79%, respectively. The area under the receiver operating characteristic curve was 0.96 for reader 1 and 0.91 for reader 2 for differentiation of the presence of edema from no edema. The optimal water mass density to classify the presence of edema for reader 1 was 951 mg/cm3 with 93% sensitivity and 93% specificity and for reader 2 was 957 mg/cm3 with 80% sensitivity and 80% specificity. The more severe the edema, the higher was the mean water density value (p < 0.035). CONCLUSION: Dual-energy water-HAP images showed good diagnostic performance for bone marrow edema in patients with non-traumatic hip pain. KEY POINTS: • Dual-energy water-HAP imaging depicts bone marrow edema in patients with non-traumatic hip pain and may serve as an alternative to MRI in select patients. • A cutoff value of 951 mg/cm3mean water mass density results in 93% sensitivity and 93% specificity for the detection of bone marrow edema. • The more severe the bone marrow edema, the higher the mean water density value.

Not All Green Is Tophi: The Importance of Optimizing Minimum Attenuation and Using a Tin Filter to Minimize Clumpy Artifacts on Foot and Ankle Dual-Energy CT.

OBJECTIVE. The clumpy artifact has a high misdiagnosis rate, but the artifact has not been well studied. The aims of this study were to evaluate the frequency and location of clumpy artifacts, the rate of misdiagnosis of clumpy artifacts as gout, and the effects of raising the minimum attenuation value and using a selective photon shield in dual-energy CT (DECT). MATERIALS AND METHODS. Forty patients without gout who underwent foot and ankle DECT were enrolled in this study. Images in both sets were randomly assigned a minimum attenuation of 130 HU or 150 HU. Three radiologists independently checked all images for presence, volume, and location of green color-coded pixelation and graded their findings according to a 4-point confidence scale, frequency, and volume. Misdiagnosis rate and misdiagnosis score were compared using the Wilcoxon signed rank and McNemar tests. RESULTS. In set 1, the frequency of clumpy artifacts in DECT with the minimum attenuation set to 130 HU and 150 HU were 81% and 68%, respectively. For all three readers, the misdiagnosis rate and misdiagnosis score decreased when changing the minimum attenuation from 130 HU to 150 HU. In set 2, with the minimum attenuation set to 130 HU, the frequency of the clumpy artifact was 44%; with the minimum attenuation set to 150 HU, no clumpy artifacts were seen. CONCLUSION. Clumpy artifacts occurred frequently in DECT without a tin filter. Setting the minimum attenuation to the higher value of 150 HU reduced the frequency of clumpy artifacts, and adding a tin filter to DECT greatly reduced their occurrence.

Diagnostic performance of diffusion-weighted (DWI) and dynamic contrast-enhanced (DCE) MRI for the differentiation of benign from malignant soft-tissue tumors.

BACKGROUND: A wide range of specificity values for the differentiation of benign and malignant soft-tissue tumors show the limitations of conventional MRI features. The data obtained by quantitative analysis of diffusion-weighted image (DWI) and dynamic contrast-enhanced (DCE) MRIs would provide more objective results, especially in terms of cellularity and perfusion. PURPOSE: To evaluate the diagnostic efficacies of DWI and DCE MRI for the differentiation of malignant and benign soft-tissue tumors. STUDY TYPE: Retrospective. SUBJECTS: In all, 136 patients (68 females, 68 males; age range 18-86 years, mean age 57.2 years) with soft-tissue tumors. FIELD STRENGTH/SEQUENCE: 3 T, DWI, DCE. ASSESSMENT: Tumor sizes, margins, locations, the presence of involvement in bone or neurovascular bundle, peritumoral edema, heterogeneity, and tumor necrosis were investigated on conventional MR images. On DWIs, visual signal drops were assessed and ADC (apparent diffusion coefficient) values were measured. Ktrans , Kep , Ve , and iAUC values, and time-concentration curve (TCC) types were determined using DCE images. STATISTICAL TESTS: The data were statistically analyzed to determine the abilities to differentiate benign and malignant tumors using the chi-square test, two-sample t-test, and receiver operating characteristic (ROC) analysis. RESULTS: Seventy-three cases were malignant and 63 benign. Age (mean ages of benign/malignant tumors, 51.75/61.86 years; P = 0.0002) and gender (F:M = 40:23 [benign], F:M = 28:45 [malignant], P = 0.003) influenced the distinction between benign and malignant. Sizes, margins, neurovascular bundle involvement, peritumoral edema, and heterogeneity of the tumors on conventional MR images and DCE parameters (Ktrans , Kep , Ve , and iAUC, and TCC plots) obtained from focal region of interest within a narrow volume of interest significantly differentiated benign and malignant lesions (all P < 0.0001, except Ve [P = 0.0004]). For DWI with ADC mapping, all ADC values and visually signal drops were also significant (P < 0.0001). DATA CONCLUSION: DWI and DCE-MRI and derived variables were significantly helpful in discriminating benign and malignant soft-tissue tumors complementary to conventional MRI. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:798-809.

