Diffusion Tensor Imaging for Diagnosing Root Avulsions in Traumatic Adult Brachial Plexus Injuries: A Proof-of-Concept Study.

Cross-sectional MRI has modest diagnostic accuracy for diagnosing traumatic brachial plexus root avulsions. Consequently, patients either undergo major exploratory surgery or months of surveillance to determine if and what nerve reconstruction is needed. This study aimed to develop a diffusion tensor imaging (DTI) protocol at 3 Tesla to visualize normal roots and identify traumatic root avulsions of the brachial plexus. Seven healthy adults and 12 adults with known (operatively explored) unilateral traumatic brachial plexus root avulsions were scanned. DTI was acquired using a single-shot echo-planar imaging sequence at 3 Tesla. The brachial plexus was visualized by deterministic tractography. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated for injured and avulsed roots in the lateral recesses of the vertebral foramen. Compared to healthy nerves roots, the FA of avulsed nerve roots was lower (mean difference 0.1 [95% CI 0.07, 0.13]; p < 0.001) and the MD was greater (mean difference 0.32 × 10-3 mm2/s [95% CI 0.11, 0.53]; p < 0.001). Deterministic tractography reconstructed both normal roots and root avulsions of the brachial plexus; the negative-predictive value for at least one root avulsion was 100% (95% CI 78, 100). Therefore, DTI might help visualize both normal and injured roots of the brachial plexus aided by tractography. The precision of this technique and how it relates to neural microstructure will be further investigated in a prospective diagnostic accuracy study of patients with acute brachial plexus injuries.

Normal values and test-retest variability of stimulated-echo diffusion tensor imaging and fat fraction measurements in the muscle.

OBJECTIVES: To assess the test-retest variability of both diffusion parameters and fat fraction (FF) estimates in normal muscle, and to assess differences in normal values between muscles in the thigh. METHODS: 29 healthy volunteers (mean age 37 years, range 20-60 years, 17/29 males) completed the study. Magnetic resonance images of the mid-thigh were acquired using a stimulated echo acquisition mode-echoplanar imaging (STEAM-EPI) imaging sequence, to assess diffusion, and 2-point Dixon imaging, to assess FF. Imaging was repeated in 19 participants after a 30 min interval in order to assess test-retest variability of the measurements. RESULTS: Intraclass correlation coefficients (ICCs) for test-retest variability were 0.99 [95% confidence interval, (CI): 0.98, 1] for FF, 0.94 (95% CI: 0.84, 0.97) for mean diffusivity and 0.89 (95% CI: 0.74, 0.96) for fractional anisotropy (FA). FF was higher in the hamstrings than the quadriceps by a mean difference of 1.81% (95% CI:1.63, 2.00)%, p < 0.001. Mean diffusivity was significantly lower in the hamstrings than the quadriceps (0.26 (0.13, 0.39) x10-3 mm2s-1, p < 0.001) whereas fractional anisotropy was significantly higher in the hamstrings relative to the quadriceps with a mean difference of 0.063 (0.05, 0.07), p < 0.001. CONCLUSIONS: This study has shown excellent test-retest, variability in MR-based FF and diffusion measurements and demonstrated significant differences in these measures between hamstrings and quadriceps in the healthy thigh. ADVANCES IN KNOWLEDGE: Test-retest variability is excellent for STEAM-EPI diffusion and 2-point Dixon-based FF measurements in the healthy muscle. Inter- and intraobserver variability were excellent for region of interest placement for STEAM-EPI diffusion and 2-point Dixon-based FF measurements in the healthy muscle. There are significant differences in FF and diffusion measurements between the hamstrings and quadriceps in the normal muscle.

An In Vitro Study of the Intervertebral Disc Structure Using 3 T Magnetic Resonance Imaging.

