Contrast-enhanced MR myelography in spontaneous intracranial hypotension: description of an artefact imitating CSF leakage

In contrast-enhanced (CE) MR myelography, hyperintense signal outside the intrathecal space in T1-weighted sequences with spectral presaturation inversion recovery (SPIR) is usually considered to be due to CSF leakage. We retrospectively investigated a hyperintense signal at the apex of the lung appearing in this sequence in patients with SIH (n = 5), CSF rhinorrhoea (n = 2), lumbar spine surgery (n = 1) and in control subjects (n = 6). Intrathecal application of contrast agent was performed in all patients before MR examination, but not in the control group. The reproducible signal increase was investigated with other fat suppression techniques and MR spectroscopy. All patients and controls showed strongly hyperintense signal at the apex of the lungs imitating CSF leakage into paraspinal tissue. This signal increase was identified as an artefact, caused by spectroscopically proven shift and broadening of water and lipid resonances (1–2 ppm) in this anatomical region. Only patients with SIH showed additional focal enhancement along the spinal nerve roots and/or in the spinal epidural space. In conclusion CE MR myelography with spectral selective fat suppression shows a reproducible cervicothoracic artefact, imitating CSF leakage. Selective water excitation technique as well as periradicular and epidural contrast collections may be helpful to discriminate between real pathological findings and artefacts.     

Radiological features of superomedial iliac insufficiency fractures: a possible mimicker of metastatic disease

Objective  Pelvic insufficiency fractures are common in elderly patients. Because both osteoporosis and metastatic disease occur in similar patient populations, insufficiency fractures may be mistaken for metastatic foci. Although the ilium is not an uncommon location for metastases, insufficiency fractures rarely involve the ilium. The radiological features of insufficiency fractures adjacent to the sacroiliac joint (superomedial ilium) have not been well described. We describe the computed tomography (CT), magnetic resonance (MR), and positron emission tomography (PET) imaging findings of these rare fractures. Materials and methods  Six patients (five female, one male; mean age 66 years, age range 47–83 years) with iliac insufficiency fractures adjacent to the sacroiliac joint were identified following retrospective review of a clinical database. Imaging studies, including CT (n = 4), MR (n = 3), and PET (n = 2) were reviewed by two radiologists. Tissue biopsy result was available in one patient. Results  CT demonstrated subtle fracture lucency (n = 2) or linear sclerosis (n = 3) adjacent to the sacroiliac joint; MR marrow changes adjacent to the sacroiliac joint demonstrated a low T1, high T2 signal intensity line (n = 2), or a low T1 and low T2 signal intensity line (n = 1). Fractures were fluorodeoxyglucose avid (n = 2) with average SUV_max 2.2. Iliac fractures were bilateral in three patients; additional pelvic insufficiency fractures were present in one patient. In one patient, CT-guided biopsy showed no evidence of malignancy. Conclusion  Recognition of the radiological characteristics of iliac insufficiency fractures is important in order to distinguish them from malignancy. The presence of additional pelvic fractures in characteristic locations in the setting of osteoporosis may help to confirm the diagnosis.     

Small hypervascular hepatocellular carcinomas: value of “washout” on gadolinium-enhanced dynamic MR imaging compared to superparamagnetic iron oxide-enhanced imaging

The aim of this study was to retrospectively compare the value of “washout” on dynamic MR imaging with superparamagnetic iron oxide (SPIO)-enhanced imaging features of small hepatocellular carcinoma (HCC). A total of 74 small (5–30 mm) hypervascular HCCs in 42 cirrhotic patients who underwent double contrast material-enhanced MR imaging were evaluated to determine the presence of washout in the portal or equilibrium phase of gadolinium-enhanced dynamic imaging and decreased uptake of SPIO on T2*-weighted imaging. HCCs were verified histologically (n = 13) or by serial follow-up imaging studies (n = 61). According to the size of the lesions, 27 vs. 73% (<10 mm, n = 15; P = 0.016 on McNemar test), 39 vs. 79% (10–14 mm, n = 28; P = 0.002), 50 vs. 93% (15–20 mm, n = 14; P = 0.031), and 82 vs. 100% (>20 mm, n = 17; P = 0.250) of the lesions showed washout vs. decreased SPIO accumulation respectively. The larger the lesion, the higher the prevalence of washout or decreased SPIO uptake (P = 0.004 or P = 0.036, respectively, on Mantel-Haenszel test). In many small hypervascular HCCs up to 2 cm, SPIO-enhanced MR imaging offers essential information for early diagnosis in the absence of washout on dynamic imaging.     

