Standardized reporting of spine and sacroiliac joints in axial spondyloarthritis MRI: from the ESSR-Arthritis Subcommittee.

OBJECTIVES: Apply a modified Delphi-based approach and produce a practical, radiology-specific set of definitions for interpretation and standardization of the multiple MRI findings in axial spondyloarthritis (ax-SpA), specifically to aid the general radiologist with a musculoskeletal interest, working with gold standard basic MRI protocols. MATERIALS AND METHODS: We report the results of a modified Delphi-based consensus of 35 experts from 13 countries in the Arthritis Subcommittee of the European Society of Musculoskeletal Radiology (ESSR). Seventeen definitions were created (i.e., nine for the spine and eight for the sacroiliac joint) and two Delphi rounds were conducted on an electronic database, collated and revised by the project leader with agreement. Group leads were appointed for each definition following the first round. Final definitions included only those that reached a consensus > 80%; if > 50% agreed on exclusion consensus, definitions were excluded. Final results have been shared during the Arthritis meeting at the Annual ESSR Congress. RESULTS: Fourteen definitions, eight for the spine and six for the sacroiliac joint were agreed for standardized reporting. Andersson's, anterior corner sclerotic and costovertebral joint inflammatory lesions of the spine, with active and non-active erosions, and fat metaplasia of the sacroiliac joint reaching the highest consensus (≥ 95%). More than 50% of the experts agreed to exclude joint space inflammation in the sacroiliac joint and tissue backfill. Syndesmophytes reached 76% agreement. CONCLUSIONS: Agreed definitions by expert radiologists using a modified Delphi process, should allow standardized actionable radiology reports and clarity in reporting terminology of ax-SpA. CLINICAL RELEVANCE STATEMENT: The proposed definitions will support reporting from musculoskeletal and general radiologists working with gold-standard basic MRI, improve confidence in lesion assessment, and standardize terminology to provide actionable reports on MRI in patients with ax-SpA. KEY POINTS: Experts applied a modified Delphi method to optimize the definitions of MRI findings of ax-SpA. After two Delphi rounds and one in-person meeting, fourteen definitions reached the agreement threshold. These consensus-based definitions will aid in actionable reporting specifically for the general radiologist with a musculoskeletal interest.

Introduction of a breast apparent diffusion coefficient category system (ADC-B) derived from a large multicenter MRI database.

OBJECTIVES: To develop an intuitive and generally applicable system for the reporting, assessment, and documentation of ADC to complement standard BI-RADS criteria. METHODS: This was a multicentric, retrospective analysis of 11 independently conducted institutional review board-approved studies from seven institutions performed between 2007 and 2019. Breast Apparent Diffusion coefficient (ADC-B) categories comprised ADC-B0 (ADC non-diagnostic), ADC-B1 (no enhancing lesion), and ADC-B2-5. The latter was defined by plotting ADC versus cumulative malignancy rates. Statistics comprised ANOVA with post hoc testing and ROC analysis. p values ≤ 0.05 were considered statistically significant. RESULTS: A total of 1625 patients (age: 55.9 years (± 13.8)) with 1736 pathologically verified breast lesions were included. The mean ADC (× 10-3 mm2/s) differed significantly between benign (1.45, SD .40) and malignant lesions (.95, SD .39), and between invasive (.92, SD .22) and in situ carcinomas (1.18, SD .30) (p < .001). The following ADC-B categories were identified: ADC-B0-ADC cannot be assessed; ADC-B1-no contrast-enhancing lesion; ADC-B2-ADC ≥ 1.9 (cumulative malignancy rate < 0.1%); ADC-B3-ADC 1.5 to < 1.9 (0.1-1.7%); ADC-B4-ADC 1.0 to < 1.5 (10-24.5%); and ADC-B5-ADC < 1.0 (> 24.5%). At the latter threshold, a positive predictive value of 95.8% (95% CI 0.94-0.97) for invasive versus non-invasive breast carcinomas was reached. CONCLUSIONS: The breast apparent diffusion coefficient system (ADC-B) provides a simple and widely applicable categorization scheme for assessment, documentation, and reporting of apparent diffusion coefficient values in contrast-enhancing breast lesions on MRI. CLINICAL RELEVANCE STATEMENT: The ADC-B system, based on diverse MRI examinations, is clinically relevant for stratifying breast cancer risk via apparent diffusion coefficient measurements, and complements BI-RADS for improved clinical decision-making and patient outcomes. KEY POINTS: • The breast apparent diffusion coefficient category system (ADC-B) is a simple tool for the assessment, documentation, and reporting of ADC values in contrast-enhancing breast lesions on MRI. • The categories comprise ADC-B0 for non-diagnostic examinations, ADC-B1 for examinations without an enhancing lesion, and ADC-B2-5 for enhancing lesions with an increasing malignancy rate. • The breast apparent diffusion coefficient category system may be used to complement BI-RADS in clinical decision-making.

