Post-gadolinium Images Research Articles

Preliminary Investigation of Adaptive Glioblastoma Radiation Therapy Using the Integrated High-Field MRI-LINAC

The MRL has the potential to visualize changes in glioblastoma (GBM) tumor volume over the course of radiotherapy. We hypothesize that the MRL can adapt for tumor volume changes observable with MRI at time of treatment. As part of a prospective ethics-board approved imaging study, MR images of GBM patients receiving 60 Gy in 30 fractions are acquired at 4 time points: Day0 (planning), Day10 (post ten fractions), Day20 and at 1-month follow-up. Using the T1-weighted post-gadolinium injection images, the enhancing volume indicating the gross tumor volume (GTV) was contoured by an experienced radiation oncologist at each time point for 3 of 20 planned patients. Relative and absolute volume changes in GTV were measured. Plan adaptation feasibility was tested in one case by simulating a new planning target volume (PTV) based on the changed GTV and then using the Adapt Plan workflow in the Monaco MRL research planning system version 5.19.02 (Elekta AB, Stockholm, Sweden) to warp the beam apertures to the new PTV. For 2 of the 3 patients analyzed the GTV shrunk by 14% and 20% at Day20 and 51% and 42% at 1 month when compared to the original GTV. For the third patient, an increase in GTV of 37% was observed at Day20. In the case of GTV reduction, the enhancing region tended to shrink in medially from within the brain towards the surgical entry point. The image set containing the 20% GTV shrinkage at Day20 was used to generate the adapted plan with the new PTV being 31% smaller than the original. The resulting beam apertures were correspondingly reduced to the shape of the new PTV by a mean of 22% (18cm2). The reduction in beam aperture area followed by warm-start optimization maintained coverage of the new PTV while reducing the maximum dose to the brainstem and optic chiasm by 37% and 39% respectively for the fractions that would receive the adapted plan. We are continuing to gather novel data related to volumetric changes in GBM tumor volume over the course of radiotherapy. Preliminary observations indicate unidirectional changes over time continuing to occur throughout and after the course of radiotherapy. Preliminary findings also indicate the feasibility of adapting for observed tumor changes and ongoing work is being undertaken to develop an adaptive strategy for the MRL that involves auto-segmentation and planning boost doses with similar or improved safety profile compared to our current standard.

Accurate late gadolinium enhancement prediction by early T1- based quantitative synthetic mapping

ObjectivesEarly synthetic gadolinium enhancement (ESGE) imaging from post-contrast T1 mapping after adenosine stress-perfusion cardiac magnetic resonance (CMR) was compared to conventional late gadolinium enhancement (LGE) imaging for assessing myocardial scar.MethodsTwo hundred fourteen consecutive patients suspected of myocardial ischaemia were referred for stress-perfusion CMR. Myocardial infarct volume was quantified on a per-subsegment basis in both synthetic (2–3 min post-gadolinium) and conventional (9 min post-gadolinium) images by two independent observers. Sensitivity, specificity, PPV and NPV were calculated on a per-patient and per-subsegment basis.ResultsBoth techniques detected 39 gadolinium enhancement areas in 23 patients. The median amount of scar was 2.0 (1.0–3.1) g in ESGE imaging and 2.2 (1.1–3.1) g in LGE imaging (p=0.39). Excellent correlation (r=0.997) and agreement (mean absolute difference: -0.028±0.289 ml) were found between ESGE and LGE images. Sensitivity, specificity, PPV and NPV of ESGE imaging were 96 (78.9–99.9), 99 (97.1–100.0)%, 96 (76.5–99.4) and 99.5 (96.6–99.9) in patient-based and 99 (94.5–100.0), 100 (99.9–100.0)%, 97.0 (91.3–99.0) and 100.0 (99.8–100.0) in subsegment-based analysis.ConclusionESGE based on post-contrast T1 mapping after adenosine stress-perfusion CMR imaging shows excellent agreement with conventional LGE imaging for assessing myocardial scar, and can substantially shorten clinical acquisition time.Key Points• Synthetic gadolinium enhancement images can be used for detection of myocardial scar.• Early synthetic gadolinium enhancement images can substantially shorten clinical acquisition time.• ESGE has high diagnostic accuracy as compared to conventional late gadolinium enhancement.• Quantification of myocardial scar with ESGE closely correlates with conventional LGE.• ESGE after stress perfusion CMR avoids need for additional gadolinium administration.