STUDY DESIGN: An in vitro magnetic resonance imaging (MRI) study. OBJECTIVE: Investigate the potential of high-field MRI for producing higher quality images of the intervertebral disc (IVD) to better distinguish structural details. SUMMARY OF BACKGROUND DATA: Higher spatial and contrast resolution are important advantages when imaging the complex tissue structures in the spine such as the IVDs. However, at present it is challenging to capture the substructural details in the IVD such as the lamellae. METHODS: Three MRI sequences; two-dimensional proton-density-weighted Turbo-Spin-Echo (PD-TSE), 2D T2-weighted Turbo-Spin-Echo (T2W-TSE) with fat-saturation (FS), and 3D Spoiled-Gradient-Echo (3D-GE), were modified based on the image quality and scan duration. IVDs of three intact cadaveric lumbar-spines (T12-S1, Age 83-94 yr) were imaged using these optimized sequences. Thereafter each IVD was transversely sectioned and the exposed surfaces were photographed. Landmark observations from corresponding MRI slices and photographs were compared to confirm the MRI captured morphology. The image quality was evaluated using signal-to-noise ratio (SNR), and relative-contrast values. Finally, the underlying tissue structures, including specific pathological features, were qualitatively compared between the MR images and photographs. RESULTS: Observations from photographs and corresponding MRI slices matched well. The PD-TSE sequence had better overall SNR, but the relative contrast between the tissue types was relatively poor. The 3D-GE sequence had higher relative contrast between the IVD and bone, but not between annulus and nucleus regions. The T2W images provided the best relative contrast between the annulus and nucleus, however the standard deviations here were high. Structural details including fissures, vascular and granular tissue proliferation, and pathologies in the endplate region, were identifiable from the MR images obtained using the optimized sequences. CONCLUSION: The results demonstrate the potential of high-field MRI to capture the IVD structural details. Since the acquisition durations were within clinically acceptable levels, these methodological improvements have the potential to enhance clinical diagnostics. LEVEL OF EVIDENCE: 4.

High-resolution MRI assessment of dactylitis in psoriatic arthritis shows flexor tendon pulley and sheath-related enthesitis.

OBJECTIVE: Dactylitis is a hallmark of psoriatic arthritis (PsA) where flexor tenosynovitis is common. This study explored the microanatomical basis of dactylitis using high-resolution MRI (hrMRI) to visualise the small entheses around the digits. METHODS: Twelve patients with psoriatic dactylitis (4 fingers, 8 toes), and 10 healthy volunteers (6 fingers, 4 toes) had hrMRI of the digits using a 'microscopy' coil and contrast enhancement. All structures were evaluated including the tendons and ligaments, related enthesis organs, pulleys, volar/plantar plates and tendon sheaths. RESULTS: In dactylitis, collateral ligament enthesitis was seen in nine digits (75%), extensor tendon enthesitis in six digits (50%), functional enthesitis (5 digits, 42%), abnormal enhancement at the volar plates (2/5 joints, 40%) and the plantar plate (1/5 joints, 20%). Nine cases (75%) demonstrated flexor tenosynovitis, with flexor tendon pulley/flexor sheath microenthesopathy observed in 50% of all cases. Less abnormalities which were milder was observed in the normal controls, none of whom had any signal changes in the tendon pulleys or fibrous sheaths. CONCLUSIONS: This study provides proof of concept for a link between dactylitis and 'digital polyenthesitis' including disease of the miniature enthesis pulleys of the flexor tendons, further affirming the concept of enthesitis in PsA.

Gadofosveset-based biomarker of tissue albumin concentration: Technical validation in vitro and feasibility in vivo.

PURPOSE: There is currently no adequate method of mapping physiologic and pathophysiologic tissue albumin concentrations in human subjects. The objective of this study was to devise and evaluate a biomarker of regional albumin concentration using gadofosveset-enhanced MRI. THEORY AND METHODS: A binding and relaxation model was devised and evaluated in vitro in solutions of albumin at 3.0 Tesla (T) and 4.7T. The method was evaluated in the heart in seven volunteers at 3.0T. RESULTS: MRI-derived estimates of albumin concentration were in good agreement with true values over the range 0.1-1.0 mM (Pearson correlation coefficients of 0.85 and 0.88 for 3.0T and 4.7T, respectively). The mean calculated albumin concentration in the myocardium for the volunteers was 0.02 mM (range, 0.01-0.03 mM). CONCLUSION: Accurate estimates of albumin concentration in vitro suggest this may be a viable noninvasive alternative to existing techniques. In the myocardium the MRI-derived estimates of albumin concentration indicate the practical feasibility of the technique but were below expected values. Gadofosveset-enhanced MR relaxometry has potential in providing biomarkers of regional albumin concentration; further evaluation is required before it can be used reliably in vivo.

