MRI of the sacroiliac joints in spondyloarthritis: the added value of intra-articular signal changes for a 'positive MRI'.

OBJECTIVE: To determine if intra-articular signal changes at the sacroiliac joint space on MRI have added diagnostic value for spondyloarthritis, when compared to bone marrow edema (BME). MATERIALS AND METHODS: A retrospective study was performed on the MRIs of sacroiliac joints of 363 patients, aged 16-45 years, clinically suspected of sacroiliitis. BME of the sacroiliac joints was correlated to intra-articular sacroiliac joint MR signal changes: high T1 signal, fluid signal, ankylosis and vacuum phenomenon (VP). These MRI findings were correlated with final clinical diagnosis. Sensitivity (SN), specificity (SP), likelihood ratios (LR), predictive values and post-test probabilities were calculated. RESULTS: BME had SN of 68.9%, SP of 74.0% and LR+ of 2.6 for diagnosis of spondyloarthritis. BME in absence of intra-articular signal changes had a lower SN and LR+ for spondyloarthritis (SN = 20.5%, LR+ 1.4). Concomitant BME and high T1 signal (SP = 97.2%, LR + = 10.5), BME and fluid signal (SP = 98.6%, LR + = 10.3) or BME and ankylosis (SP = 100%) had higher SP and LR+ for spondyloarthritis. Concomitant BME and VP had low LR+ for spondyloarthritis (SP = 91%, LR + =0.9). When BME was absent, intra-articular signal changes were less prevalent, but remained highly specific for spondyloarthritis. CONCLUSION: Our results suggest that both periarticular and intra-articular MR signal of the sacroiliac joint should be examined to determine whether an MRI is 'positive' or 'not positive' for sacroiliitis associated with spondyloarthritis.

MR signal in the sacroiliac joint space in spondyloarthritis: a new sign.

OBJECTIVES: To determine the diagnostic value of MR signal within the sacroiliac (SI) joint space in spondyloarthritis (SpA). METHODS: A retrospective analysis of MRIs of SI joints was performed in 363 patients, aged 16-45 years, clinically suspected of sacroiliitis. Intra-articular SI joint MR signals were categorized as normal, high T1 signal, fluid signal, ankylosis or vacuum phenomenon (VP). These MRI findings were correlated with the final diagnosis, according to the ASAS criteria. Sensitivity, specificity, and positive and negative likelihood ratios (LR) and predictive values were calculated. RESULTS: Presence of intra-articular high T1 signal, fluid signal and ankylosis had a specificity of 95.8 %, 95.3 % and 99.5 % for SpA. High T1 signal, fluid signal and ankylosis were present in 38.4 %, 19.2 % and 17.9 % of SpA patients and in 4.2 %, 4.7 % and 0.5 % of patients without SpA, resulting in LR+ of 9.0, 4.1 and 37.9, respectively. VP was present in 13.2 % of SpA patients and in 20.8 % of patients without SpA, resulting in an LR+ of 0.6. CONCLUSIONS: Presence of high T1 signal, fluid signal and ankylosis within the SI joint on MRI have high specificity for SpA. High T1 signal is the most sensitive MRI feature within the SI joint for SpA. KEY POINTS: • MRI of the SI joints is typically obtained for diagnosis of spondyloarthritis. • The MR signal within the SI joint itself reflects features of spondyloarthritis. • Intra-articular high T1 signal, fluid signal and ankylosis are seen in spondyloarthritis. • The vacuum phenomenon makes spondyloarthritis less likely.

Diagnostic value of MRI features of sacroiliitis in juvenile spondyloarthritis.