Measurement of the normal feline pituitary gland in brachycephalic and mesocephalic cats.

Objectives The purpose of this study was to determine differences in normal feline pituitary dimensions in brachycephalic and mesocephalic cats as a basis for establishing cryohypophysectomy in cats. Methods Measurements were performed on sagittal T2-weighted and transverse post-gadolinium T1-weighted or T1 3D fast field echo-weighted MRI images. A total of 32 brachycephalic and 27 mesocephalic cats were examined. Inter-observer reproducibility was assessed by t-test and Bland-Altman analysis. Results The cats were 0.6-15.9 years of age with a body weight range of 1.84-6.60 kg. For brachycephalic cats, the mean pituitary gland sagittal height was 2.15 ± 0.15 mm, pituitary gland transverse height was 2.42 ± 0.21 mm, pituitary gland transverse width was 4.44 ± 0.27 mm and pituitary gland sagittal length was 3.14 ± 0.30 mm. In mesocephalic cats, the pituitary gland dimensions were 2.94 ± 0.16 mm, 3.09 ± 0.26 mm, 4.73 ± 0.31 mm and 4.88 ± 0.30 mm for pituitary gland sagittal height, transverse height, transverse width and sagittal length, respectively. There was a highly significant correlation between brachycephalic and mesocephalic cats and pituitary gland height and length ( P <0.0001), respectively. Sex also had an effect on pituitary gland measurements. Neutering status had no significant effect on hypophyseal measurements. Age had a significant influence on pituitary gland height, width and length in the brachycephalic population. Inter-observer reproducibility was good to excellent. Conclusions and relevance The different pituitary measurements in brachycephalic and mesocephalic cats has to be considered if surgery comes into question. There are ranges in pituitary gland sizes, even among the mesocephalic cat population. Thus, exact measuring of the pituitary gland is crucial before any surgical intervention.

P10.23 Intraventricular pilocytic astrocytomas: Radiology, surgical management and outcome in a series of 8 patients

OBJECTIVE: Intraventricular pilocytic astrocytomas are a rare occurrence, accounting for approximately 4% -15.6% of all pilocytic astrocytomas.The aim of the study was to describe the radiology, surgical management and outcome in 8 patients with histopathologically proven intraventricular pilocytic astrocytoma (ivPA). Materials and methods: The study was conducted at the Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi. Between January 2010 and August 2015, 8 patients with histopathologically proven ivPA were identified. The radiological images were obtained from picture archiving and communication system (PACS). Clinical and surgical details were obtained from the computerized discharge summaries, and operative notes, whereas follow up was obtained from the patient record section. Results: There were 4 males and 4 females in the study. The mean age was 27.8 years (range 17-57). Headache with progressive loss of vision was the most common presentation. Duration of symptoms varied from 4 months to 2 years (mean 9.88 months). Except one patient, all patients with preoperative CT scan revealed calcifications in the lesion, with extensive calcification seen in 3 patients. All the tumors were predominantly hypointense on T1WI and iso to hyperintense on T2WI. Lesions in all patients showed heterogenous contrast enhancement on post gadolinium images. Mean blood loss in the series was 1969 ml (range 250 ml- 4500 ml).There was one death in this series due to meningitis and septic shock. Other complications included - disseminated intravascular coagulation (DIC), intraventricular hemorrhage, subdural hygroma, hemiplegia and hyponatremia. Preoperative diagnosis of iv PA could not be made on the basis of clinical and radiologic profile in any of thecases. CONCLUSION: Intraventricular pilocytic astrocytomas are rare tumors and are difficult to diagnose in the preoperative period based on the radiologic profile alone. These tumors can be extremely vascular with potential for massive blood loss. These tumors can be associated with extensive calcification and the calcified tumors have less bleeding as expected. Preoperative radiologic diagnosis by keeping a high index of suspicion can help in better operative planning, reducing blood loss and improving postoperative outcomes.