Bone Remodeling in Osteoarthritis-Biological and Radiological Aspects.

Among available papers published on the given subject over the last century, various terms have been used as synonyms for one, now generally accepted-osteoarthritis, in some countries called "wear and tear" or "overload arthritis". The opsolent terms-hypertrophic arthritis, degenerative arthritis, arthritis deformans and osteoarthrosis-sought to highlight the dominant clinical signs of this ubiquitous, polymorph disease of the whole osteochondral unit, which by incidence and prevalence represents one of the leading chronic conditions that cause long-term pain and incapacity for work. Numerous in vitro and in vivo research resulted in broadened acknowledgments about osteoarthritis pathophysiology and pathology on both histological and cellular levels. However, the cause of osteoarthritis is still unknown and is currently the subject of a hypothesis. In this paper, we provide a review of recent findings on biological phenomena taking place in bone tissue during osteoarthritis to the extent useful for clinical practice. Choosing a proper radiological approach is a conditio sine qua non to the early diagnosis of this entity.

Second-Look Ultrasound Using Shear-Wave Elastography in MRI-Suspected Locoregional Recurrence of Breast Carcinoma.

PURPOSE: To investigate if second-look US using shear-wave elastography (SWE) can help to differentiate between benign and malignant changes in the postoperative breast after surgical treatment of breast carcinoma. MATERIALS AND METHODS: SWE and related sonographic features were reviewed in 90 female patients with a history of surgical treatment of breast carcinoma and a suspicious lesion detected on a follow-up MRI scan. A single experienced radiologist performed all second-look US exams with SWE measurements placing a circular region of interest measuring 2 mm in diameter over the stiffest part of the lesion. Tissue samples for histopathological analysis were obtained during the same US examination via core-needle biopsy. RESULTS: Out of 90 lesions, 39 were proven malignant on histopathological analysis. 50 % of malignant lesions had Elmax values ranging from 128 to 199 kPa, and 50 % of benign lesions had Elmax values ranging from 65 to 169 kPa. The cut-off value of 171.2 kPa for Elmax shows a sensitivity of 59 % and specificity of 78.4 % for carcinoma recurrence, area under the curve 0.706 (CI95 % 0.6-0.81), P = 0.001. In univariate logistic models, restricted diffusion and stiffness on SWE, Elmax > 171.2 kPa, were shown as significant recurrence predictors. In the multivariate model, restricted diffusion remains significant independent recurrence predictor. With a recurrence prevalence of 43 %, the test sensitivity is 95 % (CI95 % 81-99 %) and the specificity is 75 % (CI95 % 60-85 %). CONCLUSION: Stiffer lesions should be considered suspicious on second-look US in the postoperative breast and SWE can be a helpful tool in identifying malignant lesions, especially if this is related to restricted diffusion on MRI exam. Lesion stiffness, however, should not be considered as an independent predictor of lesion malignancy in the postoperative breast, because of benign changes that can appear stiff on SWE, as well as carcinoma recurrences that may appear soft.

Importance of shear-wave elastography in prediction of Achilles tendon rupture.

