High Sensitivity Of Magnetic Resonance Imaging Research Articles

Is non-contrast-enhanced magnetic resonance imaging cost-effective for screening of hepatocellular carcinoma?

Ultrasonography (US) is the current standard of care for imaging surveillance in patients at risk of hepatocellular carcinoma (HCC). Magnetic resonance imaging (MRI) has been explored as an alternative, given the higher sensitivity of MRI, although this comes at a higher cost. We performed a cost-effective analysis comparing US and dual-sequence non-contrast-enhanced MRI (NCEMRI) for HCC surveillance in the local setting. Cost-effectiveness analysis of no surveillance, US surveillance and NCEMRI surveillance was performed using Markov modelling and microsimulation. At-risk patient cohort was simulated and followed up for 40 years to estimate the patients' disease status, direct medical costs and effectiveness. Quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio were calculated. Exactly 482,000 patients with an average age of 40 years were simulated and followed up for 40 years. The average total costs and QALYs for the three scenarios - no surveillance, US surveillance and NCEMRI surveillance - were SGD 1,193/7.460 QALYs, SGD 8,099/11.195 QALYs and SGD 9,720/11.366 QALYs, respectively. Despite NCEMRI having a superior diagnostic accuracy, it is a less cost-effective strategy than US for HCC surveillance in the general at-risk population. Future local cost-effectiveness analyses should include stratifying surveillance methods with a variety of imaging techniques (US, NCEMRI, contrast-enhanced MRI) based on patients' risk profiles.

The role of magnetic resonance imaging in the diagnosis of malignant bone neoplasms. Current state of an issue

The review article is about clinical experience in the use of modern tomographic methods (magnetic resonance imaging (MRI) and X-ray computed tomography (CT)) in the diagnosis and assessment of the progression of malignant bone neoplasms, summarizing the results of the largest studies demonstrating the comparative characteristics of the methods. Numerous data demonstrate high sensitivity of MRI and form the following diagnostic tasks that can be solved by this method: the involvement degree of soft tissues in the pathological process, damage to the neurovascular bundle, the articular surface, assessment of the extent of tumor in the bone marrow canal. At the same time, CT shows a higher sensitivity in assessing cortical destruction and the degree of matrix mineralization. The article discusses the variety of program sequences and modes of MRI scanning, the prospects of the method in assessing the prevalence, staging, and differential diagnosis of bone tumors.

Do musculoskeletal ultrasound and magnetic resonance imaging identify synovitis and tenosynovitis at the same joints and tendons? A comparative study in early inflammatory arthritis and clinically suspect arthralgia

ObjectiveUltrasound (US) and magnetic resonance imaging (MRI) are recommended in the diagnostic process of rheumatoid arthritis. Research on its comparability in early disease phases is scarce. Therefore, we compared synovitis and tenosynovitis detected by US and MRI on joint/tendon level.MethodsEight hundred forty joints and 700 tendons of 70 consecutive patients, presenting with inflammatory arthritis or clinically suspect arthralgia, underwent US and MRI of MCP (2–5), wrist and MTP (1–5) joints at the same day. Greyscale (GS) and power Doppler (PD) synovitis were scored according to the modified Szkudlarek method (combining synovial effusion and hypertrophy) and the recently published EULAR-OMERACT method (synovial hypertrophy regardless of the presence of effusion) on static images. US-detected tenosynovitis was scored according to the OMERACT. MRI scans were scored according to the RAMRIS. Test characteristics were calculated on joint/tendon level with MRI as reference. Cut-off for US scores were ≥ 1 and ≥ 2 and for MRI ≥ 1.ResultsCompared to MRI, GS synovitis according to EULAR-OMERACT (cut-off ≥ 1) had a sensitivity ranging from 29 to 75% for the different joint locations; specificity ranged from 80 to 98%. For the modified Szkudlarek method, the sensitivity was 68–91% and specificity 52–71%. PD synovitis had a sensitivity of 30–54% and specificity 97–99% compared to MRI. The sensitivity to detect GS tenosynovitis was 50–78% and the specificity 80–94%. For PD tenosynovitis, the sensitivity was 19–58% and specificity 98–100%.ConclusionCurrent data showed that US is less sensitive than MRI in the early detection of synovitis and tenosynovitis, but resulted in only few non-specific findings. The higher sensitivity of MRI is at the expense of less accessibility and higher costs.