Adrenal metastases: CT-guided and MR-thermometry-controlled laser-induced interstitial thermotherapy

The aim of the study was to evaluate the feasibility, safety and effectiveness of CT-guided and MR-thermometry-controlled laser-induced interstitial thermotherapy (LITT) in adrenal metastases. Nine patients (seven male, two female; average age 65.0 years; range 58.7–75.0 years) with nine unilateral adrenal metastases (mean diameter 4.3 cm) from primaries comprising colorectal carcinoma (n = 5), renal cell carcinoma (n = 1), oesophageal carcinoma (n = 1), carcinoid (n = 1), and hepatocellular carcinoma (n = 1) underwent CT-guided, MR-thermometry-controlled LITT using a 0.5 T MR unit. LITT was performed with an internally irrigated power laser application system with an Nd:YAG laser. A thermosensitive, fast low-angle shot 2D sequence was used for real-time monitoring. Follow-up studies were performed at 24 h and 3 months and, thereafter, at 6-month intervals (median 14 months). All patients tolerated the procedure well under local anaesthesia. No complications occurred. Average number of laser applicators per tumour: 1.9 (range 1–4); mean applied laser energy 33 kJ (range 15.3–94.6 kJ), mean diameter of the laser-induced coagulation necrosis 4.5 cm (range 2.5–7.5 cm). Complete ablation was achieved in seven lesions, verified by MR imaging; progression was detected in two lesions in the follow-up. The preliminary results suggest that CT-guided, MR-thermometry-controlled LITT is a safe, minimally invasive and promising procedure for treating adrenal metastases.     

Differentiating high-grade from low-grade chondrosarcoma with MR imaging

The purpose of the study was to evaluate the MR imaging features that differentiate between low-grade chondrosarcoma (LGCS) and high-grade chondrosarcoma (HGCS) and to determine the most reliable predictors for differentiation. MR images of 42 pathologically proven chondrosarcomas (28 LGCS and 14 HGCS) were retrospectively reviewed. There were 13 male and 29 female patients with an age range of 23–72 years (average age 51 years). On MR images, signal intensity, specific morphological characteristics including entrapped fat, internal lobular architecture, and outer lobular margin, soft tissue mass formation and contrast enhancement pattern were analysed. MR imaging features used to identify LGCS and HGCS were compared using univariate analysis and multivariate stepwise logistic regression analysis. On T1-weighted images, a central area of high signal intensity, which was not seen in LGCS, was frequently observed in HGCS (n = 5, 36%) (p < 0.01). Entrapped fat within the tumour was commonly seen in LGCS (n = 26, 93%), but not in HGCS (n = 1, 4%) (p < 0.01). LGCS more commonly (n = 24, 86%) preserved the characteristic internal lobular structures within the tumour than HGCSs (n = 4, 29%) (p < 0.01). Soft tissue formation was more frequently observed in HGCS (n = 11, 79%) than in LGCS (n = 1, 4%) (p < 0.01). On gadolinium-enhanced images, large central nonenhancing areas were exhibited in only two (7.1%) of LGCS, while HGCS frequently (n = 9, 64%) had a central nonenhancing portion (p < 0.01). Results of multivariate stepwise logistic regression analysis showed that soft tissue formation and entrapped fat within the tumour were the variables that could be used to independently differentiate LGCS from HGCS. There were several MR imaging features of chondrosarcoma that could be helpful in distinguishing HGCS from LGCS. Among them, soft tissue mass formation favoured the diagnosis of HGCS, and entrapped fat within the tumour was highly indicative of LGCS.     