64 Magnetic resonance of the small bowel with early (70s) and late (7MINS) phase post gadolinium imaging to identify fibrosis in stricturing small bowel crohn’s disease

Background Strictures are a serious complication of Ileal Crohn’s disease (CD). Current assessment tools poorly differentiate fibrotic from inflammatory lesions and do not predict response. The magnetic resonance index of activity (MaRIA) is a validated means to assess activity. Its ability to characterise fibrosis remains unclear. Recent evidence suggests relative contrast enhancement (REC) of >24% on delayed MRI sequences may accurately detect fibrosis. Aim Compare MaRIA, RCE and biochemical activity in patients with Ileal CD. Method Prospective study of patients undergoing MRE for known CD. MRE was performed as standard with additional coronal T1 sequences 7 min post gadolinium administration. Two independent blinded Radiologists calculated RCE and MaRIA’s at 70 s and 7 min. Demographics and CRP were recorded. Results 26/29 MRE’s performed had ileal CD, median age=41 years, male=10 (38%). RCE >24% and high T2 signal intensity (SI); 6/26 (23%) and 11/26 (42.3%). REC >24% occurred in only 1/10 with a visible stenosis. Average MaRIA’s: 2/26 (7.7%) 11 severe. MaRIA’s did not change significantly between 70 s and 7 min. As expected T2 SI increased with MaRIA’s>11, 26 v 13 (p 11 (13.3 vs 5.2) and lower in patients with RCE >24% (3.9 vs 14), p Conclusions RCE may be a useful adjunct to current MRE and help detect fibrosis in small bowel lesions and warrants further investigation.

Development and Reliability of the OMERACT Thumb Base Osteoarthritis Magnetic Resonance Imaging Scoring System.

To develop the Outcome Measures in Rheumatology (OMERACT) thumb base osteoarthritis (OA) magnetic resonance imaging (MRI) scoring system (TOMS) for the assessment of inflammatory and structural abnormalities in this hand OA subset, and test its cross-sectional reliability. Included features and their scaling were agreed upon by members of the OMERACT MRI Task Force using the Hand OA MRI scoring system as a template. A reliability exercise was performed in which 3 readers participated, using a preliminary atlas with examples to facilitate reading. Each reader independently scored a set of 20 MRI (coronal and axial T1- and T2-weighted fat-suppressed images, of which 5 included T1-weighted fat-suppressed post-Gadolinium images). Intra- and inter-reader reliability were assessed using ICC, percentage exact agreement (PEA), and percentage close agreement (PCA). The TOMS assessed the first carpometacarpal (CMC-1) and scaphotrapeziotrapezoid (STT) joints for synovitis, subchondral bone defects (including erosions, cysts, and bone attrition), osteophytes, cartilage, and bone marrow lesions on a 0-3 scale (normal to severe). Subluxation was evaluated only in the CMC-1 joint (absent/present). Reliability of scoring for both joints was comparable. Interreader ICC were good for all features (0.77-0.99 and 0.74-0.96 for CMC-1 and STT joints, respectively). Intrareader reliability analyses gave similar results. PCA was ≥ 65% for all features. PEA was low to moderate, with better performance for subchondral bone defects, subluxation, and bone marrow lesions. A thumb base OA MRI scoring system has been developed. The OMERACT TOMS demonstrated good intrareader and interreader reliability. Longitudinal studies are warranted to investigate reliability of change scores and responsiveness.

Gadolinium Contrast Enhancement Improves Confidence in Diagnosing Recurrent Soft Tissue Sarcoma by MRI