Synthesis and in vitro experiments of carcinoma vascular endothelial targeting polymeric nano-micelles combining small particle size and supermagnetic sensitivity

Objective: To construct carcinoma vascular endothelial-targeted polymeric nanomicelles with high magnetic resonance imaging (MRI) sensitivity and to evaluate their biological safety and in vitro tumor-targeting effect, and to monitor their feasibility using clinical MRI scanner.Method: Amphiphilic block copolymer, poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL) was synthesized via the ring-opening polymerization of ε-caprolactone (CL) initiated by poly(ethylene glycol) (PEG), in which cyclic pentapeptide Arg-Gly-Asp (cRGD) was conjugated with the terminal of hydrophilic PEG block. During the self-assembly of PEG-PCL micelles, superparamagnetic γ-Fe2O3 nanoparticles (11 nm) was loaded into the hydrophobic core. The cRGD-terminated γ-Fe2O3-loaded polymeric micelles targeting to carcinoma vascular endothelial cells, were characterized in particle size, morphology, loading efficiency and so on, especially high MRI sensitivity in vitro. Normal hepatic vascular endothelial cells (ED25) were incubated with the resulting micelles for assessing their safety. Human hepatic carcinoma vascular endothelial cells (T3A) were cultured with the resulting micelles to assess the micelle uptake using Prussian blue staining and the cell signal intensity using MRI.Results: All the polymeric micelles exhibited ultra-small particle sizes with approximately 50 nm, high relaxation rate, and low toxicity even at high iron concentrations. More blue-stained iron particles were present in the targeting group than the non-targeting and competitive inhibition groups. In vitro MRI showed T2WI and T2 relaxation times were significantly lower in the targeting group than in the other two groups.Conclusion: γ-Fe2O3-loaded PEG-PCL micelles not only possess ultra-small size and high superparamagnetic sensitivity, also can be actively targeted to carcinoma vascular endothelial cells by tumor-targeted cRGD. It appears to be a promising contrast agent for tumor-targeted imaging.

3D anatomical and perfusion MRI for longitudinal evaluation of biomaterials for bone regeneration of femoral bone defect in rats

Magnetic Resonance Imaging (MRI) appears as a good surrogate to Computed Tomography (CT) scan as it does not involve radiation. In this context, a 3D anatomical and perfusion MR imaging protocol was developed to follow the evolution of bone regeneration and the neo-vascularization in femoral bone defects in rats. For this, three different biomaterials based on Pullulan-Dextran and containing either Fucoidan or HydroxyApatite or both were implanted. In vivo MRI, ex vivo micro-CT and histology were performed 1, 3 and 5 weeks after implantation. The high spatially resolved (156 × 182 × 195 µm) anatomical images showed a high contrast from the defects filled with biomaterials that decreased over time due to bone formation. The 3D Dynamic Contrast Enhanced (DCE) imaging with high temporal resolution (1 image/19 s) enabled to detect a modification in the Area-Under-The-Gadolinium-Curve over the weeks post implantation. The high sensitivity of MRI enabled to distinguish which biomaterial was the least efficient for bone regeneration, which was confirmed by micro-CT images and by a lower vessel density observed by histology. In conclusion, the methodology developed here highlights the efficiency of longitudinal MRI for tissue engineering as a routine small animal exam.