Chronic medial knee pain without history of prior trauma: correlation of pain at rest and during exercise using bone scintigraphy and MR imaging

Objective  The objective of this study was to correlate chronic medial knee pain at rest and during exercise with bone scintigraphic uptake, bone marrow edema pattern (BMEP), cartilage lesions, meniscal tears, and collateral ligament pathologies on magnetic resonance MR imaging (MRI). Materials and methods  Fifty consecutive patients with chronic medial knee pain seen at our institute were included in our study. Pain level at rest and during exercise was assessed using a visual analog scale (VAS). On MR images, BMEP volume was measured, and the integrity of femoro-tibial cartilage, medial meniscus, and medial collateral ligament (MCL) were assessed. Semiquantitative scintigraphic tracer uptake was measured. Multivariate linear regression analysis was performed. Results  At the day of examination, 40 patients reported medial knee pain at rest, 49 when climbing stairs (at rest mean VAS 33 mm, range 0–80 mm; climbing stairs mean VAS, 60 mm, range 20–100 mm). Bone scintigraphy showed increased tracer uptake in 36 patients (uptake factor, average 3.7, range 2.4–18.0). MRI showed BMEP in 31 studies (mean volume, 4,070 mm³; range, 1,200–39,200 mm³). All patients with BMEP had abnormal bone scintigraphy. Ten percent of patients with pain at rest and 8% of patients with pain during exercise showed no BMEP but tracer uptake in scintigraphy. Tracer uptake and signal change around MCL predicted pain at rest significantly (tracer uptake p = 0.004; MCL signal changes p = 0.002). Only MCL signal changes predicted pain during exercise significantly (p = 0.001). Conclusion  In chronic medial knee pain, increased tracer uptake in bone scintigraphy is more sensitive for medial knee pain than BMEP on MRI. Pain levels at rest and during exercise correlate with signal changes in and around the MCL.     

MRI features of tuberculosis of the knee

Objective  The objective of this study was to describe the magnetic resonance imaging (MRI) features of tuberculosis (TB) of the knee joint. Materials and methods  The MRI features in 15 patients with TB of the knee, as confirmed by histology of the biopsied joint synovium, were reviewed retrospectively. The images were assessed for intra-articular and peri-articular abnormalities. Results  All patients had florid synovial proliferation. The proliferating synovium showed intermediate to low T2 signal intensity. In the patients who were administered intravenous contrast, the hypertrophic synovium was intensely enhancing. Marrow edema (n = 9), osteomyelitis (n = 4), cortical erosions (n = 5), myositis (n = 6), cellulitis (n = 2), abscesses (n = 3), and skin ulceration/sinus formation (n = 2) were seen in the adjacent bone and soft tissue. Conclusion  Synovial proliferation associated with tuberculous arthritis is typically hypointense on T2-weighted images. This appearance, in conjunction with other peri-articular MRI features described, can help in distinguishing TB arthritis from other proliferating synovial arthropathies.     

Whole-body CT in polytrauma patients: effect of arm positioning on thoracic and abdominal image quality

The purpose of this study is to assess the influence of different arm positioning techniques on thoracic and abdominal image quality and radiation dose of whole-body trauma CT (wbCT). One hundred and fifty polytrauma patients (104 male, mean age 47 ± 19) underwent wbCT with arms elevated above the head (group A, n = 50), alongside the abdomen (group B, n = 50), and on a pillow ventrally to the chest with both arms flexed (group C, n = 50). Two blinded, independent observers measured image noise and rated image quality (scores 1–3) of the liver, aorta, spleen, spine, and lower lungs. Radiation dose parameters were noted, and the abdomens’ anterior–posterior diameter and scan lengths were measured. Interreader agreements for image noise (r = 0.86; p < 0.001) and subjective image quality (k = 0.71–0.84) were good. Noise was lower (p < 0.05), image quality of the liver, aorta, spleen, and spine was higher, and radiation dose lower in group A than in groups B and C (p < 0.001, each). Image quality of the spleen, liver, and aorta were higher in group C than in group B (p < 0.05, each). No significant differences in scan length (p = 0.61) were found among groups. Abdominal anterior–posterior diameter correlated significantly with noise (r = 0.82; p < 0.01) and dose (r = 0.47; p < 0.001). Estimated effective radiation doses were significantly (p < 0.001) higher in groups B (21.2 mSv) and C (21.9 mSv) as compared to A (16.1 mSv). In wbCT for polytrauma patients, positioning of the arms above the head results in better image quality and lower radiation dose. Placing the flexed arms on a large pillow ventrally to the chest significantly improves image quality as compared to positioning alongside the abdomen.     