AIM: To determine the diagnostic utility of magnetic resonance imaging (MRI) features of sacroiliitis in juvenile spondyloarthritis (JSpA). MATERIALS AND METHODS: This was a prospective study of 80 paediatric patients who underwent MRI of the sacroiliac joints that were clinically suspected to have sacroiliitis. The prevalence of MRI features of active and structural lesions of sacroiliitis was recorded. Patients were classified according to the International League of Association for Rheumatology criteria. The MRI findings were compared to the final clinical diagnosis. RESULTS: Sacroiliitis was seen in 25/80 (31%) patients. MRI showed active inflammation in 23 patients (29%): synovial enhancement (28%), high short tau inversion recovery (STIR)-signal in the joint space (29%), bone marrow oedema (BMO; 20%), and capsulitis (8%). Structural changes were present in 14 patients (18%): erosion (14%), fat infiltration (13%), sclerosis (8%), and ankylosis (1%). Of all MRI features, ankylosis (100%), capsulitis (98%), BMO (96%), and erosion (96%) had the highest specificity for JSpA; global diagnostic impression (55%) and synovial enhancement (52%) were the MRI features with the highest sensitivity. The likelihood ratios (LR+) for diagnosis of JSpA were high for BMO (10.5), capsulitis (7.5), global diagnostic impression (6.9), and erosions (6.75), but greater for BMO concomitant with synovial enhancement (LR+ 19.5) and for erosion concomitant with BMO (LR+ 12) or synovial enhancement (LR+ 13.5). CONCLUSION: There are multiple features of active inflammation and structural damage visible at MRI of the sacroiliac joints that can provide a specific diagnosis of JSpA when present in children with suspected sacroiliitis. Synovial enhancement is the MRI feature with the highest sensitivity for JSpA. If BMO is seen concomitant with synovial enhancement or erosion, the diagnosis of JSpA is very likely. Ankylosis, capsulitis, bone marrow oedema, and erosion all have a high specificity for JSpA. Absence of MRI findings of sacroiliitis does not exclude the diagnosis of JSpA.

Limited role of gadolinium to detect active sacroiliitis on MRI in juvenile spondyloarthritis.

OBJECTIVE: The aim of this study is to determine the added diagnostic value of contrast-enhanced (CE) magnetic resonance imaging (MRI) compared to routine non contrast-enhanced MRI to detect active sacroiliitis in clinically juvenile spondyloarthritis (JSpA). MATERIALS AND METHODS: A total of 80 children clinically suspected for sacroiliitis prospectively underwent MRI of the sacroiliac (SI) joints. Axial and coronal T1-weighted (T1), Short-tau inversion recovery (STIR) and fat-saturated T1-weighted gadolinium-DTPA (Gd) contrast-enhanced (T1/Gd) sequences were obtained. The presence of bone marrow edema (BME), capsulitis, enthesitis, high intra-articular STIR signal, synovial enhancement and a global diagnostic impression of the MRI for diagnosis of sacroiliitis was recorded. RESULTS: STIR and T1/Gd sequences had 100% agreement for depiction of BME, capsulitis and enthesitis. High intra-articular STIR signal was seen in 18/80 (22.5%) patients, 15 (83%) of whom also showed synovial enhancement in the T1/Gd sequence. Sensitivity (SN) and specificity (SP) for a clinical diagnosis of JSpA were similar for high STIR signal (SN = 33%, SP = 85%) and T1/Gd synovial enhancement (SN = 36%, SP = 92%). Positive likelihood ratio (LR+) for JSpA was twice as high for synovial enhancement than high STIR signal (4.5 compared to 2.2). Global diagnostic impression was similar (STIR: SN = 55%, SP = 87%, LR + =4 .2; T1/Gd: SN = 55%, SP = 92%, LR + = 6.9). CONCLUSION: MRI without contrast administration is sufficient to identify bone marrow edema, capsulitis and retroarticular enthesitis as features of active sacroiliitis in juvenile spondyloarthritis. In selected cases when high STIR signal in the joint is the only finding, gadolinium-enhanced images may help to confirm the presence of synovitis.

Direct comparison of conventional radiography and cone-beam CT in small bone and joint trauma.