MAGNETIC RESONANCE IMAGING OF THE HEART IN DIAGNOSTICS OF VARIOUS TYPES OF MYOCARDITIS

Aim. To study the radiation semiotics of various clinical and morphological types of myocarditis with magnetic resonance imaging (MRI). Material and methods. Totally, 70 patients included, with suspected by clinical and lab data myocarditis (28 females, 42 males; mean age 37,0±13,1 y.o). All patients underwent endomyocardial biopsy (EMB) and MRI with intravenous contrasting. Sensitivity of MRI method was evaluated with relation to EMB. Exclusion criteria had been the comorbid ischemic heart disease. Results. Among 70 patients with histologically verified myocarditis, only 47 had this diagnosis by MRI data, sensitivity was set as 67%. In acute active and acute borderline myocardities there is high sensitivity of MRI — 86%; in chronic active myocarditis — 74%, in patients with chronic borderline myocarditis — 55%. Three MRI-criteria of myocarditis were found in acute active myocarditis. Acute borderline myocarditis in most cases presented with 2 signs: edema and delayed contrast enhancement. Significant difference of active myocarditis from other clinical and morphological types is dominance of transmural pattern of delayed contrasting. Also, there is interdependence of inflammation activity by EMB and severity of myocardium edema (64,3% vs. 40,5%, p=0,005). The main differentiating factor of chronic myocarditis is collecting kind of the delayed contrasting areas, which spread more than the zone of myocardium edema. Conclusion. Magnetic resonance imaging shows the highest sensitivity in revealing of acute myocarditis, and in cases of chronic myocarditis the sensitivity depends on activity of inflammation. The overlap of the areas of delayed contrasting and myocardial edema make it to differentiate acute and chronic process in myocardium. Dignostics of chronic borderline myocarditis is impossible unless EMB is done.

Subdividing BI-RADS category 4 breast lesions observed on magnetic resonance imaging: Is it feasible?

Radiol Bras. 2016 Mai/Jun;49(3):V In clinical practice, there are various purposes for which magnetic resonance imaging (MRI) of the breasts is indicated, from the screening of high-risk patients to the staging and treatment planning for patients with breast cancer. This method has better sensitivity than conventional imaging (mammography and ultrasound) for the diagnosis of malignant breast lesions and has greater accuracy in evaluating the size and morphological features of tumors, as well as in detecting multifocal and multicentric lesions. However, despite the high sensitivity of MRI, many studies have reported that its specificity is low and that it produces a large number of false positives, which can lead to unnecessary biopsies and surgical procedures. The Breast Imaging Reporting and Data System (BI-RADS), developed by the American College of Radiology and continually updated since 1992, is a guide with recommendations for the standardization of breast imaging (mammography, ultrasound, and MRI) reports and for the auditing of centers employing such methods. Its objective is to standardize the nomenclature used in the reports, which should have a diagnostic conclusion and should propose management, according to the probability of malignancy. However, the cases classified as suspicious (BI-RADS category 4) show wide variation in the risk of malignancy (2–95%), which led to the subdivision of this category, as follows: 4A (low suspicion, risk of 2–10%); 4B (intermediate suspicion, risk of 11–50%); and 4C (high suspicion, risk of 51–95%). In the most recent editions of the BI-RADS, this subdivision was incorporated into the lexicon of mammography and ultrasound, although it has yet to be incorporated into that of MRI, because there is a lack of published studies to support such assessment. Published in this issue of Radiologia Brasileira, the article “Predictive performance of BI-RADS magnetic resonance imaging descriptors in the context of suspicious (category 4) findings” is one of the first in the literature to assess the likelihood of malignancy related to MRI findings in lesions classified as BI-RADS category 4. In that study, Almeida et al. present consistent methodology and statistical analysis, emphasizing the credibility of their findings. This type of study is essential to defining the criteria to be used for the subdivision of suspicious findings into the categories

Toward an In Vivo Neuroimaging Template of Human Brainstem Nuclei of the Ascending Arousal, Autonomic, and Motor Systems.