USPIO-enhanced MR imaging of macrophage infiltration in native and transplanted kidneys: initial results in humans

The purpose of this study was to evaluate the detection and characterization of macrophage infiltration in native and transplanted kidneys using ultrasmall superparamagnetic iron oxide particles (USPIO). Among 21 patients initially enrolled, 12 scheduled for renal biopsy for acute or rapidly progressive renal failure (n = 7) or renal graft rejection (n = 5) completed the study. Three magnetic resonance (MR) sessions were performed with a 1.5-T system, before, immediately after and 72 h after i.v. injection of USPIO at doses of 1.7–2.6 mg of iron/kg. Signal intensity change was evaluated visually and calculated based on a region of interest (ROI) positioned on the kidney compartments. Histological examination showed cortical macrophage infiltration in four patients (>5 macrophages/mm²), two in native kidneys (proliferative extracapillary glomerulonephritis) and two in transplants (acute rejection). These patients showed a 33 ± 18% mean cortical signal loss on T2*-weighted images. In the remaining eight patients, with <5 macrophages/mm², there was no cortical signal loss. However, in three of these, presenting with ischemic acute tubular necrosis, a strong (42 ± 18%) signal drop was found in the medulla exclusively. USPIO-enhanced MR imaging can demonstrate infiltration of the kidneys by macrophages both in native and transplanted kidneys and may help to differentiate between kidney diseases.     

Emergency MRI of acute pelvic pain: MR protocol with no oral contrast

The aim of this study was to evaluate the efficacy of magnetic resonance (MR) without oral contrast in the assessment of suspected acute pathologies of the pelvis in pregnant and non-pregnant patients. Sixty-seven patients who had MR of the lower abdomen and pelvis for acute abdomen were included in the study. The MR examinations were evaluated for indication of the study, type of MR sequences, and sensitivity of MR in diagnosing the disease. T2 single shot fast spin echo (SS-FSE), T2 FSE, short tau inversion recovery, pre-gadolinium T1, and post-gadolinium T1 sequences were utilized. There were 30 pregnant and two postpartum women in the study group. Positive pelvic MR findings were seen in 73% (49/67). Final diagnoses were acute appendicitis (n = 12), ovarian torsion (n = 6), abscess (n = 3), tubo-ovarian abscess (n = 2), ovarian tumor (n = 2), degenerating fibroid (n = 3), and perianal fistula (n = 2). For acute appendicitis, sensitivity was 100% (12/12), and positive predictive value was 92% (12/13). Post-gadolinium T1-weighted sequences and T2 SS-FSE with FS were the sequences, which were most likely to best demonstrate the acute appendicitis. For ovarian torsion, the sensitivity was 86% (6/7), and positive predictive value was 100% (6/6). MR imaging is an efficacious means of diagnosing acute appendicitis, ovarian torsions, and other adnexal diseases in the acute setting. The four sequence protocol without oral contrast offers an excellent means of investigating the cause of acute lower abdominal and pelvic pain.     