OBJECTIVE: To compare the diagnostic value of cone-beam computed tomography (CBCT) and conventional radiography (CR) after acute small bone or joint trauma. MATERIALS AND METHODS: Between March 2013 and January 2014, 231 patients with recent small bone or joint trauma underwent CR and subsequent CBCT. CR and CBCT examinations were independently assessed by two readers, blinded to the result of the other modality. The total number of fractures as well as the number of complex fractures were compared, and inter- and intraobserver agreement for CBCT was calculated. In addition, radiation doses and evaluation times for both modalities were noted and statistically compared. RESULTS: Fracture detection on CBCT increased by 35% and 37% for reader 1 and reader 2, respectively, and identification of complex fractures increased by 236% and 185%. Interobserver agreement for CBCT was almost perfect, as was intraobserver agreement for reader 1. The intraobserver agreement for reader 2 was substantial. Radiation doses and evaluation time were significantly higher for CBCT. CONCLUSION: CBCT detects significantly more small bone and joint fractures, in particular complex fractures, than CR. In the majority of cases, the clinical implication of the additionally detected fractures is limited, but in some patients (e.g., fracture-dislocations), the management is significantly influenced by these findings. As the radiation dose for CBCT substantially exceeds that of CR, we suggest adhering to CR as the first-line examination after small bone and joint trauma and keeping CBCT for patients with clinical-radiographic discordance or suspected complex fractures in need of further (preoperative) assessment.

Diagnostic value of pelvic enthesitis on MRI of the sacroiliac joints in spondyloarthritis.

OBJECTIVE: To determine the prevalence and diagnostic value of pelvic enthesitis on MRI of the sacroiliac (SI) joints in spondyloarthritis (SpA). MATERIALS AND METHODS: A retrospective study in 444 patients aged 17-45 years old with MRI of the SI joints and with clinically suspected sacroiliitis was performed. Patients were classified as having SpA if they fulfilled the Assessment of Spondyloarthritis International Society (ASAS) criteria. Pelvic enthesitis on MRI was correlated with the final diagnosis. Sensitivity, specificity, positive and negative likelihood ratio (LR) and predictive values (PV) of pelvic enthesitis for the diagnosis of SpA were calculated. RESULTS: MRI showed pelvic enthesitis in 24.4 % of patients with SpA and in 7.1 % of patients without SpA. Presence of any enthesitis had sensitivity, specificity, LR+, LR-, PPV and NPV of 24.4 %, 92.9 %, 3.45, 0.81, 69.4 % and 65.2 % for the diagnosis of SpA, respectively. The most commonly affected entheses were the longitudinal ligament insertion (4.5 %), the retroarticular ligaments (4.1 %) and the pubic symphysis (4.1 %). The sites of enthesitis with the highest PPV for SpA were the iliac crest/wing (85.7 %) and the retroarticular ligaments (81.3 %). CONCLUSION: Nearly one fourth of SpA patients with suspected sacroiliitis showed pelvic enthesitis on MRI. Such pelvic enthesitis has a high specificity for the diagnosis of spondyloarthritis. KEY POINTS: • Enthesitis is the primary clinical feature of spondyloarthritis. • Magnetic resonance imaging of the sacroiliac joints can demonstrate pelvic enthesitis. • Pelvic enthesitis has a high specificity for the diagnosis of spondyloarthritis.

Dynamic contrast-enhanced MR imaging for differentiation between enchondroma and chondrosarcoma.

OBJECTIVES: To determine whether dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) can differentiate benign from malignant cartilage tumours compared to standard MRI. To investigate whether a cutoff value could be determined to differentiate enchondroma from low-grade chondrosarcoma (CS) more accurately. METHODS: One hundred six patients were included in this retrospective study: 75 with enchondromas (mean age = 41 years) and 31 with CS (mean age = 47 years). Within this population, a subgroup of patients was selected with the tumour arising in a long bone. At the time of diagnosis, the tumours were evaluated on MRI, including standard MRI, DCE-MRI, and region-of-interest (ROI) analysis to obtain information on tumour vascularisation and perfusion. RESULTS: The main cutoff value to differentiate enchondroma from CS contained a two-fold more relative enhancement compared with muscle, combined with a 4.5 (= 76°) slope value, with 100 % sensitivity and 63.3 % specificity. The prediction of CS diagnosis with DCE-MRI had 93.4 % accuracy. The accuracy of the standard MRI parameters was equal to the DCE-MRI parameters. CONCLUSIONS: Standard MRI and DCE-MRI both play an important and complementary role in differentiating enchondroma from low-grade CS. A combination of both imaging techniques leads to the highest diagnostic accuracy for differentiating cartilaginous tumours. KEY POINTS: • DCE-MRI plays an important role in differentiating benign from malignant cartilage tumours. • Retrospective study defined a threshold for 100 % detection of chondrosarcoma with DCE-MRI. • The threshold values were relative enhancement = 2 and slope = 4.5. • One hundred per cent chondrosarcoma detection corresponds with 36.7 % false-positive diagnosis of enchondroma. • Standard MRI is complementary to DCE-MRI in differentiating cartilaginous tumours.