Brainstem nuclei (Bn) in humans play a crucial role in vital functions, such as arousal, autonomic homeostasis, sensory and motor relay, nociception, sleep, and cranial nerve function, and they have been implicated in a vast array of brain pathologies. However, an in vivo delineation of most human Bn has been elusive because of limited sensitivity and contrast for detecting these small regions using standard neuroimaging methods. To precisely identify several human Bn in vivo, we employed a 7 Tesla scanner equipped with multi-channel receive-coil array, which provided high magnetic resonance imaging sensitivity, and a multi-contrast (diffusion fractional anisotropy and T2-weighted) echo-planar-imaging approach, which provided complementary contrasts for Bn anatomy with matched geometric distortions and resolution. Through a combined examination of 1.3 mm(3) multi-contrast anatomical images acquired in healthy human adults, we semi-automatically generated in vivo probabilistic Bn labels of the ascending arousal (median and dorsal raphe), autonomic (raphe magnus, periaqueductal gray), and motor (inferior olivary nuclei, two subregions of the substantia nigra compatible with pars compacta and pars reticulata, two subregions of the red nucleus, and, in the diencephalon, two subregions of the subthalamic nucleus) systems. These labels constitute a first step toward the development of an in vivo neuroimaging template of Bn in standard space to facilitate future clinical and research investigations of human brainstem function and pathology. Proof-of-concept clinical use of this template is demonstrated in a minimally conscious patient with traumatic brainstem hemorrhages precisely localized to the raphe Bn involved in arousal.

Hybrid Fe3O4-Poly(acrylic acid) Nanogels for Theranostic Cancer Treatment.

Multifunctional nanomedicine integrated with both therapy and diagnostics holds vast potential in cancer treatment. We developed hybrid Fe3O4-poly(acrylic acid) (PAA) nanogels for both drug delivery and magnetic resonance imaging (MRI). Superparamagnetic Fe3O4 nanoparticles were encapsulated inside porous PAA nanogels via an in situ co-precipitation approach. With successive growth of magnetic nanoparticles, the highest magnetization saturation (M(s)) value of the Fe3O4 nanoparticles in the PAA nanogels was determined as 20 emu/g. The resulting hybrid Fe3O4-PAA nanogels showed high drug loading capacity (98%) and sustained drug release in vitro. Cytotoxicity assays and cellular imaging demonstrated that the hybrid nanogels were highly biocompatible and efficiently internalized in human neuroblastoma SH-SY5Y cells. In MRI studies, the hybrid nanogels exhibited an excellent contrast in T2 weighted imaging and a high MRI sensitivity in the tumor site.

Efficacy of MRI visible iron oxide nanoparticles in delivering minicircle DNA into liver via intrabiliary infusion

Gene therapy is a very promising technology for treatment of liver diseases. Minicircle DNA (MCDNA) is a versatile gene vector, which possesses excellent features in bio-safety and duration of transgene expression. However, its application has been hampered by the lack of an efficient gene delivery system. In this study, we developed a magnetic resonance imaging (MRI) visible nanoparticle to monitor MCDNA gene delivery and explore the potential of gene therapy in vivo. The nanoparticle was constructed via self-assembly of stearic acid modified low molecular polyethyleneimine (stPEI) and superparamagnetic iron oxide (SPIO) nanocrystals. The multiple SPIO nanocrystals with a controlled clustering structure in the nanoparticles were designed to achieve high MRI sensitivity. Furthermore, the MCDNA was combined with the nanoparticles via electronic interaction. Through intrabiliary infusion, the stPEI-SPIO/MCDNA nanoparticles were efficiently delivered to liver that was visualized by MRI in vivo and confirmed by histology. Moreover, the MCDNA nanoparticles exhibited non-cytotoxicity with no obvious inflammation in the transfection sites. These results indicate that stPEI-SPIO nanoparticle is able to serve as both an efficient DNA vector delivery system and a sensitive agent for MRI visualization.

Abstract P3-02-11: Screening Magnetic Resonance Imaging (MRI) of the breast in women at increased lifetime risk for breast cancer: A retrospective single institution study.