PURPOSE: It was demonstrated that about 6% of patients with a ruptured Achilles tendon experience the rupture of contralateral tendon in the future; the aim of this study was to estimate the risk for rupture of contralateral tendon in patients who underwent surgical reconstruction of ruptured Achilles tendon by using subjective questionnaires and shear-wave elastography. METHODS: Twenty-four patients who underwent surgical repair of the ruptured Achilles tendon and twelve age-matched healthy controls were examined with ultrasound SWE. Functional outcomes were assessed with American Orthopedic Foot and Ankle Society (AOFAS) scoring system and subjective rating system which we introduced and validated. RESULTS: The elasticity of injured tendon was markedly decreased (by 42%) compared to the contralateral tendon of the patient, as expected. Both AOFAS score and our novel subjective assessment scale positively correlate with ultrasound SWE values in ruptured Achilles tendons. The elasticity of contralateral Achilles tendons in patients was 23% lower than among healthy individuals. CONCLUSION: Irrespective of the lack of difference in the subjective feeling assessed by AOFAS, the contralateral tendon in the patients with reconstructed Achilles tendon has significantly lower stiffness than healthy individuals. Therefore, contralateral tendons in patients who suffered from rupture are more prone to future ruptures.

Comparison of sonoelastographic values of breast tissue with mammographically and ultrasonically assessed density: a cross-sectional study.

AIM: To determine the relationship between breast stiffness assessed with sonoelastography (elasticity) and breast tissue density assessed with mammography (MG) and ultrasound (US). METHODS: This cross-sectional study involved 100 women who underwent MG, gray-scale US, and shear-wave sonoelastography during 2013. Mammographic density was categorized into four groups and sonographic density into three groups according to Breast Imaging-Reporting and Data System criteria. The stiffness of breast parenchymal and adipose tissue in all breast quadrants was quantified by shear-wave sonoelastography. Mean elastographic estimates were compared with MG- and US-derived density estimates. RESULTS: Parenchymal and adipose tissue elasticity positively correlated with MG- and US-derived breast density (for parenchyma: for MG Kendall's tau b 0.522; Jonckheere-Terpstra test P<0.001 and for US Kendall's tau b 0.533; Jonckheere-Terpstra test P<0.001); the higher was the breast density on MG and US, the higher was the elastographic stiffness. CONCLUSION: Sonoelastographic breast stiffness strongly positively correlated with breast density. Thus, sonoelastography may have a potential for estimating the breast cancer risk, which allows a novel application of this technique in routine clinical practice.

WHAT CAN WE ACTUALLY SEE USING COMPUTER AIDED DETECTION IN MAMMOGRAPHY?

The main goal of this study was to compare the results of computer aided detection (CAD) analysis in screening mammography with the results independently obtained by two radiologists for the same samples and to determine the sensitivity and specificity of CAD for breast lesions. A total of 436 mammograms were analyzed with CAD. For each screening mammogram, the changes in breast tissue recognized by CAD were compared to the interpretations of two radiologists. The sensitivity and specificity of CAD for breast lesions were calculated using contingency table. The sensitivity of CAD for all lesions was 54% and specificity 16%. CAD sensitivity for suspicious lesions only was 86%. CAD sensitivity for microcalcifications was 100% and specificity 45%. CAD mainly 'mistook' glandular parenchyma, connective tissue and blood vessels for breast lesions, and blood vessel calcifications and axillary folds for microcalcifications. In this study, we confirmed CAD as an excellent tool for recognizing microcalcifications with 100% sensitivity. However, it should not be used as a stand-alone tool in breast screening mammography due to the high rate of false-positive results.

Evaluation of Breast Cancer Morphology Using Diffusion-Weighted and Dynamic Contrast-Enhanced MRI: Intermethod and Interobserver Agreement.