Muscular sarcoidosis involving the chest and abdominal walls: case report with MR imaging.

Sarcoidosis is an inflammatory disorder that is characterized by the presence of noncaseating granulomas in tissues, involving many organs and tissues. Extra-pulmonary, especially muscular sarcoidosis is a rare condition. The most common location of the muscular sarcoidosis is known to be the proximal muscles of the extremities; however, there have been no cases of diffuse involvement of the chest and abdominal wall muscles. Here, we report a rare muscular sarcoidosis with infiltrative pattern in the chest and abdominal wall muscles and describe the MR imaging findings that were mistaken as lymphoma at initial diagnosis. Although our case did not show characteristic MR findings of muscular sarcoidosis, clinicians or radiologists who are aware of these imaging features can perform early systemic survey for sarcoidosis. Also muscle biopsy is very important to confirm the sarcoidosis and distinguish it from other tumors.

Biologic Profiles of Invasive Breast Cancers Detected Only With Digital Breast Tomosynthesis.

OBJECTIVE: The purpose of this study was to analyze the clinicopathologic and immunohistochemical features of invasive breast cancers detected only with digital breast tomosynthesis (DBT), compared with those of cancers detected with both DBT and full-field digital mammography (FFDM). MATERIALS AND METHODS: The medical records of 261 women (108 without and 153 with symptoms) with invasive breast cancers who underwent FFDM and DBT between April 2015 and June 2016 were retrospectively reviewed. To assess detectability, all DBT and FFDM images were reviewed independently by three radiologists blinded to clinicopathologic information. The reference standard was established by an unblinded consensus review of all images. Clinicopathologic and immunohistochemical features were analyzed according to the detectability status. RESULTS: Of the 261 cancers, 223 (85.4%) were detected with both DBT and FFDM (both-detected group). Twenty-four cancers (9.2%) not detected with FFDM (DBT-only group) were classified by DBT as a mass (58.3%), architectural distortion (33.3%), or asymmetry (8.3%). The remaining 14 cancers (5.4%) were not detected with either DBT or FFDM (both-occult group). On multivariate analysis, a dense breast parenchyma (p = 0.007), small tumor size (≤ 2 cm; p = 0.027), and luminal A-like subtype (estrogen receptor positive or progesterone receptor positive or both, human epidermal growth factor receptor 2 negative, and Ki-67 expression < 14%; p = 0.008) were significantly associated with the DBT-only group. For 108 screening-detected cancers, a dense breast parenchyma (p = 0.007) and luminal A-like subtype (p = 0.008) also maintained significance. CONCLUSION: The addition of DBT to FFDM in screening would aid in the detection of less-aggressive subtypes of invasive breast cancers in women with dense breasts.

Clinical efficacy of motion-insensitive imaging technique with deep learning reconstruction to improve image quality in cervical spine MR imaging.