The microanatomic basis of finger clubbing - a high-resolution magnetic resonance imaging study.

OBJECTIVE: Hypervascularization in finger clubbing is recognized, but its microanatomical basis remains unclear. This pilot descriptive study used magnetic resonance imaging (MRI) to explore this further. METHODS: High-resolution MRI acquired with contrast agent was carried out in 4 patients with finger clubbing and 4 healthy volunteers. The anatomy of the nail bed, capsular structures, and bony changes were described. RESULTS: Marked nail bed thickening and contrast enhancement was noted in all clubbed fingers, with bone edema in 3 of the 4 patients. None of the healthy subjects had similar abnormalities. CONCLUSION: This confirms that hypervascularization of the nail bed observed in the microanatomy on high-resolution MRI is associated with clubbed appearances of the nails.

High-resolution [18F]fluoride positron emission tomography of the distal interphalangeal joint in psoriatic arthritis--a bone-enthesis-nail complex.

OBJECTIVE: This study used high-resolution PET to explore the pattern of DIP joint bone metabolism to test the hypothesis that the nail was functionally integrated with the bone, based on patterns of distal phalange (DP) bone metabolism in PsA compared with OA and normal joints. METHODS: A total of 234 DIP joints were scanned in 30 subjects (10 PsA, 10 OA, 10 healthy control) with [18F]fluoride using the quad-high-density avalanche chamber nano PET scanner. The images were assessed blinded to diagnosis and symptoms for site and intensity of increased [18F]fluoride uptake. RESULTS: [18F]fluoride uptake in the DP was strong relative to the intermediate phalange in both PsA and OA. In PsA there was a trend for uptake to occur in a diffuse pattern involving the entire DP. There was also greater uptake at the enthesis, the periosteum and at the tufts of the DP of PsA compared with OA. In OA, uptake was greatest in the subchondral region adjacent to known sites of osteophytosis and erosions. Both PsA and OA joints with uptake at the subchondral or periosteal bone are likely to be more symptomatic. CONCLUSION: This exploratory study suggested diffuse increased bone metabolism involving the entire DP, periosteum and entheses, especially in PsA. The subchondral bone and periosteum at the DP have large concentrations of enthesis attachments, including attachments from the nail, supporting the concept of an integrated nail and joint apparatus leading to a wide area of abnormal bone metabolism in PsA.

Visualization and quantification of whole rat heart laminar structure using high-spatial resolution contrast-enhanced MRI.

It has been shown by histology that cardiac myocytes are organized into laminae and this structure is important in function, both influencing the spread of electrical activation and enabling myocardial thickening in systole by laminar sliding. We have carried out high-spatial resolution three-dimensional MRI of the ventricular myolaminae of the entire volume of the isolated rat heart after contrast perfusion [dimeglumine gadopentate (Gd-DTPA)]. Four ex vivo rat hearts were perfused with Gd-DTPA and fixative and high-spatial resolution MRI was performed on a 9.4T MRI system. After MRI, cryosectioning followed by histology was performed. Images from MRI and histology were aligned, described, and quantitatively compared. In the three-dimensional MR images we directly show the presence of laminae and demonstrate that these are highly branching and are absent from much of the subepicardium. We visualized these MRI volumes to demonstrate laminar architecture and quantitatively demonstrated that the structural features observed are similar to those imaged in histology. We showed qualitatively and quantitatively that laminar architecture is similar in the four hearts. MRI can be used to image the laminar architecture of ex vivo hearts in three dimensions, and the images produced are qualitatively and quantitatively comparable with histology. We have demonstrated in the rat that: 1) laminar architecture is consistent between hearts; 2) myolaminae are absent from much of the subepicardium; and 3) although localized orthotropy is present throughout the myocardium, tracked myolaminae are branching structures and do not have a discrete identity.