BACKGROUND: The capability of diffusion-weighted imaging (DWI) for morphological analysis of breast lesions is underexplored. PURPOSE: To evaluate the utility of DWI for assessment of morphological features of breast cancer by comparing DWI and dynamic contrast-enhanced (DCE) MRI findings to determine intermethod and interobserver agreement. STUDY TYPE: Retrospective. POPULATION: Seventy-eight women with pathohistologically proven breast cancer. FIELD STRENGTH/SEQUENCE: 1.5T. DWI and DCE images. ASSESSMENT: Diffusion-weighted and DCE images were placed in two separate case sets. Three radiologists, blinded to all other information, independently evaluated each case set on two separate occasions. Lesions were interpreted according to the fifth edition of the ACR BI-RADS lexicon. STATISTICAL ANALYSIS: Kappa (κ) statistics were calculated in order to assess intermethod and interobserver agreement. RESULTS: For values that attained statistical significance (P < 0.05), intermethod agreement ranged from fair (κ = 0.22) for nonmass internal patterns to significant (κ = 0.8) for lesion type. On DWI, interobserver agreement varied from fair (κ = 0.34) for mass shape to significant (κ = 0.75) for lesion type. On DCE MRI, interobserver agreement varied from fair (κ = 0.27) for irregular vs. spiculated mass margin to perfect (κ = 1) for circumscribed vs. noncircumscribed mass margin. DATA CONCLUSION: On the whole, there was moderate intermethod agreement. The values of interobserver agreement were mostly similar between DWI and DCE MRI. This suggests that DWI is applicable for morphological assessment of breast cancer, notwithstanding substantially inferior spatial resolution compared to DCE MRI. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:1381-1390.

SONOELASTOGRAPHIC FEATURES OF HIGH-RISK BREAST LESIONS AND DUCTAL CARCINOMA IN SITU - A PILOT STUDY.

The aim of this study was to evaluate the quantitative sonoelastographic values recorded on shear-wave sonoelastography (SWE) of high-risk breast lesions and ductal carcinoma in situ (DCIS). We retrospectively analyzed histopathologic and SWE data (quantitative maximum, minimum and mean stiffness, lesion-to-fat ratio (E-ratio), lesion size) of 228 women referred to our Department for core needle breast biopsy during a four-year period. Among 230 lesions, histopathologic findings showed 34 high-risk breast lesions and 29 DCIS, which were compared with 167 ductal invasive carcinomas. High-risk lesions had lower values of all sonoelastographic features than ductal in situ and invasive carcinoma, however, only E-ratio showed a statistically significant difference in comparison to DCIS (3.7 vs. 6, p<0.001). All sonoelastographic features showed significant difference between in situ and invasive carcinoma. There was a significant correlation between lesion size and stiffness (r=0.36; p<0.001). Stiffness measured by SWE is an effective predictor of the histopathologic severity of sonographically detectable breast lesions. Elasticity values of high-risk lesions are significantly lower than those of malignant lesions. Furthermore, we showed that along with the sonographic appearance, which in most cases shows typical microcalcifications, DCIS had significantly different elasticity parameters than invasive carcinoma.

Elastographic features of triple negative breast cancers.

OBJECTIVES: To evaluate shear-wave elastographic (SWE) features of triple negative breast cancers (TNBC) and determine useful discriminators from other types of invasive breast cancers. METHODS: SWE features of 26 TNBC were reviewed and compared to 32 non-TNBC. Qualitative SWE features of lesion colour appearance, shape and homogeneity were analysed. Quantitative features were measured: mean (El mean), maximum (El max) and minimum (El min) elasticity value of the stiffest portion of the mass, mean elasticity of the surrounding tissue (El mean surr) and lesion to fat elasticity ratio (E ratio). RESULTS: TNBC are more often regularly shaped (57.7 % vs. 6.2 %), while non-TNBC are more commonly red (93.7 % vs 42.3 %) and heterogeneous (68.7 % vs 42.3 %). The stiffness of TNBC is significantly lower compared to non-TNBC. The two groups could be distinguished on the basis of El max (p = 0.001), El mean (p = 0.001), El min (p = 0.001) and E ratio (p = 0.0017). Lesion to fat elasticity ratio in TNBC group was statistically significantly lower than in the non-TNBC control group (p = 0.009). CONCLUSIONS: TNBC often demonstrate benign morphological features, are softer on SWE and have a lower lesion to fat stiffness ratio compared to the other, more common types of invasive breast cancers. KEY POINTS: • TNBC often demonstrate benign morphological features on SWE. • TNBC present on elastography mostly as red, regularly shaped, heterogeneous lesions. • TNBC are less stiff compared to other invasive breast cancers. • TNBC have lower lesion to fat stiffness ratio than other breast cancers.

Shear-wave sonoelastographic features of invasive lobular breast cancers.