Ultrasound and MRI findings in appendicular and truncal fat necrosis

Objective The objective was to evaluate ultrasound and MRI in clinical appendicular and truncal fat necrosis. Materials and methods Thirty-three patients (14 men, 19 women, median age 55, range 29–95) were retrospectively evaluated. Histologically, three groups were seen: Group 1 (n = 18) consisted of patients with subcutaneous masses with septal and extrinsic oedema; in Group 2 (n = 11) necrosis occurred within lipomatous tumours and little oedema; and in Group 3 (n = 4) there were large complex masses consistent with Morel-Lavallée lesions. Two experienced radiologists reviewed MR (n = 30) and ultrasound (n = 32) images with consensus agreement. MRI was performed on a 1.5T system with T1-weighted, T2-weighted fat-suppressed and T1-weighted fat-suppressed post-intravenous gadolinium sequences obtained in two orthogonal planes. Ultrasound (linear 5- to 13.5-MHz probe) was performed in the longitudinal and short axis. Anatomical position, size, shape (oval, linear, ill-defined), internal architecture (lobules, septi or stranding), intrinsic signal characteristics, presence of surrounding pseudocapsule, extrinsic linear stranding and vascularity (gadolinium enhancement or power Doppler) were recorded. Results Anatomical locations were buttock/thigh (n = 17), leg (n = 6), upper limb (n = 5) and thoracic/abdominal wall (n = 5) with the majority of lesions (30 out of 33) oval/linear in shape. On ultrasound and MRI most lesions showed internal fat lobules, intervening septi and a surrounding pseudocapsule. Conclusion Fat necrosis can usually be identified as containing multiple fat lobules on ultrasound and MRI despite a varying degree of inflammatory change surrounding and within the mass.     

Combined use of T2-weighted and diffusion-weighted 3-T MR imaging for differentiating uterine sarcomas from benign leiomyomas

The objective of our study was to compare diffusion-weighted imaging (DWI) alone and DWI combined with T2-weighted MRI for the differentiation of uterine sarcomas from benign leiomyomas. T2-weighted imaging and DWI were performed in 103 patients with 103 myometrial tumours, including 8 uterine sarcomas and 95 benign leiomyomas on 3-T MR imaging. The signal intensity (SI) of the tumour on T2-weighted images was quantified as the tumour–myometrium contrast ratio (TCR) by using the following formula: (SI_tumour − SI_myometrium)/SI_myometrium. The TCR or apparent diffusion coefficient (ADC) value alone and then the ADC value combined with T2-weighted imaging were evaluated for differentiation between sarcomas and leiomyomas. The mean ADC value of sarcomas was 0.86 ± 0.11 × 10⁻³ m²/s, which was significantly lower than that of leiomyomas 1.18 ± 0.24 × 10⁻³ m²/s; however, there was a substantial overlap. The mean TCR of sarcomas was 0.66 ± 0.71, which was significantly higher than that of the leiomyomas, –0.37 ± 0.34; however, again, there was a considerable overlap. When ADC was less than 1.05 × 10⁻³ mm²/s and TCR was greater than 0 this condition was considered to confirm a sarcoma; a combination of ADC and TCR achieved a significant improvement without any overlap between sarcomas and leiomyomas (sensitivity 100%, specificity 100%). Our preliminary results indicate that combined DWI and T2-weighted MR imaging is better than DWI alone in the differentiation of uterine sarcomas from benign leiomyomas.     

Contribution of diffusion-weighted MR imaging for predicting benignity of complex adnexal masses

The purpose of this study was to prospectively assess the contribution of diffusion-weighted MR imaging (DWI) for characterizing complex adnexal masses. Seventy-seven women (22–87 years old) with complex adnexal masses (30 benign and 47 malignant) underwent MR imaging including DWI before surgery. Conventional morphological MR imaging criteria were recorded in addition to b _1,000 signal intensity and apparent diffusion coefficient (ADC) measurements of cystic and solid components. Positive likelihood ratios (PLR) were calculated for predicting benignity and malignancy. The most significant criteria for predicting benignity were low b _1,000 signal intensity within the solid component (PLR = 10.9), low T2 signal intensity within the solid component (PLR = 5.7), absence of solid portion (PLR = 3.1), absence of ascites or peritoneal implants (PLR = 2.3) and absence of papillary projections (PLR = 2.3). ADC measurements did not contribute to differentiating benign from malignant adnexal masses. All masses that displayed simultaneously low signal intensity within the solid component on T2-weighted and on b _1,000 diffusion-weighted images were benign. Alternatively, the presence of a solid component with intermediate T2 signal and high b _1,000 signal intensity was associated with a PLR of 4.5 for a malignant adnexal tumour. DWI signal intensity is an accurate tool for predicting benignity of complex adnexal masses.     