OBJECTIVE: To demonstrate that a T2 periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique using deep learning reconstruction (DLR) will provide better image quality and decrease image noise. METHODS: From December 2020 to March 2021, 35 patients examined cervical spine MRI were included in this study. Four sets of images including fast spin echo (FSE), original PROPELLER, PROPELLER DLR50%, and DLR75% were quantitatively and qualitatively reviewed. We calculated the signal-to-noise ratio (SNR) of the spinal cord and sternocleidomastoid (SCM) muscle and the contrast-to-noise ratio (CNR) of the spinal cord by applying region-of-interest at the spinal cord, SCM muscle, and background air. We evaluated image noise with regard to the spinal cord, SCM, and back muscles at each level from C2-3 to C6-7 in the 4 sets. RESULTS: At all disc levels, the mean SNR values for the spinal cord and SCM muscles were significantly higher in PROPELLER DLR50% and DLR75% compared to FSE and original PROPELLER images (P < .0083). The mean CNR values of the spinal cord were significantly higher in PROPELLER DLR50% and DLR75% compared to FSE at the C3-4 and 4-5 levels and PROPELLER DLR75% compared to FSE at the C6-7 level (P < .0083). Qualitative analysis of image noise on the spinal cord, SCM, and back muscles showed that PROPELLER DLR50% and PROPELLER DLR75% images showed a significant denoising effect compared to the FSE and original PROPELLER images. CONCLUSION: The combination of PROPELLER and DLR improved image quality with a high SNR and CNR and reduced noise. ADVANCES IN KNOWLEDGE: Motion-insensitive imaging technique (PROPELLER) increased the image quality compared to conventional FSE images. PROPELLER technique with a DLR reduced image noise and improved image quality.

Comprehensive evaluation of artifact reduction and tissue recovery effects of metal artifact reduction technique based on full-reference metric.

For the comprehensive evaluation of metal artifact reduction (MAR) technique, not only the removal of metal artifacts but also the evaluation of the area restored by MAR is required. We propose a method to comprehensively evaluate the effect by MAR in this study. We have conducted the computed tomography scan to acquire both the evaluation image and the reference image for the full-reference based evaluation. The evaluation image and reference image were reconstructed into 24 image sets according to the tube potentials, image reconstruction method, and use of the MAR technique. Images of two different positions were selected according to the distance from metal and material (bone, tissue) distribution, and bone and tissue were automatically segmented in both evaluation and reference images. The values of full width at half the maximum (FWHM) and centroid were extracted after Gaussian modeling of each segmented region. Then, we computed four evaluation metrics (FWHMNM: non-MAR to non-metal ratio of FWHM, FWHMM: MAR to non-metal ratio of FWHM, CENTNM: non-MAR to non-metal ratio of centroid, CENTM: MAR to non-metal ratio of centroid), and the MAR image and non-MAR image were compared. The overlap ratio automatically segmented from the evaluation image and reference image were position 1 (bone: 99.61%, tissue: 99.23%) with 80 kVp, position 1 (bone: 99.32%, tissue: 99.56%) with 120 kVp, position 2 (bone: 99.20%, tissue: 99.73%) with 80 kVp, and position 2 (bone: 99.23%, tissue: 99.67%) with 120 kVp. The FWHMNM showing the change of image pixel value by metal artifact was calculated as (bone: 1.32-1.46, tissue: 1.08-1.16) at 80 kVp and (bone: 1.19-1.27, tissue: 1.02-1.05) at 120 kVp. More metal artifacts occurred at 80 kVp tube potential. Regardless of the tube potential and image reconstruction method, the MAR showed an overall artifact reduction effect (1 < FWHMM < FWHMNM). However, distortion of pixel values occurred due to the MAR in regions where metal artifacts were high in proximity to metal (1 < FWHMNM < FWHMM). Overall, the average value of the medium was maintained (CENTM: 0.98-1.03) after MAR application, but there was a change of image value in region around the metal (CENTM: 0.97-1.11). In this study, we propose a new method to evaluate the effect of metal artifacts and MAR technique using full-reference based method. Metal artifacts, effect of MAR technique, and side-effect caused by MAR technique were quantitatively analyzed through proposed method. There are some limitations in applying it to clinical imaging since our method is a reference-based evaluation. However, our experimental results were important for understanding the effects of the MAR technique and its functional properties.

Malignant Tenosynovial Giant Cell Tumor Presenting as an Extra-Articular Superficial Soft-Tissue Mass in a Knee.