Abstract Background: Multiple factors are associated with an increased lifetime risk of breast cancer, including inheritance of an abnormal BRCA 1/2 gene, history of lobular carcinoma in situ (LCIS) or atypical hyperplasia, family history of breast cancer or previous chest wall radiation. In 2007, the American Cancer Society released updated guidelines for breast cancer screening based on risk stratification. These guidelines added annual MRI screening to mammography for women with greater than or equal to a 20–25% lifetime risk. Breast MRI screening trials have consistently demonstrated a higher sensitivity of MRI for malignancy compared with mammography, with an additional cancer yield from MRI of approximately 3%. The purpose of this study was to evaluate MRI screening outcomes in women with an increased risk for breast cancer evaluated in an established breast subspecialty clinic within the University of Wisconsin (UW) Hospital and Clinics. Methods: Patients (Pts) were included if they were seen by a UW breast center nurse practitioner, medical or surgical oncologist between 1/1/2007–3/1/2011 with a diagnosis code of: family history of breast or ovarian cancer, genetic susceptibility to malignant neoplasm or genetic carrier, Hodgkin's disease, LCIS, or atypical hyperplasia. Pts with a co-existing diagnosis of invasive breast cancer or ductal carcinoma in situ prior to initial encounter were excluded. Demographic information, breast cancer risk factors, estimated lifetime risk of breast cancer and screening recommendations were abstracted from the medical record. Results of subsequent breast imaging examinations (including breast MRI, diagnostic and screening mammography, and image-guided biopsies) were analyzed with the use of the mammography information system (PenRad™). Results: Of 276 women who met the inclusion criteria, 148 underwent at least 1 screening breast MRI. The majority of MRI screened pts were premenopausal (82%) and Caucasian (96.6%) with a mean age of 42.5 (range 20–68) at their initial encounter. Eighty five percent had a first degree relative with breast cancer and 72.3% of pts undergoing MRI screening had a documented lifetime risk of breast cancer of 20% or greater using a validated model. Within this MRI-screened cohort, 18.2% had a known genetic predisposition to breast cancer. Over the time assessed, 307 MRIs were performed in the 148 pts. Biopsy was recommended and performed based on the results of the MRI in 31 of 307 exams (10%). Ten cancers were detected for a positive predictive value based on biopsy performed of 32% and an overall cancer yield of 3.3% (10 of 307 MRI exams). All cancers were stage 0 - II. All pts are currently with no evidence of disease. Conclusion: Breast MRI has a high positive predictive value and cancer yield with an acceptable biopsy rate in a diverse group of high risk women undergoing breast MRI at an academic center outside of a clinical trial. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-02-11.

Highlights of This Issue

Although changes in mitochondrial DNA (mtDNA) copy number have been implicated in different cancers, specific data on mtDNA copy number and colorectal cancer risk have been lacking. To address this lack of data, Thyagarajan and colleagues evaluated the association between mtDNA copy number and colorectal cancer risk among participants in the Singapore Chinese Health Study. The authors report that Individuals with low and high relative mtDNA copy numbers both showed increased risk of colorectal cancer, suggesting that mtDNA may play a critical role in colorectal cancer development.BRCA1/2 mutation carriers are recommended to undergo breast cancer screening with magnetic resonance imaging (MRI) because of the high sensitivity of MRI. To evaluate the impact of various screening protocols on cancer detection and mortality, Heijnsdijk and colleagues analyzed 3 studies of BRCA1/2 mutation carriers who were undergoing the recommended annual MRI and mammography screenings. The model from this analysis predicts breast cancer mortality reductions of 42% to 47% for mammography screening, 48% to 61% for MRI screening, and 50% to 62% for combined screening. These studies suggest substantial mortality benefits with the use of MRI to screen BRCA1/2 mutation carriers.To test cell-cycle proteins as predictive markers in urothelial carcinoma, Lenz and colleagues assembled tissue from 491 bladder cancer cases as tissue microarrays and examined them for aberrant expression of p53, p63, p16, cyclin D1, Rb, and Ki-67. The authors report that overexpression of p53 and Ki-67 was associated with high-grade tumors, whereas expression of p63 and p16 was decreased in high-grade tumors. These results reveal significant heterogeneity in the expression of key cell-cycle proteins in bladder cancer tissue.To identify novel gene variants for breast cancer risk, Higginbotham and colleagues conducted a multistage genetic association study in a series of breast cancer study populations. In their analysis, over 1,100 single-nucleotide polymorphisms were examined for evidence of association with breast cancer in independent study groups. The authors found that a series of validated breast cancer risk variants yielded the expected associations. In addition, 2 previously unreported loci were significantly associated with breast cancer risk in 3 of the 4 study populations. This important report adds to the compendium of known breast cancer genetic risk variants.