To determine how utilization of postgadolinium magnetic resonance imaging (MRI) influenced reader accuracy and confidence at identifying postoperative soft tissue sarcoma (STS) recurrence among readers with various levels of expertise. This retrospective study was institutional review board approved and Health Insurance Portability and Accountability Act compliant. Postoperative MRI from 26 patients with prior STS resection (13 patients with confirmed recurrence, 13 without recurrence) was reviewed. Four blinded readers of varying expertise (radiology resident, fellow, attending, and orthopedic oncologist) initially evaluated only the precontrast images and rated each MRI for recurrence on a 5-point confidence scale. Assessment was repeated with the addition of contrast-enhanced sequences. Diagnostic accuracy based on confidence ratings was evaluated using the area under the receiver operating characteristic curve (AUC). Changes in confidence ratings were calculated using Wilcoxon signed-rank test. All readers demonstrated good diagnostic accuracy both with and without contrast-enhanced images (AUC >0.98 for each reader). When contrast-enhanced images were made available, the resident recorded improved confidence with both assigning (P = 0.031) and excluding recurrence (P = 0.006); the fellow showed improved confidence only with assigning recurrence (P = 0.015); and the surgeon showed improved confidence in excluding recurrence (P = 0.003). The addition of contrast-enhanced images did not significantly influence the diagnostic confidence of the attending radiologist. Diagnostic accuracy of MRI was excellent in evaluating postoperative STS recurrence, and reader confidence improved depending on expertise when postgadolinium imaging was included in the assessment.

Serial cardiac MRIs in adult Fontan patients detect progressive hepatic enlargement and congestion.

The progression of hepatic disease in adult Fontan patients is not well understood. They reviewed the experience with serial cardiac MRIs (CMR) in adult Fontan patients to determine if hepatic anatomic markers of prolonged Fontan exposure were present and if clinical predictors of progressive hepatic congestion could be identified. A retrospective cohort study of all adult Fontan patients who had undergone at least two CMRs was performed. Hepatic dimensions, inferior vena cava (IVC) size, right hepatic vein (RHV) size and spleen diameter were determined from images acquired at the time of clinically guided CMR. Two radiologists with expertise in hepatic imaging graded congestion and liver size independently using post-gadolinium contrast sequences. Twenty-seven patients met inclusion criteria. Over a mean time of 5.1 years between CMRs, there was a significant increase in mean lateral-medial hepatic dimension (P = .005), mean RHV diameter (P = .004), and mean splenic diameter (P = .001). Serial post-gadolinium imaging was available in 25/27 (93%) patients of which 15/27 (55%) showed evidence of progressive hepatic congestion across serial studies. Progressive hepatic congestion was associated with single ventricle ejection fraction (SVEF) less than 50% (P = .008), and larger indexed end-diastolic (EDVI) and end-systolic volume (ESVI). RHV diameter was the only anatomic variable significantly correlated with time from Fontan completion (P = .004). Serial CMRs detected progressive liver and hepatic vein enlargement in our cohort of adult Fontan patients over a mean time of 5.2 years. Progressive hepatic congestion occurs in a significant number of adult Fontan patients and may be associated with ventricular enlargement and decreased ventricular function by CMR.

Accuracy of Various MRI Sequences in Determining the Tumour Margin in Musculoskeletal Tumours.

SummaryBackgroundIt is imperative that bone tumour margin and extent of tumour involvement are accurately assessed pre-operatively in order for the surgeon to attain a safe surgical margin. In this study, we comprehensively assessed each of the findings that influence surgical planning, on various MRI sequences and compared them with the gold standard – pathology.Material/MethodsIn this prospective study including 21 patients with extremity bone tumours, margins as seen on various MRI sequences (T1, T2, STIR, DWI, post-gadolinium T1 FS) were measured and biopsies were obtained from each of these sites during the surgical resection. The resected tumour specimen and individual biopsy samples were studied to assess the true tumour margin. Margins on each of the MRI sequences were then compared with the gold standard – pathology. In addition to the intramedullary tumour margin, we also assessed the extent of soft tissue component, neurovascular bundle involvement, epiphyseal and joint involvement, and the presence or absence of skip lesions.ResultsT1-weighted imaging was the best sequence to measure tumour margin without resulting in clinically significant underestimation or overestimation of the tumour extent (mean difference of 0.8 mm; 95% confidence interval between −0.9 mm to 2.5 mm; inter-class correlation coefficient of 0.998). STIR and T1 FS post-gadolinium imaging grossly overestimated tumour extent by an average of 16.7 mm and 16.8 mm, respectively (P values <0.05). Post-gadolinium imaging was better to assess joint involvement while T1 and STIR were the best to assess epiphyseal involvement.ConclusionsT1-weighted imaging was the best sequence to assess longitudinal intramedullary tumour extent. We suggest that osteotomy plane 1.5 cm beyond the T1 tumour margin is safe and also limits unwarranted surgical bone loss. However, this needs to be prospectively proven with a larger sample size.