Magnetic resonance imaging of the sternal extremity of the clavicle in forensic age estimation: towards more sound age estimates.

OBJECTIVES: The development of the sternal extremity of the clavicle was examined prospectively with magnetic resonance imaging (MRI) for forensic bone age assessment. The objectives were to examine whether these results were comparable with the literature on plain radiography and CT, to provide age prediction intervals that correctly reflect the high variability in clavicular growth among individuals and to investigate whether MRI of the clavicle can be used to differentiate between individuals younger or older than 18 years. METHODS: The clavicles of 220 volunteers (16-26 years) were examined with 3-T MRI and evaluated according to the Schmeling and Kreitner classification (Schmeling, Int J Legal Med 118:5-8, 2004; Kreitner, Eur Radiol 8:1116-1122, 1998). An additional hand/wrist radiograph was taken and evaluated according to Greulich and Pyle (1959). After a descriptive analysis, a multivariate ordinal regression model was fitted and embedded in a Bayesian framework based on Thevissen et al. (Int J Legal Med 124:35-42, 2009). RESULTS: The descriptive results were concordant with the literature, although the Kreitner classification is recommended and simultaneous evaluation of the hand is considered a basic requirement (Schmeling, Int J Legal Med 118:5-8, 2004). The 95 % credibility interval for both genders with bilateral stage IV is 20-26 years. The corresponding estimated probability of being younger than 18 years is 0.8 % in females and 0.2 % in males. CONCLUSION: MRI of the sternal extremity of the clavicle can be used to differentiate between being younger or older than 18, but a simultaneous evaluation of the hand/wrist is essential. Future evaluation of the predictive performance of the model, using comparable but larger reference samples, is necessary to validate these results.

Genetic characteristics of Shiga toxin-producing E. coli O157, O26, O103, O111 and O145 isolates from humans, food, and cattle in Belgium.

In this study, we characterized 272 Shiga toxin-producing Escherichia coli (STEC) isolates from humans, food, and cattle in Belgium [O157 (n = 205), O26 (n = 31), O103 (n = 15), O111 (n = 10), O145 (n = 11)] for their virulence profile, whole genome variations and relationships on different genetic levels. Isolates of O157 displayed a wide variation of stx genotypes, heterogeneously distributed among pulsogroups (80% similarity), but with a concordance at the pulsosubgroup level (90% similarity). Of all serogroups evaluated, the presence of eae was conserved, whereas genes encoded on the large plasmid (ehx, espP, katP) occurred in variable combinations in O26, O103, and O145. The odds of having haemolytic uraemic syndrome was less for all genotypes stx2a, stx2c, stx1/stx2c, and stx1 compared to genotype stx2a/stx2c; and for patients aged >5 years compared to patients aged ≤ 5 years. Based on the genetic typing and by using epidemiological data, we could confirm outbreak isolates and suggest epidemiological relationships between some sporadic cases. Undistinguishable pulsotypes or clones with minor genotypic variations were found in humans, food, and cattle in different years, which demonstrated the important role of cattle as a reservoir of STEC O157, and the circulation and persistence of pathogenic clones.

3 T DCE-MRI assessment of synovitis of the interphalangeal joints in patients with erosive osteoarthritis for treatment response monitoring.