AIM: To evaluate shear-wave elastographic (SWE) and related gray-scale features of pure invasive lobular breast carcinoma (ILC) and compare them with invasive ductal breast cancers (IDC). METHODS: Quantitative SWE features of mean (El-mean), maximum (El-max), minimum (El-min) elasticity values of the stiffest portion of the mass, and lesion-to-fat elasticity ratio (E-ratio) were measured in 40 patients with pure ILC and compared with 75 patients with IDC. Qualitative gray-scale features of lesion size, echogenicity, orientation, and presence of distal shadowing were determined and compared between the groups. RESULTS: ILC were significantly larger than IDC (P=0.008) and exhibited significantly higher El-max (P=0.015) and higher El-mean (P=0.008) than IDC. ILC were significantly more often horizontally oriented, while IDC were significantly more often vertically oriented (P<0.001); ILC were significantly more often hyperechoic than IDC (P<0.001). Differences in stiffness between ILC and IDC determined by quantitative SWE parameters were present only in small tumors (≤1.5 cm in size), ie, small ILC had significantly higher El-max (P=0.030), El-mean (P=0.014), and El-min (P=0.045) than small IDC, while tumors larger than 1.5 cm had almost equal stiffness, without significant differences between the groups. CONCLUSION: Specific histopathologic features of ILC are translated into their qualitative sonographic and quantitative sonoelastographic appearance, with higher stiffness of small ILC compared to small IDC. Gray-scale and sonoelastographic features may help in diagnosing ILC.

Gray-scale and color duplex Doppler ultrasound of hand joints in the evaluation of disease activity and treatment in rheumatoid arthritis.

AIM: To evaluate the role of gray-scale and color duplex-Doppler ultrasound (CDUS) in diagnosis of changes of hand joints and assessment of treatment efficacy in patients with rheumatoid arthritis (RA) by comparing qualitative and quantitative US parameters with clinical and laboratory indicators of disease activity. METHODS: Ulnocarpal (UC), metacarpophalangeal (MCP), and proximal interphalangeal (PIP) joints in 30 patients with RA were examined by gray-scale and CDUS before and after six months of treatment. Morphologic and quantitative Doppler findings (synovial thickness, effusion quantity, vascularization degree, resistance index, velocities) were compared with clinical indicators of disease progression: disease activity score (DAS 28), Health Assessment Questionnaire (HAQ), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), and C reactive protein (CRP). RESULTS: Clinical indicators changed significantly after treatment: ESR from 38.1±22.4 mm/h to 27.8±20.9 mm/h (P=0.013), DAS 28 from 5.47±1.56 to 3.87±1.65 (P<0.001), and HAQ from 1.26±0.66 to 0.92±0.74 (P=0.030), indicating therapeutic effectiveness. In all MCP and UC joints we observed a significant change in at least one US parameter, in 6 out of 12 joints we observed a significant change in ≥2 parameters, and in 2 UC joints we observed significant changes in ≥3 parameters. The new finding was that the cut-off values of resistance index of 0.40 at baseline and of 0.55 after the treatment indicated the presence of active disease and the efficacy of treatment, respectively; also it was noticed that PIP joints can be omitted from examination protocol. CONCLUSION: Gray scale and CDUS are useful in diagnosis of changes in UC and MCP joints of patients with RA and in monitoring the treatment efficacy.

Comparison of multidetector-row computed tomography and duplex Doppler ultrasonography in detecting atherosclerotic carotid plaques complicated with intraplaque hemorrhage.