Malignant tenosynovial giant cell tumor (TsGCT) is a rare disease that can arise as a recurrent lesion or co-exist with a benign TsGCT lesion. Here we report a rare case of malignant TsGCT in a 73-year-old male with a history of lymphoma. The tumor appeared as a superficial soft-tissue mass in the subcutaneous fat tissue of the left knee.

Clumpy artifacts can be differentiated from tophi with DECT: comparison between gout-free and gouty patients.

OBJECTIVES: To accurately differentiate clumpy artifacts from tophi with foot and ankle DECT. METHODS AND MATERIALS: In session 1, 108 clumpy artifacts from 35 patients and 130 tophi images from 25 patients were analyzed. Reviewers classified green pixelation according to anatomic location, shape (linear, stippled, angular, oval), and height and width ratio. In session 2, green pixelation confined to the tendon was evaluated (shape, height and width ratio, occupied area in the tendon, accompanied peritendinous green pixelation). RESULTS: In session 1, while tophi were noted at various locations, almost all clumpy artifacts were located at the tendon (99%, p < 0.0001). Most clumpy artifacts were linear, stippled, and wide, while most tophi were angular and oval (p < 0.05). In session 2, the shape of green pixelation from clumpy artifacts and tophi was significantly different (p < 0.0001) and most clumpy artifacts occupied less than 50% of the tendon (p = 0.02), and most tophi were accompanied by peritendinous green pixelation (p < 0.0001). Univariant logistic regression showed that tophi were significantly correlated with peritendinous deposits, angular and oval shape, and more than 50% of the tendon (p < 0.05). CONCLUSION: Clumpy artifacts can be differentiated from tophi in DECT. Clumpy artifacts typically are located in the tendon with a linear or stippled shape, wide, and less than 50% of a tendon's cross-section. Tophi, on the other hand, typically are oval, larger than 50% of the tendon's cross-section, and associated with adjacent peritendinous green pixelation. ADVANCES IN KNOWLEDGE: Clumpy artifacts can be differentiated from tophi in image findings by their location and shape.

Malignant melanotic nerve sheath tumors in the spinal canal of psammomatous and non-psammomatous type: Two case reports.

BACKGROUND: A malignant melanotic nerve sheath tumor (MMNST), previously known as a melanotic schwannoma, is a rare variant of a peripheral nerve sheath tumor composed of Schwann cells with melanotic differentiation. Only a few reports of spinal MMNST have been reported. CASE SUMMARY: In the first case, a 58-year-old woman presented with a history of low back pain and paresthesia. Magnetic resonance imaging (MRI) and computed tomography (CT) of the lumbar spine revealed an intradural extramedullary mass lesion with amorphous linear calcification. Complete tumor resection was performed and histological examination revealed a psammomatous melanotic schwannoma. In the second case, a 72-year-old man presented with low back pain and paresthesia. MRI of the thoracolumbar spine revealed an intramedullary mass lesion at the T11 vertebral body level. The mass lesion was hypointense on T2WI and hyperintense on T1WI. Tumor resection was performed and the histologic result was melanotic schwannoma. CONCLUSION: MMNST should be considered in the differential diagnosis when calcification or melanin is seen in an intradural spinal tumor.

Erratum: Transiting Nerve Rootlet Abnormalities on MRI after Lumbar Laminectomy: Associations with Persistent Postoperative Pain.

This corrects the article on p. 225 in vol. 22, PMID: 32901462.

Radiologic findings of adult pelvis and appendicular skeletal Langerhans cell histiocytosis in nine patients.