Incidental ferumoxytol artifacts in clinical brain MR imaging

Ferumoxytol (Feraheme) is a parenteral therapy approved for treatment of iron deficiency anemia. The product insert for ferumoxytol states that it may affect the diagnostic ability of MRI for up to 3months. However, the expected effects may not be commonly recognized among clinical neuroradiologists. Our purpose is to describe the artifacts we have seen at our institution during routine clinical practice. We reviewed the patients at our institution that had brain MRI performed within 90days of receiving intravenous ferumoxytol. The imaging was reviewed for specific findings, including diffusion-weighted imaging vascular susceptibility artifact, gradient-echo echo-planar T2*-weighted vascular susceptibility artifact, SWI/SWAN vascular susceptibility artifact, hypointense vascular signal on T2-weighted images, pre-gadolinium contrast vascular enhancement on magnetization-prepared rapid acquisition gradient echo (MPRAGE) imaging, and effects on post-gadolinium contrast T1 imaging. Multiple artifacts were observed in patients having a brain MRI within 3days of receiving intravenous ferumoxytol. These included susceptibility artifact on DWI, GRE, and SWAN/SWI imaging, pre-gadolinium contrast increased vascular signal on MPRAGE imaging, and decreased expected enhancement on post-gadolinium contrast T1-weighted imaging. Ferumoxytol can create imaging artifacts which complicate clinical interpretation when brain MRI is performed within 3days of administration. Recognition of the constellation of artifacts produced by ferumoxytol is important in order to obviate additional unnecessary examinations and mitigate errors in interpretation.

Pituitary stalk thickening: the role of an innovative MRI imaging analysis which may assist in determining clinical management.

Disease processes that affect the pituitary stalk are broad; the diagnosis and management of these lesions remains unclear. The aim was to assess the clinical, biochemical and histopathological characteristics of pituitary stalk lesions and their association with specific MRI features in order to provide diagnostic and prognostic guidance. Retrospective observational study of 36 patients (mean age 37years, range: 4-83) with pituitary stalk thickening evaluated at a university hospital in Oxford, UK, 2007-2015. We reviewed morphology, signal intensity, enhancement and texture appearance at MRI (evaluated with the ImageJ programme), along with clinical, biochemical, histopathological and long-term follow-up data. Diagnosis was considered certain for 22 patients: 46% neoplastic, 32% inflammatory and 22% congenital lesions. In the remaining 14 patients, a diagnosis of a non-neoplastic disorder was assumed on the basis of long-term follow-up (mean 41.3months, range: 12-84). Diabetes insipidus and headache were common features in 47 and 42% at presentation, with secondary hypogonadism the most frequent anterior pituitary defect. Neoplasia was suggested on size criteria or progression with 30% sensitivity. However, textural analysis of MRI scans revealed a significant correlation between the tumour pathology and pituitary stalk heterogeneity in pre- and post-gadolinium T1-weighted images (sensitivity: 88.9%, specificity: 91.7%). New techniques of MRI imaging analysis may identify clinically significant neoplastic lesions, thus directing future therapy. We propose possible textural heterogeneity criteria of the pituitary stalk on pre- and post-gadolinium T1 images with the aim of differentiating between neoplastic and non-neoplastic lesions with a high degree of accuracy.

The many shades of enhancement: timing of post-gadolinium images strongly influences the scoring of juvenile idiopathic arthritis wrist involvement on MRI.