MR imaging of acute cervical spinal ligamentous and soft tissue trauma

The increasing availability of magnetic resonance imaging (MRI) and the high sensitivity of MRI for soft tissue injury are resulting in the increased use of MRI for the evaluation of acute trauma. As cervical spine injury can have a devastating consequence, MRI is being more commonly used to evaluate cervical spine injury in the acute setting, necessitating emergent interpretation by the on-call radiologist. Unless one is formally trained in a trauma center, the MRI findings of soft tissue and ligamentous cervical spine injury may not be fully appreciated. The goal of this pictorial review is to familiarize the reader with some of the more common soft tissue, vascular, and ligamentous injuries seen on MRI of the cervical spine in the emergent setting.

Folate-targeted polymeric micelles loaded with ultrasmall superparamagnetic iron oxide: combined small size and high MRI sensitivity.

Targeted delivery of contrast agents is a highly desirable strategy for enhancing diagnostic efficiency and reducing side effects and toxicity. Water-soluble and tumor-targeting superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by loading hydrophobic SPIONs into micelles assembled from an amphiphilic block copolymer poly(ethylene glycol)- poly(ɛ-caprolactone) (PEG-PCL) bearing folate in the distal ends of PEG chains. Compared to the water-soluble SPIONs obtained by small molecular surfactant coating, ultrasmall SPION encapsulation with PEG-PCL micelles (PEG-PCL-SPIONs) simultaneously increases transverse (r2) and decreases longitudinal (r1) magnetic resonance (MR) relaxivities of water proton in micelle solution, leading to a notably high r2/r1 ratio up to 78, which makes the PEG-PCL-SPIONs a highly sensitive MR imaging (MRI) T2 contrast agent. The mean size of folate-attached SPION micelles (Fa-PEG-PCL-SPIONs) is 44 ± 3 nm on average, ideal for in vivo MRI applications in which long circulation is greatly determined by small particle size and is highly desirable. Prussian blue staining of BEL-7402 cells over-expressing folate receptors, after incubation with micelle-containing medium, demonstrated that folate functionalization of the magnetic particles significantly enhanced their cell uptake. The potential of Fa-PEG-PCL-SPIONs as a potent MRI probe for in vivo tumor detection was assessed. At 3 hours after intravenous injection of the Fa-PEG-PCL-SPION solution into mice bearing subcutaneous xenografts of human BEL-7402 hepatoma, a 41.2% signal intensity decrease was detected in the T2-weighted MR images of the tumor, indicating the efficient accumulation of Fa-PEG-PCL-SPIONs in the tumor tissue.

Magnetic resonance imaging appearances of different discovertebral lesions.

Magnetic resonance imaging (MRI) is not only an excellent imaging modality for the demonstration of morphological changes but is also capable of providing pathophysiological and pathoanatomic information about various spinal diseases. Different techniques offer opportunities to demonstrate the degree of water content, the vascularity of tissue components, the accumulation of fat, and new bone production. Thus MRI closely reflects the initial phase as well as the progression of pathoanatomic changes during the evolution of a disease. Due to the high sensitivity of MRI, abnormalities are often established at an early stage of discovertebral disease, when etiological diagnosis may be difficult. The specificity of MRI findings lags behind its sensitivity; similar changes can be demonstrated in etiologically different disease entities, which reflects the limited reactive possibilities of the osteoarticular system. In fact, the MRI morphological and signal intensity features of different discovertebral lesions are commonly determined more by their location and by the reactive capabilities of disc and bone than by their etiology. Early and exact MRI differentiation of various discovertebral lesions is of the utmost clinical importance for prompt institution of appropriate therapy.

The role of MRI in dementia.

Neuroimaging techniques aimed at studying structural changes of the brain may provide useful information for the diagnosis and the clinical management of patients with dementia. Magnetic resonance imaging (MRI) may show abnormalities amenable to surgical treatment in a significant percentage of patients with cognitive impairment. MRI may also assist the differential diagnosis in dementia associated with metabolic or inflammatory diseases.MRI has the potential to detect focal signal abnormalities which may assist the clinical differentiation between Alzheimer's disease (AD) and vascular dementia (VaD). Severe temporal atrophy, hyperintensities involving the hippocampal or insular cortex, and gyral hypointense bands are more frequently noted in AD. Basal ganglionic/thalamic hyperintense foci, thromboembolic infarctions, confluent white matter and irregular periventricular hyperintensities are more common in VaD. The high sensitivity of MRI in detecting T2 hyperintense lesions and the low specificity off white matter lesions have resulted in a poor correlation between MRI findings and both neuropathological and clinical manifestations. In particular, MRI has disclosed a series of white matter focal changes in the elderly population, which are not necessarily associated with cognitive dysfunction. The recent advent of a new MRI method sensitive to the microstructural changes of white matter, the so-called diffusion tensor imaging, may be helpful in correlating clinical manifestations with white matter abnormalities.