Longitudinal changes in rheumatoid arthritis after rituximab administration assessed by quantitative and dynamic contrast-enhanced 3-T MR imaging: preliminary findings

We retrospectively assessed the longitudinal changes of rheumatoid arthritis under rituximab therapy by use of quantitative and dynamic contrast-enhanced 3-T magnetic resonance (MR) imaging of the metacarpophalangeal joints of 10 patients at baseline and 26 weeks (n = 10). Additional studies were available at 12 weeks (n = 9) and at 52 weeks (n = 5). Clinical activity was assessed by use of the 28-joint disease activity score (DAS28). MR imaging was used to assess volumes of synovial enhancement, osseous enhancement, and erosions and early rapid enhancement. DAS28 and serum C-reactive protein trended down over time and were significantly lower at 26 weeks. Volume of synovial enhancement and early rapid enhancement showed a significant minimum at 26 weeks and increased thereafter. The erythrocyte sedimentation rate paralleled these two trends. Osseous enhancement did not significantly change over time. Erosions showed a significant progression. Trends of DAS28 and erosions were significantly different (P = 0.0075). In conclusion, our preliminary results suggest that rituximab is associated with a decrease of the inflammatory activity of synovitis with a minimum at 26 weeks and increasing activity thereafter suggesting recurrence. Our results further suggest subclinical progression of erosions with an inverse relationship to decreasing disease activity scores. Further studies are needed to confirm these results.     

Protocol for measuring myocardial blood flow by PET/CT in cats

Purpose  The aim of this study was to establish a protocol for measuring myocardial blood flow (MBF) by PET/CT in healthy cats. The rationale was its future use in Maine Coon cats with hypertrophic cardiomyopathy (HCM) as a model for human HCM. Methods  MBF was measured in nine anaesthetized healthy cats using a PET/CT scanner and ¹³NH₃ at rest and during adenosine infusion. Each cat was randomly assigned to receive vasodilator stress with two or three adenosine infusions at the following rates (μg/kg per minute): 140 (Ado 1, standard rate for humans), 280 (Ado 2, twice the human standard rate), 560 (Ado 4), 840 (Ado 6) and 1,120 (Ado 8). Results  The median MBF at rest was 1.26 ml/min per g (n = 9; range 0.88–1.72 ml/min per g). There was no significant difference at Ado 1 (n = 3; median 1.35, range 0.93–1.55 ml/min per g; ns) but MBF was significantly greater at Ado 2 (n = 6; 2.16, range 1.35–2.68 ml/min per g; p < 0.05) and Ado 4 (n = 6; 2.11, 1.92–2.45 ml/min per g; p < 0.05). Large ranges of MBF values at Ado 6 (n = 4; 2.53, 2.32–5.63 ml/min per g; ns) and Ado 8 (n = 3; 2.21, 1.92–5.70 ml/min per g; ns) were noted. Observed adverse effects, including hypotension, AV-block and ventricular premature contractions, were all mild, of short duration and immediately reversed after cessation of the adenosine infusion. Conclusion  MBF can be safely measured in cats using PET. An intravenous adenosine infusion at a rate of 280 μg/kg per minute seems most appropriate to induce maximal hyperaemic MBF response in healthy cats. Higher adenosine rates appear less suitable as they are associated with a large heterogeneity in flow increase and rate pressure product, most probably due to the large variability in haemodynamic and heart rate response.     