Potential long-term side effects of treatment for juvenile idiopathic arthritis are concerning. This has necessitated accurate tools, such as MRI, to monitor treatment response and allow for personalized therapy. To examine the extent to which timing of post-contrast MR images influences the scoring of inflammatory change in the wrist in children with juvenile idiopathic arthritis. We studied two sets of post-contrast 3-D gradient echo MRI series of the wrist in 34 children with juvenile idiopathic arthritis. These images were obtained immediately after administration of intravenous contrast material and again after approximately 10min. The dataset was drawn from a prospective multicenter project conducted 2006-2010. We assessed five wrist locations for synovial enhancement, effusion and overall inflammation. Examinations were scored by one radiologist in two sessions - the first was based on the early post-contrast images, and the later session, for which the previous findings were masked, was based on the later post-contrast images. Fifty-two of the 170 locations (30.6%) received a higher synovial enhancement score based on the late post-contrast images as compared to the early images. Sixty of the 170 (35%) locations received a higher total inflammation score. The mean scores of synovial enhancement and total inflammation were significantly higher when based on the late post-contrast images as compared to the early post-contrast images. An MRI-based scoring system for the presence and degree of synovitis should be based on a standardized MR-protocol with a fixed interval between intravenous contrast injection and post-contrast images.

MAGNETIC RESONANCE IMAGING OF INTRACRANIAL INFLAMMATORY CONDITIONS IN DOGS: SENSITIVITY OF SUBTRACTION IMAGES VERSUS PRE- AND POST-GADOLINIUM T1-WEIGHTED IMAGE PAIRS.

Ante mortem diagnosis of canine meningoencephalitis is usually based on the results of neurologic examination, cerebrospinal fluid analysis and magnetic resonance (MR) imaging. It has been hypothesized that subtraction MR imaging may increase the sensitivity of MR for intracranial inflammatory lesions compared to conventional post-gadolinium T1-weighted imaging. Sensitivity of pre- and post-gadolinium (C-/C+) image pairs and dynamic subtraction (DS) images was compared in a retrospective diagnostic accuracy study of 52 dogs with inflammatory cerebrospinal fluid and 67 dogs with idiopathic epilepsy. Series of transverse C-/C+ and DS images were reviewed independently for signs of abnormal enhancement affecting the pachymeninges, leptomeninges or intra-axial structures. Sensitivity of C-/C+ image pairs and DS images was 48% (95% CI: 35-61%) and 65% (95% CI: 52-77%), respectively (P = 0.01). Intra-axial lesions were observed more frequently than meningeal lesions in both C-/C+ (43% vs. 31%) and DS images (61% vs. 22%). The difference in sensitivities of C-/C+ and DS series was entirely due to increased sensitivity of DS images for intra-axial lesions. Eight (12%) dogs with epilepsy had evidence of intra-axial gadolinium accumulation affecting the cerebral cortex in DS images. This finding may represent a false-positive result or a true sign of pathology, possibly associated with a leaky blood-brain barrier in areas of the brain affected by neovascularization secondary to repeated seizures. Results suggest that DS imaging has higher sensitivity than comparison of pre- and post-gadolinium image pairs for inflammatory intra-axial lesions.

Neurenteric cyst presented with progressive head and neck pain

A 37-year-old female patient was admitted to the neurology department of a hospital because of headache. Neurologic examination of the patient was normal. Magnetic resonance imaging of the craniocervical junction region revealed a well-defined extra-axial cystic lesion measuring 1.0×0.6×1.3 cm located ventral from the medulla to the C1 vertebra without cord compression. T1-, T2-, and post-gadolinium T1-weighted images showed a homogeneously hyperintense cyst (Fig. 1) without enhancement. The patient was diagnosed with neurenteric cyst. She was followed up as an outpatient. One year later, she visited the hospital because of neck pain. Because we observed cord compression at the C1 and C2 levels on control magnetic resonance imaging (Fig. 2), the patient underwent total excision of the lesion and the histopathologic diagnosis was neurenteric cyst.

What predicts early volumetric edema increase following stereotactic radiosurgery for brain metastases?