The Role of Magnetic Resonance Imaging in Central Hearing Deficits: Beyond the Acoustic Schwannoma

Acoustic schwannoma is assumed to be the most common cause of sensory-neural hearing loss (SNHL), and many papers have described the role of magnetic resonance imaging (MRI) in the diagnosis of cerebello-pontine angle (CPA) tumours, particularly schwannoma. We retrospectively examined 72 patients complaining of different clinical syndromes and SNHL or different kinds of acoustic impairment who underwent MRI brain study excluding the presence of acoustic schwannoma and other CPA masses. In conclusion, although acoustic schwannoma is the most common cause of acquired HD, a lesion involving the neural centers of the acoustic pathway can also determine SNHL or HD. Considering the high sensitivity of MRI in the detection of acoustic intra-axial pathway lesions, an in-depth MRI examination of the brain stem and the temporal lobe is mandatory when SNHL or HD occur in patients not affected by acoustic schwannoma.

Magnetic resonance imaging of inflammatory reaction in osteoid osteoma.

Between 1988 and 1993, 16 cases of osteoid osteoma were examined by magnetic resonance imaging (MRI). MRI clearly visualized the extent of inflammation in the bone marrow and soft parts that is difficult to observe with other diagnostic techniques. The degree of inflammation varied among the patients. This might be associated with the anatomical relationship between the nidus and the cortex. The high sensitivity of MRI, unfortunately, may lead to an erroneous interpretation in lesions accompanied by inflammatory responses of the bone marrow or soft parts, such as osteoid osteoma. However, these reactions on MRI may offer a key to the pathogenesis of osteoid osteoma, a unique bone neoplasm.

Radiation-induced insufficiency fractures of the sacrum: evaluation with MR imaging.

In patients with malignant pelvic tumors, radiation-induced insufficiency fractures of the sacrum may be mistaken for metastasis. Magnetic resonance (MR) imaging was performed in 18 patients with this condition, and the findings were studied retrospectively. The diagnosis was confirmed with at least one additional imaging modality in 16 patients, whereas the other two patients underwent clinical follow-up at 13 and 20 months without evidence of metastasis. In 17 patients, the lesions were consistent with edema and had diffuse low signal intensity on T1-weighted images and diffuse high signal intensity on short-inversion-time inversion-recovery images, thereby simulating metastasis. In one patient, bilateral sacral wing fractures were demonstrated directly as fairly well-defined linear zones. The alae sacri were involved in all patients; 16 patients had bilateral lesions. Awareness of this clinical entity and of the high sensitivity of MR imaging for demonstrating edema caused by the fracture should prevent confusion with metastatic disease and inappropriate treatment.

Magnetic Resonance Imaging, Computed Tomography, and Autopsy Findings after Cardiorespiratory Arrest

A 29-year-old man had temporary cardiorespiratory arrest. Eight hours later, magnetic resonance imaging (MRI) of the brain revealed scattered hyperintense gyri and a marked high signal intensity of the caudate nuclei and the putamen. Computed tomography (CT) displayed no focal abnormalities but only diffuse brain swelling and blood in the subarachnoid space. The patient died 17 hours after the arrest. Histopathological findings were consistent with early ischemic brain damage. Perivascular infiltrates, probably inflammatory, involved the entire brainstem. Neither MRI nor CT demonstrated brainstem encephalitis, the presumed cause for the arrest. This observation suggests a high sensitivity of MRI for cerebral damage caused by global hypoxemia, yielding valuable diagnostic and prognostic information after resuscitation.