Influence of cellulose on ion diffusivity in 1-ethyl-3-methyl-imidazolium acetate cellulose solutions.

Solutions of microcrystalline cellulose in 1-ethyl-3-methyl-imidazolium acetate have been investigated using pulsed-field gradient (1)H NMR. In all cases the geometrically larger cation was found to diffuse faster than the smaller anion. Arrhenius temperature analysis has been applied to the ion diffusivities giving activation energies. The diffusion and published viscosity data for these solutions were shown to follow the Stokes-Einstein relationship, giving hydrodynamic radii of 1.6 Š(cation) and 1.8 Š(anion). Theories for obstruction, free-volume and hydrodynamic effects on solvent diffusion have been applied. The Mackie-Meares and Maxwell-Fricke obstruction models provided a correct trend only when assuming a certain fraction of ions are bound to the polymer. From this fraction it was shown that the maximum dissolvable cellulose concentration is ∼27% w/w, which is consistent with the highest known prepared concentration of cellulose in this ionic liquid. The Phillies' hydrodynamic model is found to give the best description for the cellulose concentration dependence of the ion diffusivities.

Combining variational and model-based techniques to register PET and MR images in hand osteoarthritis.

Co-registration of clinical images acquired using different imaging modalities and equipment is finding increasing use in patient studies. Here we present a method for registering high-resolution positron emission tomography (PET) data of the hand acquired using high-density avalanche chambers with magnetic resonance (MR) images of the finger obtained using a 'microscopy coil'. This allows the identification of the anatomical location of the PET radiotracer and thereby locates areas of active bone metabolism/'turnover'. Image fusion involving data acquired from the hand is demanding because rigid-body transformations cannot be employed to accurately register the images. The non-rigid registration technique that has been implemented in this study uses a variational approach to maximize the mutual information between images acquired using these different imaging modalities. A piecewise model of the fingers is employed to ensure that the methodology is robust and that it generates an accurate registration. Evaluation of the accuracy of the technique is tested using both synthetic data and PET and MR images acquired from patients with osteoarthritis. The method outperforms some established non-rigid registration techniques and results in a mean registration error that is less than approximately 1.5 mm in the vicinity of the finger joints.

High resolution magnetic resonance imaging of excised atherosclerotic carotid tissue: the effects of specimen temperature on image contrast.

Previous Magnetic Resonance (MR) studies of carotid endarterectomy (CEA) specimens have been directed at interpreting image contrast to determine plaque composition and stability. Such studies may give misleading results since it is believed that the acquired MR data is affected by the conditions used to store the excised tissue. This has been investigated in a high-resolution imaging study of the changes in contrast occurring with a change in specimen temperature. MR images were acquired from 20 CEA specimens. The initial MR examination was made within four hours of excision in tissue maintained and imaged at body temperature. Specimens were subsequently cooled and then re-examined at different times. The MR data was interpreted by comparison with histology obtained from equivalent sections. With the exception of signals arising from blood, changes in MR image contrast occurring in the 24-hour period after the CEA were relatively slight. Plaque lipid T2-weighted image intensity was initially relatively hyperintense in some samples and decreased with time on cooling reflecting a decrease in the lipid transverse (T2) relaxation time. High-resolution imaging allowed a detailed description of plaque calcification and showed that clot retraction was probably responsible for the marked change in the distribution of signals assigned to intraluminal blood. The use of high-resolution MR imaging to examine freshly excised specimens at body temperature showed previously unreported image features. This is important in the design of in vivo MR studies directed at assessing plaque stability by identifying the composition of the atheromatous tissue.

Evidence for a different anatomic basis for joint disease localization in polymyalgia rheumatica in comparison with rheumatoid arthritis.