OBJECTIVE: To study the value of 3 T dynamic contrast-enhanced (DCE)-MRI for assessment of synovitis of the interphalangeal joints in patients with erosive osteoarthritis (EOA) for treatment response monitoring. MATERIALS AND METHODS: The interphalangeal joints of fingers two to five were examined at 3 T MRI in nine patients with EOA. Two musculoskeletal radiologists recorded erosions, bone marrow oedema (BME), synovitis and osteophytes. Interobserver reliability was calculated using κ statistics. In six patients, DCE-MRI time intensity curves of synovitis in two affected joints were analysed. The maximum upslope, absolute and relative enhancement of synovitis were compared with MRI after 12 months of anti-tumour necrosis factor treatment. Intraobserver reproducibility was calculated using intra-class correlation coefficient. RESULTS: Interobserver reliability was 'good' for detection of erosions (κ = 0.70), BME (κ = 0.77) and synovitis (κ = 0.77), but 'poor' for osteophytes (κ = 0.12). Post-treatment DCE-MRI showed decreasing maximum upslope (p = 0.002) and absolute (p = 0.002) and relative (p = 0.01) enhancement compared to the initial scan. Intraobserver reproducibility of DCE-MRI was 'almost perfect' or 'strong' for all parameters. CONCLUSIONS: 3 T DCE-MRI demonstrates changes in time intensity curves of synovitis in EOA of the interphalangeal joints in a longitudinal study, indicating this technique is promising for monitoring therapy response.

Evaluation of a multiplex-PCR detection in combination with an isolation method for STEC O26, O103, O111, O145 and sorbitol fermenting O157 in food.

The aim of the current study was to evaluate a multiplex PCR (mPCR) detection test combined with the evaluation of a previously described isolation method. Minced beef, raw-milk cheese and sprouted seed samples were inoculated with low amounts (7-58 cfu 25 g(-1)) of non-stressed, cold-stressed or freeze-stressed clinical STEC strains, including serogroups O26, O103, O111, O145, sorbitol fermenting (SF) O157 and non-sorbitol fermenting (NSF) O157. The inoculated pathogen was detected using a 24 h-enrichment followed by an mPCR protocol, and in parallel isolated using an enrichment step of 6 and 24 h, followed by selective plating of the enriched broth and selective plating of the immunomagnetic separation (IMS) product. Recovery results were evaluated and compared. Successful mPCR detection and isolation was obtained for non-stressed and cold-stressed STEC cells in minced beef and raw-milk cheese samples, except for serogroups O111 and SF O157. For freeze-stressed cells and sprouted seed samples, false negatives were often found. Isolation was better after 24 h-enrichment compared to 6 h-enrichment. IMS improved in some cases the isolation of non-stressed and cold-stressed cells belonging to serogroups O111 and O157 from minced beef and raw-milk cheese and freeze-stressed cells of all tested serogroups from minced beef.

Effects of in vivo exercise on ankle cartilage deformation and recovery in healthy volunteers: an experimental study.

OBJECTIVE: To monitor ankle cartilage 3D volume changes after in vivo exercise and during recovery. METHOD: Based on 3D MRI, 3D volumes of talar and tibial cartilage were calculated before and after 30 bilateral knee bends in 12 healthy volunteers. 3D volumes were calculated at five time points (one pre- and four post-scans) determining deformation and recovery for both cartilage plates of interest. Post-scans ran immediately after the exercise and were repeated according to a 15 min interval. 3D volumes were subjected to repeated measures GLM. Additionally, relative surface area use during deformation was compared between plates using a Wilcoxon Signed Ranks test and its correlation with deformation was investigated using Spearman's rho. RESULTS: Mean 3D volume change percentages for talar cartilage after the exercise were: -10.41%, -8.18%, -5.61% and -3.90%. For tibial cartilage mean changes were: -5.97%, -5.75%, +0.89% and +1.51%. For talar cartilage changes were significant, except following 30 min post-exercise. For tibial cartilage no changes were significant. At all time points, no significant differences in relative volume changes between both cartilage plates existed. Although no significant differences in relative surface area use between plates were revealed, a moderate to strong correlation with deformation existed. CONCLUSION: Ankle cartilage endures substantial deformation after in vivo loading that was restored within 30 min for the talus. Overall cartilage contact area involvement might be associated with cartilage quality maintenance in the upper ankle. Talar cartilage is suggested to play a critical role in intra-articular shock attenuation when compared to tibial cartilage.