High-resolution MR imaging of periarterial edema associated with biological inflammation in spontaneous carotid dissection

It has been suggested that spontaneous cervical carotid artery dissection (sCAD) may result from arterial inflammation. Periarterial edema (PAE), occasionally described in the vicinity of the mural hematoma in patients with sCAD, may support this hypothesis. Using cervical high-resolution magnetic resonance imaging, three readers, blinded to the mechanism of carotid artery dissection, searched for PAE, defined as periarterial T2-hyperintensity and T1-hypointensity, in 29 consecutive CAD patients categorized as spontaneous CAD (sCAD, n = 18) or traumatic CAD (tCAD, n = 11; i.e., major head or neck trauma within 2 weeks before the clinical onset). The relationships between PAE, inflammatory biological markers, history of infection and CAD mechanism were explored. Multiple CADs (n = 8) were found only in sCAD patients. Compared with tCAD, patients with sCAD were more likely to have a recent history of infection (OR = 12.5 [_95%CI = 1.3–119], p = 0.03), PAE (83% vs. 27%; OR = 13.3 [_95%CI = 2.2–82.0], p = 0.005) and to have elevated CRP (OR = 6.1 [_95%CI = 1.2–32.1], p = 0.0002) or ESR (OR = 8.8 [_95%CI = 1.5–50.1], p = 0.002) values. Interobserver agreement was 0.84 or higher for PAE identification. sCAD was associated with PAE and biological inflammation. Our results support the hypothesis of an underlying arterial inflammation in sCAD.     

Measurement of spinal canal narrowing,interpedicular widening,and vertebral compression in spinal burst fractures: plain radiographs versus multidetector computed tomography

Objective  To assess the reliability of measurements of spinal canal narrowing, vertebral body compression, and interpedicular widening in burst fractures in radiography compared with multidetector computed tomography (MDCT). Materials and methods  Patients who had confirmed acute vertebral burst fractures over an interval of 34 months underwent both MDCT and radiography. Measurements of spinal canal narrowing, vertebral body compression, and interpedicular widening from MDCT and radiography were compared. Results  The 108 patients (30 female, 78 male, aged 16–79 years, mean 39 years) had 121 burst fractures. Eleven patients had multiple fractures, of which seven were not contiguous. Measurements showed a strong positive correlation between radiography and MDCT (Spearman’s rank sum test: spinal canal narrowing k = 0.50–0.82, vertebral compression k = 0.55–0.72, and interpedicular widening k = 0.81–0.91, all P < 0.05), except for the cervical spine (k = −0.50 to 0.61, with all P > 0.25) and for interpedicular widening in the thoracic spine (k = 0.35, P = 0.115). The average difference in measurements between the modalities was 3 mm or fewer. Conclusion  Radiography demonstrates interpedicular widening, spinal canal narrowing and vertebral compression with acceptable precision, with the exception of those of the cervical spine.     

Use of decrease in apparent diffusion coefficient values to predict infarct age

The purpose of the study was to determine the ability to predict infarct age based on decrease in apparent diffusion coefficient (ADC) values. We retrospectively identified 94 individuals (age range 16 years to 91 years; mean 63.7 + 14.1 years) who underwent magnetic resonance diffusion-weighted imaging at our institution over a course of 14 months whose infarct age could be reliably determined within 1 h. A single observer measured ADC values within the center of the infarct and compared them against values in contralateral normal tissue. We examined the ability of four ADC decrease thresholds (i.e., >50%, >40%, >30%, and >20%) to predict infarct age of <24 and <48 h. Levels of ADC decrease in infarcts were as follows: <20%, n = 9; 20–29%, n = 21; 30–39%, n = 25; 40–49%, n = 23; >50%, n = 16. For prediction of infarct age <24 h, sensitivity for the four ADC decrease thresholds ranged from 25% to 94%, specificity ranged from 10% to 85%, positive predictive value (PPV) ranged from 18% to 25%, and negative predictive value (NPV) ranged from 85% to 89%. For prediction of infarct age <48 h, sensitivity ranged from 23% to 98%, specificity ranged from 15% to 87%, PPV ranged from 46% to 56%, and NPV ranged from 60% to 89%. Test performance characteristics for predicting infarct age of <24 and <48 h were relatively poor. In particular, PPV was very low for predicting infarcts <24 h old.     