OBJECTIVE: The anatomic basis for joint disease localization in polymyalgia rheumatica (PMR) is poorly understood. This study used contrast-enhanced and fat suppression magnetic resonance imaging (MRI) to evaluate the relationship between synovial and extracapsular inflammation in PMR and early rheumatoid arthritis (RA). METHODS: Ten patients with new-onset PMR and 10 patients with early RA underwent dynamic contrast-enhanced MRI and conventional MRI of affected metacarpophalangeal (MCP) joints. Synovitis and tenosynovitis were calculated based on the number of enhancing voxels, initial rate of enhancement, and maximal enhancement of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA). Periarticular bone erosion and bone edema were scored according to the OMERACT (Outcome Measures in Rheumatology Clinical Trials) scoring system in both groups. The degree of extracapsular Gd-DTPA enhancement was assessed in both conditions using semiquantitative scoring. RESULTS: No significant differences were seen in the volume of synovitis (P = 0.294), degree of flexor tenosynovitis (P = 0.532), periarticular erosions (P = 0.579), or degree of bone edema (P = 0.143) between RA and PMR joints. However, despite comparable degrees of synovitis, the proportion of MCP joints showing extracapsular enhancement was higher in the PMR group (100%) than in the RA group (50%) (P = 0.030). One PMR patient, but none of the RA patients, had bone edema at the capsular insertion. CONCLUSION: Despite degrees of synovitis and tenosynovitis comparable with those in RA, PMR-related hand disease is associated with prominent extracapsular changes, suggesting that inflammation in these tissues is more prominent than joint synovitis, which is common in both conditions. This suggests that the anatomic basis for joint disease localization differs between RA and PMR.

Efficacy of infliximab on MRI-determined bone oedema in psoriatic arthritis.

BACKGROUND: Psoriatic arthritis (PsA) is commonly associated with bone pathology, including entheseal new bone formation and osteolysis. On MRI, areas of active clinical involvement are represented by bone oedema and synovitis. AIM: To assess the impact of infliximab on bone oedema in PsA as shown by MRI. METHODS: 18 patients with joint swelling, psoriasis and seronegativity for rheumatoid factor received four infusions of infliximab, 3 mg/kg, in combination with methotrexate. MRI of the affected hand (12 patients) or knee joints (6 patients) was performed before and after treatment. The primary outcome was the assessment of bone oedema and synovitis at 20 weeks as shown by MRI. Secondary outcomes included the American College of Rheumatology (ACR) response criteria, psoriasis skin scores (Psoriasis Area and Severity Index (PASI)) and a quality of life measure (Psoriatic Arthritis Quality of Life (PsAQoL)). RESULTS: At baseline, bone oedema was seen in 50% of patients (seven hands and two knees) in 30% of scanned joints, and this improved or resolved in all cases in the hand joints (p = 0.018) and in one knee joint at 20 weeks. Synovitis was found to be reduced in 90% of cases on MRI. Likewise, a significant improvement in all clinical outcomes, including PASI (p = 0.003) and PsAQoL (p = 0.006) was seen at week 20. 65% (n = 11) of the patients achieved an ACR response, of whom 45% had ACR70 or above and 54% had ACR20 or ACR50. CONCLUSIONS: Infliximab treatment is associated with dramatic improvements in MRI-determined bone oedema in PsA in the short term. It remains to be determined whether infliiximib treatment is the cause for prevention of new bone formation, bone fusion or osteolysis in PsA as shown by radiography.

A high-resolution magnetic resonance imaging study of distal interphalangeal joint arthropathy in psoriatic arthritis and osteoarthritis: are they the same?

OBJECTIVE: Distal interphalangeal (DIP) joint arthropathy is characteristic of both psoriatic arthritis (PsA) and osteoarthritis (OA), but the microanatomic basis for DIP joint localization is poorly understood. This study used high-resolution magnetic resonance imaging (MRI) to investigate the basis for hand disease localization in both conditions. METHODS: Twenty patients matched for disease duration (10 with DIP joint PsA and 10 with DIP joint OA) and 10 normal control subjects were scanned with a 1.5T MRI scanner utilizing a high-resolution 23-mm diameter surface coil with displayed pixel dimensions of 80-100 mum. Images were obtained precontrast and postcontrast, and all joint structures, including ligaments, tendons, and entheses, were evaluated by 2 independent assessors. RESULTS: PsA could be distinguished from OA on the basis of more severe inflammation in the collateral ligaments and the extensor tendons and more severe changes at the corresponding DIP joint entheseal insertions. A much greater degree of extracapsular enhancement, with diffuse involvement of the nailbed and diffuse bone edema without cartilage damage, was also typical of PsA. Compared with the normal controls, the OA cohort exhibited prominent ligament and entheseal changes, but with much less contrast enhancement than in PsA and less bone involvement at the insertions. CONCLUSION: These findings suggest prominent inflammatory changes in ligament, tendon, enthesis, and adjacent bone in the DIP joint disease of PsA patients. Involvement of the same structures is common in the DIP joints of OA patients, but inflammatory changes are much less marked. These findings are potentially important for a better understanding of arthritis in humans.