This study compared sensitivity and specificity of multidetector-row computed tomography and duplex Doppler ultrasonography in detecting atherosclerotic carotid plaques complicated with intraplaque hemorrhage. Carotid plaques from 50 patients operated for carotid artery stenosis were analyzed. Carotid endarterectomy was performed within one week of diagnostic evaluation. Results of multidetector-row computed tomography and duplex Doppler ultrasonography diagnostic evaluation were compared with results of histological analysis of the same plaque areas. American Heart Association classification of atherosclerotic plaques was applied for histological classification. Median tissue density of carotid plaques complicated with intraplaque hemorrhage was 14.7 Hounsfield units. Median tissue density of noncalcified segments of uncomplicated plaques was 54.3 Hounsfield units (p = 0.00003). The highest tissue density observed for complicated plaques was 31.8 Hounsfield units. Multidetector-row computed tomography detected plaques complicated with hemorrhage with sensitivity of 100% and specificity of 70.4%, with tissue density of 33.8 Hounsfield units as a threshold value. Duplex Doppler ultrasonography plaque analysis based on visual in-line classification showed sensitivity of 21.7% and specificity of 89.6% in detecting plaques complicated with intraplaque hemorrhage. Multidetector-row computed tomography showed a very high level of sensitivity and a moderate level of specificity in detecting atherosclerotic carotid plaques complicated with hemorrhage. Duplex Doppler ultrasonography plaque analysis based on visual in-line classification showed a low level of sensitivity and a moderate-high level of specificity in detecting atherosclerotic carotid plaques complicated with hemorrhage.

Noninvasive Fibrosis Assessment in Chronic Hepatitis C Infection: An Update.

Liver biopsy is historically the gold standard for liver fibrosis assessment of chronic hepatitis C patients. However, with the introduction and validation of noninvasive tests (NITs) to evaluate advanced fibrosis, and the direct-acting antiviral agents for treatment of chronic hepatitis C virus (HCV), the role of NITs have become even more complex. There is now need for longitudinal monitoring and elucidation of cutoff values for prediction of liver-related complication after sustained virological response. The aim of this report is to provide a critical overview of the various NITs available for the assessment of liver fibrosis in HCV patients.

A probable case of Hand-Schueller-Christian's disease in an Egyptian mummy revealed by CT and MR investigation of a dry mummy.

The challenging mission of paleopathologists is to be capable to diagnose a disease just on the basis of limited information gained by means of one or more paleodiagnostic techniques. In this study a radiologic, anthropologic and paleopathologic analysis of an ancient Egyptian mummy through X-rays, CT and MR was conducted. An Ancient Egyptian mummy ("Mistress of the house", Archeological Museum, Zagreb, Croatia) underwent digital radiography, computed tomography and magnetic resonance imaging employing 3-dimensional ultra-short-echo time (UTE) sequence, that allows to image ancient dry tissue. Morphological observations on the skull and pelvis, the stages of epiphyseal union and dental wear indicated that the remains are those of a young adult male. Multiple osseous lytic lesions were observed throughout the spine as well as on the frontal, parietal, and occipital bone, orbital wall and the sella turcica of the sphenoid. Considering the sex and age of the individual and the features of the lesions, the authors propose the diagnosis of Hand-Schueller-Christian's disease. This is the first study to have effectively used MR images in the differential diagnosis of a disease. It also confirmed the CT value in revealing central nervous system involvement just by detecting skeletal lesions. Although the mummy was previously dated to 3rd century B.C. based on the properties of the sarcophagi, the sex of the mummy suggests that it was most probably transferred into these sarcophagi in later times. The mummification techniques used and radiometric data (C14) dated it to 900-790. B.C.

Contribution of UltraFast™ Ultrasound and Shear Wave Elastography in the Imaging of Carotid Artery Disease.

Carotid artery disease is one of the main global causes of disability and premature mortality in the spectrum of cardiovascular diseases. One of its main consequences, stroke, is the second biggest global contributor to disability and burden via Disability Adjusted Life Years after ischemic heart disease. In the last decades, B-mode and Doppler-based ultrasound imaging techniques have become an indispensable part of modern medical imaging of carotid artery disease. However, they have limited abilities in carotid artery plaque and wall characterization and are unable to provide simultaneous quantitative and qualitative flow information while the images are burdened by low framerates. UltraFast™ ultrasound is able to overcome these obstacles by providing simultaneous quantitative and qualitative flow analysis information in high frame rates via UltraFast™ Doppler. Another newly developed ultrasound technique, shear wave elastography, is based on the visualization of induced shear waves and the measurement of the shear wave propagation speed in the examined tissues which enables real-time carotid plaque and wall analysis. These newly developed ultrasound modalities have potential to significantly improve workflow efficiency and are able to provide a plethora of additional imaging information of carotid artery disease in comparison to conventional ultrasound techniques.

Spontaneous pneumomediastinum, pneumothorax and subcutaneous emphysema: Radiological aspects of rare COVID-19 complications in 3 patients.