MR-guided liver biopsy within a short, wide-bore 1.5 Tesla MR system

The purpose of this study was to evaluate the diagnostic efficacy of magnetic resonance (MR)-guided biopsy of focal liver lesions within a short, wide-bore 1.5-T MR system and to determine the duration and accuracy of needle placement using MR fluoroscopy guidance in 25 patients. Accuracy of needle placement was evaluated in two orthogonal planes, and the out-of-plane angle of needle deflection was measured. Needle positioning was characterised subjectively as centred, peripheral, or exterior relative to the lesion. Exterior positioning was corrected by a step-by-step procedure. Surgical resection (n = 6), previous histologies (n = 8), or clinical/radiological follow-up (n = 11) served as the ‘gold standard’. The guidance needle could be placed successfully using MR fluoroscopy in 20 of 25 patients (80%). Needle placement was rated as ‘centred’ in 11 and as ‘peripheral’ in nine patients. Median needle deflection was 2.6 degrees, with a median deviation of 3.4 mm. In five patients, the direct approach failed or was rated as ‘exterior’; therefore, repositioning after needle stabilisation with a stainless-steel stylet was necessary. The diagnostic yield of all biopsies was: sensitivity 95.5%, specificity 100.0% and accuracy 96.0%. In conclusion, MR-guided biopsies in a short, wide-bore MR system yielded highly reliable biopsy results, and in most cases the direct approach with MR fluoroscopy guidance proved to be fast and accurate.     

MRI findings of juvenile psoriatic arthritis

Objective  The aim of this study was to describe the magnetic resonance imaging (MRI) features of juvenile psoriatic arthritis (JpsA) in children in order to facilitate early diagnosis and proper management. Materials and methods  Two pediatric radiologists retrospectively reviewed in consensus a total of 37 abnormal MRI examinations from 31 pediatric patients (nine boys, 22 girls; age range 1–17 years; mean age 9.4 years) who had a definite diagnosis of JpsA and underwent MRI. Each MRI was evaluated for synovium abnormality (thickening and enhancement), joint effusion (small, moderate, and large), bone marrow abnormality (edema, enhancement, and location of abnormality), soft tissue abnormality (edema, enhancement, atrophy, and fatty infiltration), tendon abnormality (thickening, edema, tendon sheath fluid, and enhancement), and articular abnormality (joint space narrowing and erosion). The distribution of abnormal MRI findings among the six categories for the 37 MRI examinations was evaluated. The number of abnormal MRI findings for each MRI examination was assessed. Age at MRI examination and all six categories of abnormal MRI findings according to gender were evaluated. Results  There were a total 96 abnormal MRI findings noted on 37 abnormal MRI examinations from 31 pediatric patients. The 37 abnormal MRI examinations included MRI of the hand (n = 8), knee (n = 8), ankle (n = 5), pelvis (n = 5), temporomandibular joint (n = 4), wrist (n = 3), foot (n = 2), elbow (n = 1), and shoulder (n = 1). Twenty-eight diffuse synovial thickening and/or enhancement were the most common MRI abnormality (29.2%). Joint effusion comprised 22 abnormal MRI findings (22.9%). There were 16 abnormal MRI bone marrow edema and/or enhancement findings (16.7%), and in seven (7.3%) the edema involved non-articular sites. Soft tissue abnormality manifested as edema and/or enhancement constituted 14 abnormal MRI findings (14.5%). There were ten MRI abnormalities (10.4%) involving tendons. Articular abnormality seen as joint space narrowing and/or bone erosion comprised six abnormal MRI findings (6.2%). Most MRI examinations had more than one abnormal finding (84%). Age at which MRI examinations were performed was not significantly different between boys and girls. All six categories of abnormal MRI findings were not significantly different between boys and girls. Conclusion  Children with JpsA typically present with more than one abnormal finding on their MRI studies. While synovial abnormality is the most common MR finding in children with JpsA, multi-focal bone marrow edema and enhancement at both articular and non-articular sites are also notable findings in children with JpsA. The rate of articular abnormality is much lower in children with JpsA in comparison to adults with psoriatic arthritis. Our findings suggest that MRI can play a useful role in the diagnosis and ongoing assessment of this uncommon, though important, pediatric rheumatologic disorder.