High-resolution magnetic resonance imaging for the assessment of hand osteoarthritis.

OBJECTIVE: To investigate the use of a novel surface coil for clinically utilized magnetic resonance imaging (MRI) scanners, in order to describe the microanatomic basis for hand osteoarthritis (OA) at all stages of disease. METHODS: MRI of proximal or distal interphalangeal joints was performed in 58 subjects: 16 patients with early OA (symptom duration < or =12 months), 14 patients with chronic OA, 10 patients with clinically normal asymptomatic joints adjacent to arthritic joints, and 18 normal controls. High-resolution images were obtained with displayed pixel dimensions of 80-100 mum using a 1.5T scanner and a 23-mm-diameter surface coil. All joint structures were evaluated. RESULTS: The high-resolution images of every joint structure showed comparable abnormalities in both early and chronic OA, including cartilage loss, bone edema, synovial enhancement, osteophytosis, and erosions. Heberden's and Bouchard's node formation occurred at regions where soft tissue bulged through the capsule between the dorsal tendons and collateral ligaments (CLs). Prominent CL thickening or disruption (100% of OA patients) was evident even in joints where cartilage was partially preserved. Clinically normal joints adjacent to OA hand joints showed thickening and enhancement of CLs which was the most common abnormality seen (80% of OA patients). Older normal subjects showed subtle changes within the CLs. CONCLUSION: Obtaining high-resolution MR images from clinically utilized scanners represents a novel way for exploring the microanatomic basis of hand arthritis and may have considerable potential in the clinical setting. In the present evaluation in nodal OA, previously unappreciated CL abnormalities were especially common.

Regional variation and differential response to therapy for knee synovitis adjacent to the cartilage-pannus junction and suprapatellar pouch in inflammatory arthritis: implications for pathogenesis and treatment.

OBJECTIVE: To use magnetic resonance imaging (MRI) to investigate the importance of knee joint synovitis at the cartilage-pannus junction (CPJ) in rheumatoid arthritis (RA) as compared with synovitis at a distant site in the suprapatellar pouch (SPP) and as compared with CPJ synovitis in the spondylarthropathies (SpA), and to assess the relative response of knee joint synovitis to therapy at the CPJ and SPP sites. METHODS: Dynamic contrast-enhanced MRI (DEMRI) of actively involved knee joints in 24 patients (13 with RA and 11 with SpA) was undertaken. The area of synovitis was calculated at the CPJ and SPP regions of interest in patients with RA and in patients with SpA. Differences in CPJ and SPP synovitis were determined using calculated DEMRI parameters which included the initial rate of contrast enhancement (IRE) and the maximal enhancement (ME). Changes in the synovial area at the CPJ and SPP were also measured in 10 patients with early RA, following treatment with disease-modifying antirheumatic drugs (DMARDs) (either methotrexate or leflunomide). RESULTS: In patients with RA or SpA, the area of synovitis was significantly larger immediately adjacent to the CPJ compared with a distant site at the SPP (in RA, mean synovitis area 162 mm2 at the CPJ versus 114 mm2 at the SPP [P = 0.010]; in SpA, mean synovitis area 214 mm2 at the CPJ versus 143 mm2 at the SPP [P = 0.002]), but the differences in the areas of synovitis at these sites were not significant between the RA and SpA patients. The IRE and ME values were also higher at the CPJ compared with the SPP, both in the RA patients (IRE P = 0.054, ME P = 0.018) and in the SpA patients (IRE P = 0.002, ME P = 0.001). A larger reduction in the area of synovitis was seen at the SPP compared with the CPJ following DMARD therapy in the RA patients (mean reduction 35% at the SPP [P = 0.023] and 12% at the CPJ [P not significant]). CONCLUSION: The non-disease-specific variations in synovitis and the differential responses to therapy in RA patients have implications for improving our understanding of CPJ synovitis. The results suggest that the pathophysiologic events at the CPJ reflect common anatomic, immune system, or biomechanical factors that play a role in modulating the severity of arthritis, and these events are not specific to RA since the same process was observed in other arthritides.