Spontaneous pneumomediastinum (SPM), pneumothorax (PNX) and subcutaneous emphysema are rare complications of COVID-19 pneumonia. In this paper we describe 3 cases of COVID-19 pneumonia complicated by SPM with or without PNX. Patient 1 was a 56-year-old woman whose medical history was significant for chronic leukemia. She presented with typical clinical signs of COVID-19 pneumonia and after 2 weeks of hospitalization she developed SPM and subcutaneous emphysema. The management of pneumomediastinum (PNM) was conservative and follow-up computed tomography showed resolution of PNM. Patient 2 was a 67-year-old man presenting with fever, cough and dyspnea. Computed tomography pulmonary angiography was performed after 2 weeks of hospitalization and showed bilateral peripheral consolidations together with massive PNM and right-sided PNX. Thoracic drainage catheter was inserted in his right chest. Despite all supportive care, the patient succumbed to illness. Patient 3 was a 74-year-old man who was admitted to our hospital with COVID-19 pneumonia and spontaneous right-sided PNX. A thoracic drainage catheter was inserted immediately and then removed after ten days which has led to progression of subcutaneous emphysema, PNX and newly diagnosed PNM. Patient was carefully monitored for the next 2 weeks. Follow-up chest x-ray showed regression of PNM and PNX. SPM, PNX and subcutaneous emphysema are rare complications of COVID-19 pneumonia. Increased alveolar pressure and diffuse alveolar injury in severe COVID-19 pneumonia may make the alveoli more prone to rupturing which leads to gas dissemination along the peribronchovascular sheath to the mediastinum. Most cases of SPM and PNX resolve with conservative management.

Giant Cell Tumor of the Distal Ulna: Multimodal Radiological Investigation of a Very Rare Location.

BACKGROUND Giant cell tumor is a rare tumor of mesenchymal origin. According to World Health Organization classification, it is considered a benign tumor with locally aggressive characteristics and the capacity to metastasize. The tumor typically occurs in the epiphyseal regions, most often of long bones after the completion of bone growth. The disease is characterized by severe pain and swelling of the affected area. Tumor growth is expansive but relatively slow. The tumor rarely metastasizes, but when it does, the lungs are primarily affected. CASE REPORT A 28-year-old man, otherwise healthy, presented with pain in the right wrist joint, limited range of motion, and spindle-shaped thickening/swelling in the same area, which he had noticed several months earlier. After a comprehensive diagnostic evaluation (wrist X-ray, computed tomography, magnetic resonance imaging, ultrasound-guided biopsy, and histopathological analysis), he was diagnosed with giant cell tumor of the right ulna. The tumor was surgically removed with good recovery, and the patient continued to be seen thereafter in regular followup. CONCLUSIONS The wide range of benign and malignant differential diagnostic entities requires a detailed diagnostic approach and comprehensive assessment, using different radiological modalities, as was done in this case. The final diagnosis was confirmed by histopathological analysis of core biopsy material.

Geographical and Temporal Distribution of Radiologists, Computed Tomography and Magnetic Resonance Scanners in Croatia.

The aim of the study was to analyse the temporal and geographic distribution of radiologists, computed tomography and magnetic resonance scanners in Croatia. In this observational study we estimated radiologists' number per 100,000 population for 1997, 2006, and 2017 and compared private and public CT and MR scanners between 2011 and 2018. We analyzed the availability of radiologists and scanners, and the relationship between the radiological workforce and economic strength among counties. The workforce increased significantly from 1997 to 2017 and was associated with economic strength categories in 2017. In 2018, there were more CT scanners in the public sector, while MR scanners were distributed evenly. In 2011, there was similar distribution of CT and MR between sectors, while in 2018 there were significantly more public CT scanners. Counties with a medical school had significantly more radiologists and MR scanners. The high-to-low ratios per CT and MR were 11 and 8.2, suggesting inequality of health care. Croatia significantly increased its radiological workforce; however, cross-county inequality remained. Counties with higher economic strength and medical schools have better availability of radiologists and equipment. To ensure the sustainable activity of the health care system, a precise estimate of supply and demand of radiology services is needed.