Magnetic resonance imaging of the medial extremity of the clavicle in forensic bone age determination: a new four-minute approach.

OBJECTIVES: The use of 3T magnetic resonance imaging (MRI) of the clavicle in forensic bone age determination was prospectively examined and compared with plain radiography. METHODS: Four MRI sequences and three radiographs of 121 healthy subjects between 11 and 30 were studied by two observers. RESULTS: The number of images assessable for bone age determination was lower for plain radiography (PA: 68.7%; oblique: 97.5%) compared with MRI (VIBE: 99.0%). Concerning the subjective level of difficulty to assess bone age, the observers found it easier to assess bone age on MRI than on radiography. The developmental stages of the clavicle, as used on plain radiography, were transferable to MRI. Especially the VIBE gradient echo sequence provided an excellent depiction of the growth cartilage and ossification centre with a slice thickness of 0.9 mm and only a 4-min acquisition time. When the developmental stages were assigned, less variability between the observers was seen on MRI, compared with plain radiography. CONCLUSION: We conclude that 3T MRI provides high resolution, cross-sectional images of the maturation of the clavicle without ionising radiation in a very short time, allowing more accurate determination of bone age than plain radiography.

MRI demonstrates the extension of juxta-articular venous malformation of the knee and correlates with joint changes.

OBJECTIVE: Juxta-articular venous malformations (VMs) are uncommon, but may cause early arthropathy of the knee in children and adolescents. We sought to describe the prevalence, extent and initial magnetic resonance imaging (MRI) features of knee arthropathy in children with VM adjacent to the knee joint. METHODS: Thirty-five patients with VM adjacent to the knee who had MRI performed between 2000 and 2009 were identified through a keyword search of the radiology information system. RESULTS: VM extended to the joint in 17 of the 35 patients (5.4-21.5 years, mean 11.8 years). Most of these 17 patients had joint changes (15/17, 88%), most commonly haemosiderin deposition (14/17, 82%). Other findings included the presence of subchondral bone lesions (eight, 47%), cartilage loss (six, 35%), synovial thickening (six, 35%), marrow oedema (six, 35%), joint effusion (five, 29%), subchondral cysts (five, 29%) and one loose body (6%). VM location and size did not correlate with the degree of articular involvement. Joint changes were present in focal as well as non-discrete VM. CONCLUSION: We found that the frequency of arthropathy increased with extension of VM into the joint itself. This finding stresses the importance of early MRI evaluation of all juxta-articular VM.

Health technology assessment of magnetic resonance.

MR imaging has established itself as a reliable means of imaging pathology in many different regions of the body without the disadvantage of ionizing radiation. There was also hope that MRI might replace not only CT but also more invasive imaging techniques. Until now the substitution, especially that of CT has been less than expected. To evaluate the possible substitution of CT by MR imaging, it is paramount to have high quality evidence regarding the efficacy of MRI. This was collected by performing a systematic search of the available literature using Medical Subject Heading (MeSH) terms. The retrieved articles were classified according to the different levels of diagnostic efficacy as described by Fryback and Thornbury. Based on the available studies and the quality assessment, a level of evidence is attributed for the diagnostic efficacy of MRI in each indication.

Health technology assessment of magnetic resonance imaging of the knee.

A search of the available literature was performed and the role of MR imaging of the knee is discussed. Based on this search the authors concluded that MR has a high sensitivity in detecting any abnormalities in the knee but it does not have the same diagnostic accuracy as a clinical investigation performed by a trained knee specialist when all knee injuries are taken together. It does lead to a decrease in the number of surgical interventions due to its high negative predictive value. For the detection of meniscal injury, MR has the same accuracy as arthroscopy and should be performed in order to avoid unnecessary surgical interventions. A negative MR also obviates further investigation in suspected cartilage damage. This is not true for anterior and posterior cruciate ligament problems where MRI is less accurate than clinical investigation.

Health technology assessment of magnetic resonance imaging of the spine and bone marrow.