A volumetric analysis of pre- and post-radiosurgery (PreSRS and PostSRS) edema in patients with cerebral metastases was performed to determine factors of a predictive model assessing the risk of developing increased edema relatively early after SRS. One-hundred-fourteen metastases in 55 patients were analyzed. Selection for this analysis required an MRI ≤ 30 days before SRS and an MRI ≤ 100 days after SRS. Tumor volumes were calculated on PreSRS, SRS, and PostSRS T1-weighted postgadolinium images while edema volumes were calculating using PreSRS and PostSRS fluid-attenuated inversion recovery MR images. An increase in edema was defined as an increase in measurable edema of at least 5%. We developed and evaluated a model predicting the relative risk (RR) of increased edema after SRS. Peritumoral edema increased in 18% (21/114) of the analyzed lesions. Melanoma/renal histology, recursive partitioning analysis class III, and prior WBRT carried RRs of developing postSRS edema increase of 2.45, 2.48, and 3.16, respectively (all P values <0.05). The PreSRS edema/tumor ratio predicted for a RR of 1.007/ratio unit, and steroid dose at time of SRS predicted for a RR of 0.89/mg (all P values <0.05). A predictive model for assessing the RR of increased edema after SRS was developed based from these data and may be useful in identifying patients who might benefit from prophylactic anti-edema therapies before, during, or after SRS. This model could be used as the basis of inclusion criteria for prospective trials investigating novel anti-edema therapies.

Diagnostic accuracy of diffusion-weighted MR imaging versus delayed gadolinium enhanced T1-weighted imaging in middle ear recurrent cholesteatoma: A retrospective study of 39 patients

MR imaging using diffusion-weighted (DW) images and delayed gadolinium-enhanced T1-weighted images is evolving into an alternative to second look surgery in detection of recurrent cholesteatomas. The aim of this study was to retrospectively compare the DW images, the post-gadolinium T1-weighted images and the combination of both methods in this indication. We retrospectively evaluated the MR examination of 39 patients clinically suspected for a recurrent cholesteatoma. Patients in the study underwent DW sequences, delayed gadolinium enhanced T1-weighted sequences as well as standard uninjected protocol using T1 and T2 sequences. Three blinded radiologists evaluated three data sets: a set of post-gadolinium T1-weighted images, a set of DW images and a set of the combination of both methods. The interobserver agreement was evaluated and the diagnostic accuracy of each method was described by sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The performances of the three techniques were also evaluated using ROC curves, from which the AUC were compared. Results were compared with surgical results or a two-year follow-up. The overall sensitivity and specificity were respectively 63% and 71% for the post-gadolinium T1-weighted images, 88% and 75% for the DW images and 84% and 75% for the combined images. The PPV and NPV were respectively 89% and 33% for the post-gadolinium T1-weighted images, 93% and 62% for the DW images and 93% and 55% for the combined images. The sensitivity and the NPV were significantly different between the three methods (P<0.0001 and P=0.027). There was no statistically significant difference in specificity or PPV between the three methods (P=0.931 and P=0.650). The diagnostic accuracy evaluated with the AUC showed no statistically significant difference between the DW images and the combined images (P=0.433). MR imaging reliably identifies those patients suspected for recurrent cholesteatoma who require a surgical second look by using DW MR imaging. The combination with delayed gadolinium enhanced T1-weighted sequences does not significantly increase the diagnostic accuracy of the examination.

RTRB-23SENSITIVITY ANALYSIS OF PERMITTIVITY AND CONDUCTIVITY ON ALTERNATING ELECTRIC FIELDS THERAPY FOR RECURRENT GLIOBLASTOMA

BACKGROUND: The NovoTTF Therapy device uses two pairs of arrays to deliver frequency-tuned alternating electric fields at 200 kHz to treat recurrent glioblastoma. Although its efficacy is equivalent to chemotherapies, the precise distribution of the electric fields within the brain remains poorly understood. METHODS: We performed computerized simulation to determine the electric field distribution inside a patient's brain with a right parietal recurrent glioblastoma, using co-registered post-gadolinium T1-weighted, T2 and MP RAGE MRI images together with pre-specified relative permittivity and conductivity values for each of the cerebral structures. RESULTS: We found higher field strength at the scalp surface, ventricular horns and the medial surface of the tumor. Because the mass density and charges may vary among tumors, particularly when there is variation on the cystic make-up of the necrotic tumor, we performed a sensitivity analysis to investigate the relative contribution of permittivity and conductivity parameters to changes in the electric field distribution. Within the solid portion of the gross tumor volume (GTV), we found no variation in electric field strength from changes in permittivity from 0.001-10,000, mean electric field strength from 81.156 to 78.854 V/m, but marked variation from changes in conductivity from 0.001-100 S/m, mean electric field strength from 131.22 to 1.1463 V/cm. Within the necrotic core of the GTV, we also found no variation in electric field strength from changes in permittivity from 0.001-10,000, mean electric field strength from 39.456 to 40.180 V/m, but again marked variation from changes in conductivity from 0.001-100 S/m, mean electric field strength from 43.074 to 7.2933 V/cm. CONCLUSIONS: The results indicate that conductivity of the tumor plays a greater role than permittivity in the electric field distribution from NovoTTF Therapy.