Posterior fossa abnormalities seen on magnetic resonance brain imaging in a cohort of newborn infants.

OBJECTIVE: To describe the nature and frequency of posterior fossa (PF) lesions in infants who underwent magnetic resonance (MR) brain imaging in the neonatal period and to correlate with cranial ultrasound (CUS) findings and clinical outcome. STUDY DESIGN: A retrospective review of all neonatal MR brain imaging from 1996 to 2001 (n=558). MR images, CUS and case notes were reviewed in infants with PF abnormality. RESULTS: A total of 20 infants had abnormalities in the PF, which represents 4.7% of abnormalities seen on MR. Out of 10, six term infants had PF extra-axial hemorrhage, three had cerebellar hypoplasia, while one had cerebellar hemorrhage. In the preterm, 8/10 lesions were unilateral; focal cerebellar hemorrhage was seen in 5/10 and extensive hemorrhage with secondary atrophy in 3/10. Out of 20, 17 infants also had supratentorial lesions. Out of 20, 19 had CUS performed, of which 7/19 showed PF abnormality. CONCLUSION: Intracerebellar hemorrhage was more common in preterm infants than in term infants. These hemorrhages tended to be focal, unilateral and were associated with atrophy.

Role of metacarpophalangeal joint anatomic factors in the distribution of synovitis and bone erosion in early rheumatoid arthritis.

OBJECTIVE: To investigate the role of metacarpophalangeal (MCP) joint anatomic and biomechanical factors in the distribution of synovitis and bone erosion in early rheumatoid arthritis (RA). METHODS: Thirty-three patients with early RA with clinically diagnosed MCP joint disease and 28 healthy controls were examined by magnetic resonance imaging of the second to fifth MCP joints of the dominant hand. T1 and T2 fat-suppressed coronal sequences were obtained to assess erosion, and dynamic contrast-enhanced images were acquired to assess synovitis in all of the RA patients and in 8 of the controls. Erosions were defined as bone defects with sharp margins observed using T1-weighted imaging in 2 planes, with a cortical break seen in at least 1 plane. The location of erosions was recorded. The volume of synovitis surrounding each MCP joint (divided into 8 regions) was calculated by summation of voxels derived from the maximal enhancement parameters. The synovial volumes adjacent to MCP joint collateral ligaments were determined by correcting synovial volumes for the positions of asymmetrically placed flexor tendons. RESULTS: In patients with early RA in whom bone erosions were present, there was a propensity for involvement of the radial side of the second (P < 0.0001), third (P = 0.002), and fourth (P = 0.056) MCP joints, but not the fifth. Fifty-two of the 110 erosions (47.3%) occurred adjacent to the radial collateral ligaments of the second, third, and fourth MCP joints. The volume of synovitis was also greater on the radial side of the second (P < 0.0001) and third (P < 0.001) MCP joints. A predilection for synovitis in all of the MCP joints adjacent to the radial collateral ligaments was evident when the positional effects of the flexor tendon were considered. The position of radial collateral ligaments had an effect on erosion formation that was independent of synovitis. A predilection for radial bone damage was also evident in the controls, although lesions were 5-fold less frequent, were generally smaller, and had well-defined margins. CONCLUSION: This study shows that there is a predilection for both synovitis and bone erosion formation on the radial side of the MCP joints in early RA, and that joint inflammation appears to drive the inherent tendency for bone damage on the radial side of joints. These findings have implications regarding the pathogenesis of joint damage in RA.