The high spatial resolution and the lack of ionizing radiation, makes magnetic resonance imaging the method of choice for imaging most spinal pathology, especially if associated with neurological symptoms. However, due to the high sensitivity of MR imaging, careful correlation between imaging findings and clinical findings is important to ensure appropriate treatment. Substituting radiographic evaluations for rapid MRI in the primary care setting may offer little additional benefit to patients. It may even increase the costs of care but the decisions about the use of imaging depend on judgments concerning whether the small observed improvement in outcome justifies additional cost. Because the presence of an abscess is a major factor in deciding between conservative and surgical treatment, MRI plays an essential role in the decision-making process concerning the treatment of spondylodiscitis. MR is also the method of choice for quantitative evaluation of bone marrow in lymphoma patients when a crucial therapeutic decision has to be made or for the qualitative evaluation of the spinal cord if compression is suspected in primary spinal malignancy or metastatic disease.

Imaging of the opacified middle ear.

Middle ear opacification on imaging studies performed in a non-traumatic setting mostly reflects chronic inflammatory/infectious disease. In some of these patients an underlying cholesteatoma will be found. High-resolution computed tomography examinations and magnetic resonance imaging are often used in the work-out of the disease. High-resolution computed tomography of the opacified middle ear serves to describe the status of the ossicular chain, and its suspensory apparatus, as well as the status of the tympanic and mastoid wall. When ossicular erosions are visualized, the probability of a present cholesteatoma is about 90%. Whereas high-resolution computed tomography is not able to differentiate cholesteatoma from other types of opacification, magnetic resonance imaging is. The combined use of delayed post-Gd T1-weighted images and non-EPI based DWI seems to be the actual best option on this matter.

Arachnoid granulations of the posterior temporal bone wall: imaging appearance and differential diagnosis.

Arachnoid granulations are rarely seen on high-resolution CT (HRCT) at the posterior temporal bone wall, where they appear as erosions, without bone spicules and often with a lobulated surface. Differential diagnosis includes endolymphatic sac tumor, paraganglioma, chordoma, and chondromatous and metastatic tumors. MR imaging can confirm the diagnosis because arachnoid granulations behave like CSF without gadolinium enhancement. This report aims to illustrate the appearance and differentiation of temporal bone arachnoid granulations on HRCT and MR imaging.

Forensic age estimation based on development of third molars: a staging technique for magnetic resonance imaging.

BACKGROUND: The development of third molars can be evaluated with medical imaging to estimate age in subadults. The appearance of third molars on magnetic resonance imaging (MRI) differs greatly from that on radiographs. Therefore a specific staging technique is necessary to classify third molar development on MRI and to apply it for age estimation. AIM: To develop a specific staging technique to register third molar development on MRI and to evaluate its performance for age estimation in subadults. MATERIALS AND METHODS: Using 3T MRI in three planes, all third molars were evaluated in 309 healthy Caucasian participants from 14 to 26 years old. According to the appearance of the developing third molars on MRI, descriptive criteria and schematic representations were established to define a specific staging technique. Two observers, with different levels of experience, staged all third molars independently with the developed technique. Intra- and inter-observer agreement were calculated. The data were imported in a Bayesian model for age estimation as described by Fieuws et al. (2016). This approach adequately handles correlation between age indicators and missing age indicators. It was used to calculate a point estimate and a prediction interval of the estimated age. Observed age minus predicted age was calculated, reflecting the error of the estimate. RESULTS: One-hundred and sixty-six third molars were agenetic. Five percent (51/1096) of upper third molars and 7% (70/1044) of lower third molars were not assessable. Kappa for inter-observer agreement ranged from 0.76 to 0.80. For intra-observer agreement kappa ranged from 0.80 to 0.89. However, two stage differences between observers or between staging sessions occurred in up to 2.2% (20/899) of assessments, probably due to a learning effect. Using the Bayesian model for age estimation, a mean absolute error of 2.0 years in females and 1.7 years in males was obtained. Root mean squared error equalled 2.38 years and 2.06 years respectively. The performance to discern minors from adults was better for males than for females, with specificities of 96% and 73% respectively. CONCLUSION: Age estimations based on the proposed staging method for third molars on MRI showed comparable reproducibility and performance as the established methods based on radiographs.