Magnetic resonance imaging findings of paracoccidioidomycosis in the musculoskeletal system.

To describe magnetic resonance imaging (MRI) findings in musculoskeletal paracoccidioidomycosis (PCM). Retrospective case series study after IRB approval. Two musculoskeletal radiologists reviewed in consensus the MRI findings of 11 patients with microbiologically and/or pathologically proven osteoarticular PCM. The MRI evaluation included discrimination of abnormalities in joints, bones and soft tissues. Mean age of patients was 29years (10-55years), eight men and three women. Musculoskeletal involvement was the only or the primary presentation of the disease in seven patients (63%). Osteomyelitis was the most common presentation, with seven cases (63%). Primary arthritis was found in one patient (9%). Isolated extra-articular soft tissue PCM was found in three patients: myositis (2) and subcutaneous infection (1). All cases showed regions with signal intensity higher than or similar to the signal of muscle on T1-weighted images. Penumbra sign was present in five cases (45%). T2-weighted images showed reactive soft tissue oedema in eight cases (72%). Post-gadolinium images showed peripheral (8/9) or heterogeneous (1/9) enhancement. Synovial enhancement was present in all cases of joint involvement (6/6). Lipomatosis arborescens was documented in one case of chronic knee involvement. To our knowledge, this is the first case series describing MRI findings of musculoskeletal PCM. Musculoskeletal involvement was the primary presentation of the disease in most cases, and therefore, neoplasms were initially in the differential diagnosis. Osteomyelitis was the most common presentation, often with secondary involvement of joint and or soft tissue.

A longitudinally extensive myelopathy in a patient with AIDS

A 42-year-old right-handed African–American woman had been diagnosed with AIDS 11 years before the abrupt onset of numbness and heaviness in her left lower limb. On presentation, her absolute CD4...

Detection of inflammatory sacroiliitis in children with magnetic resonance imaging: is gadolinium contrast enhancement necessary?

In adults, gadolinium contrast enhancement does not add incremental value to fluid-sensitive sequences for evaluation of bone marrow edema. This study was undertaken to determine if magnetic resonance imaging (MRI) contrast is necessary to assess lesions consistent with inflammatory sacroiliitis in children. Patients with clinically suspected or diagnosed juvenile spondyloarthritis (SpA) underwent pelvic MRI consisting of multiplanar fluid-sensitive and postgadolinium T1-weighted fat-saturated sequences including dedicated sacral imaging. Three radiologists independently evaluated the fluid-sensitive sequences, and later, the complete study (including postcontrast images). With postcontrast imaging as the reference standard, we calculated the test properties of fluid-sensitive sequences for depiction of acute and chronic findings consistent with sacroiliitis. The 51 patients had a median age of 15 years, and 57% were male. Nineteen patients (22 joints) were diagnosed as having sacroiliitis based on postcontrast imaging, and none had synovitis in the absence of bone marrow edema. All 22 joints demonstrated bone marrow edema on both fluid-sensitive and postgadolinium T1-weighted fat-saturated sequences. Eighteen percent of joints with sacroiliitis had capsulitis, which was observed on both noncontrast and postcontrast imaging. Fifty-nine percent of joints with sacroiliitis had synovitis on postcontrast imaging. Sensitivity, specificity, positive predictive value, and negative predictive value of fluid-sensitive sequences for the detection of acute inflammatory lesions consistent with sacroiliitis using postgadolinium imaging as the reference standard were excellent. Interrater reliability was substantial for all parameters. Our findings indicate that fluid-sensitive sequences are sufficient to detect acute and chronic lesions consistent with inflammatory sacroiliitis in children.