OBJECTIVE: The purpose of this article was to evaluate the radiologic findings of adult pelvis and appendicular skeletal Langerhans cell histiocytosis (LCH), emphasizing the CT and MR findings. MATERIALS AND METHODS: The images of nine patients with pathologically proven LCH (five men and four women; mean age, 37.11 years) were retrospectively reviewed. Imaging analysis was confined to the long and flat bones. CT scans were performed in five patients and MR imaging was performed in eight. Images were assessed for the following features on CT and MRI: the location and number of lesions; the presence of cortical destruction, endosteal scalloping, and a periosteal reaction on CT or MRI; the margin of soft tissue masses, the presence of bone marrow edema, and a "budding" appearance on MRI; and the presence of sclerotic margins or septations on CT. RESULTS: The involved skeletal sites were the pelvis (seven), femurs (five), humeri (two), tibias (two), fibula (one), clavicle (one), scapula (one), and sternum (one). Endosteal scalloping, a periosteal reaction, and a budding appearance were common on MRI or CT images. Although cortical destruction and the soft tissue lesion formation were rare, soft tissue masses had well-defined margins. CONCLUSIONS: Endosteal scalloping and a budding appearance with a periosteal reaction on CT and MRI may be helpful signs for differentiation of LCH from malignant tumors in adults.

Imaging characteristics of intradural disc herniation: A comparison with large disc extrusion.

OBJECTIVE: To compare the computed tomography (CT) and magnetic resonance imaging (MRI) findings of lumbar intradural disc herniation (IDH) and disc extrusion mimicking IDH. MATERIALS AND METHODS: Between January 2015 and August 2018, 32 with surgically confirmed IDH or disc extrusion mimicking IDH were included. Age, sex, symptoms, herniated disc level, history of discectomy at the same site, and operative findings were investigated through the medical records. We evaluated the direction, type, migration, margin, and shape of disc herniation, the presence of an abrupt discontinuity of the posterior longitudinal ligament (PLL), Y-sign of ventral dura, disc material beyond the PLL, and disc calcification or ossification. In addition, maximum herniated disc diameter to central canal diameter (MHDD/CCD) ratios were calculated. RESULTS: Twelve patients (8 males, 4 females; mean age 53.3 [21-83] years) were surgically confirmed to have lumbar IDH and 20 (11 males, 9 females; mean age 52 [19-78] years) had disc extrusion mimicking lumbar IDH. Margins and beak-like shapes of herniated discs, abrupt discontinuity of the PLL, Y-sign of ventral dura, disc material beyond the PLL, calcification or ossification of herniated discs, and MHDD/CCD ratios were significantly different in the IDH and non-IDH groups (p < 0.05). CONCLUSION: Imaging findings of an ill-defined margin, a beak-like shape, herniated disc calcification or ossification, abrupt PLL discontinuity, Y-sign of ventral dura, disc material beyond the PLL and a high MHDD/CCD ratio were found to predict the presence of IDH.

Transiting Nerve Rootlet Abnormalities on MRI after Lumbar Laminectomy: Associations with Persistent Postoperative Pain.

OBJECTIVE: To determine whether changes in the transiting nerve rootlet or its surroundings, as seen on MRI performed after lumbar hemilaminectomy, are associated with persistent postoperative pain (PPP), commonly known as the failed back surgery syndrome. MATERIALS AND METHODS: Seventy-three patients (mean age, 61 years; 43 males and 30 females) who underwent single-level partial hemilaminectomy of the lumbar spine without postoperative complications or other level spinal abnormalities between January 2010 and December 2018 were enrolled. Two musculoskeletal radiologists evaluated transiting nerve rootlet abnormalities (thickening, signal alteration, distinction, and displacement), epidural fibrosis, and intrathecal arachnoiditis on MRI obtained one year after the operations. A spine surgeon blinded to the radiologic findings evaluated each patient for PPP. Univariable and multivariable analyses were used to evaluate the association between the MRI findings and PPP. RESULTS: The presence of transiting nerve rootlet thickening, signal alteration, and ill-distinction was significantly different between the patients with PPP and those without, for both readers (p ≤ 0.020). Conversely, the presence of transiting nerve rootlet displacement, epidural fibrosis, and intrathecal arachnoiditis was not significantly different between the two groups (p ≥ 0.128). Among the above radiologic findings, transiting nerve rootlet thickening and signal alteration were the most significant findings in the multivariable analyses (p ≤ 0.009). CONCLUSION: On MRI, PPP was associated with transiting nerve rootlet abnormalities, including thickening, signal alterations, and ill-distinction, but was not associated with epidural fibrosis or intrathecal arachnoiditis. The most relevant findings were the nerve rootlet thickening and signal alteration.