Amino Acid Tracer PET MRI in Glioma Management: What a Neuroradiologist Needs to Know.

PET with amino acid tracers provides additional insight beyond MR imaging into the biology of gliomas that can be used for initial diagnosis, delineation of tumor margins, planning of surgical and radiation therapy, assessment of residual tumor, and evaluation of posttreatment response. Hybrid PET MR imaging allows the simultaneous acquisition of various PET and MR imaging parameters in a single investigation with reduced scanning time and improved anatomic localization. This review aimed to provide neuroradiologists with a concise overview of the various amino acid tracers and a practical understanding of the clinical applications of amino acid PET MR imaging in glioma management. Future perspectives in newer advances, novel radiotracers, radiomics, and cost-effectiveness are also outlined.

Applications of chitosan for improvement of quality and shelf life of foods: a review.

Chitosan is a modified, natural biopolymer derived by deacetylation of chitin, a major component of the shells of crustacean. Recently, chitosan has received increased attention for its commercial applications in the biomedical, food, and chemical industries. Use of chitosan in food industry is readily seen due to its several distinctive biological activities and functional properties. The antimicrobial activity and film-forming property of chitosan make it a potential source of food preservative or coating material of natural origin. This review focuses on the applications of chitosan for improvement of quality and shelf life of various foods from agriculture, poultry, and seafood origin.

Melorheostosis involving the cervical and upper thoracic spine: radiographic, CT, and MR imaging findings.

Melorheostosis, an uncommon mesenchymal dysplasia, rarely affects the axial skeleton. We describe the imaging findings of melorheostosis involving the cervical and upper thoracic spine. Radiographs and CT showed unilateral well-marginated undulating zones of cortical hyperostosis involving multiple vertebrae that were contiguous with a coalescent ossified right paravertebral mass. MR imaging showed zones of signal intensity void on all pulse sequences without contrast enhancement. Conservative management was elected because of lack of interval clinical and imaging changes for 8 years.

Primary intracranial atypical teratoid/rhabdoid tumors of infancy and childhood: MRI features and patient outcomes.

BACKGROUND AND PURPOSE: Primary atypical teratoid/rhabdoid tumors (AT/RTs) are rare malignant intracranial neoplasms, usually occurring in young children. The objectives of this study were to characterize the MR imaging features and locations of primary intracranial AT/RTs, to determine the frequency of disseminated disease in the central nervous system (CNS) at diagnosis and postoperatively, and to assess patient outcomes. METHODS: The preoperative cranial MR images of 13 patients with AT/RTs were retrospectively reviewed for evaluation of lesion location, size, MR signal intensity and enhancement characteristics, and the presence of disseminated intracranial tumor. Postoperative MR images of the head and spine for 17 patients were reviewed for the presence of locally recurrent or residual tumor and disseminated neoplasm. Imaging data were correlated with patient outcomes. RESULTS: Patients ranged in age from 4 months to 15 years (median age, 2.9 years). Primary AT/RTs were intra-axial in 94% of patients. The single primary extra-axial lesion was located in the cerebellopontine angle cistern. AT/RTs were infratentorial in 47%, supratentorial in 41%, and both infra- and supratentorial in 12%. A germ-line mutation of the hSNF5/INI1 tumor-suppressor gene was responsible for the simultaneous occurrence of an intracranial AT/RT and a malignant renal rhabdoid tumor in a 4-month-old patient. Mean tumor sizes were 3.6 x 3.8 x 3.9 cm. On short TR images, AT/RTs typically had heterogeneous intermediate signal intensity, as well as zones of low (54%), high (8%), or both low and high (31%) signal intensity from cystic and/or necrotic regions, hemorrhage, or both, respectively. On long TR/long TE images, solid portions of AT/RTs typically had heterogeneous intermediate-to-slightly-high signal intensity with additional zones of high (54%) or both high and low signal intensity (38%), secondary to cystic and/or necrotic regions, edema, prior hemorrhage, and/or calcifications. AT/RT had isointense and/or slightly hyperintense signal intensity relative to gray matter on fluid-attenuated inversion-recovery (FLAIR) and long TR/long TE images, and showed restricted diffusion. All except 1 AT/RT showed contrast enhancement. The fraction of tumor volume showing enhancement was greater than two thirds in 58%, between one third and two thirds in 33%, and less than one third in 9%. Disseminated tumor in the leptomeninges was seen with MR imaging in 24% of patients at diagnosis/initial staging and occurred in another 35% from 4 months to 2.8 years (mean, 1.1 years) after surgery and earlier imaging examinations with negative findings. The overall 1-year and 5-year survival probabilities were 71% and 28%, respectively. Patients with MR imaging evidence of disseminated leptomeningeal tumor had a median survival rate of 16 months compared with 149 months for those without disseminated tumor (P < .004, logrank test). CONCLUSION: AT/RTs are typically intra-axial lesions, which can be infra- and/or supratentorial. The unenhanced and enhanced MR imaging features of AT/RT are often variable secondary to cystic/necrotic changes, hemorrhage, and/or calcifications. Poor prognosis is associated with MR imaging evidence of disseminated leptomeningeal tumor.

The role of surveillance magnetic resonance imaging (MRI) scanning in detecting recurrent brain tumors in asymptomatic children.

BACKGROUND: There is controversy regarding the utility of routine surveillance scanning for asymptomatic children with brain tumors. Although the role of CT or magnetic resonance imaging (MRI) scanning in this setting has been examined in several studies, none have focused on children followed exclusively by MRI. The purpose of this study was to determine how often recurrent brain tumors are detected by routine MRI surveillance in asymptomatic children. METHODS: The medical records of all children with brain tumors treated at Children's Hospital at Strong from 1990-1999 were reviewed. Recurrence was defined as an increase in size of the tumor on MRI scan. Astrocytomas and gangliogliomas were classified as low-grade tumors; high-grade astrocytomas, medulloblastomas, and ependymomas were classified as high-grade tumors. RESULTS: Of the 112 evaluable children with brain tumors during this time period, 46 (41%) suffered an MRI-documented recurrence. Of these 46 patients, 13 (28%) had low-grade tumors and 33 (72%) had high-grade tumors. Twenty-seven of the 46 recurrences (59%) occurred in asymptomatic children. Ten of the 13 children (77%) with recurrent low-grade tumors were asymptomatic compared to 17 of 33 children (52%) with recurrent high-grade tumors (p = 0.18). The median survival from time of recurrence for the symptomatic children was seven months, while the median survival from time of recurrence for the asymptomatic children has not yet been reached (p = 0.025). When the analysis was confined to children with high-grade tumors, there was no difference in median survival from the time of recurrence for symptomatic versus asymptomatic children (5 mo. versus 7 mo.) (p = 0.25). The frequency of detection of recurrences by surveillance scanning in asymptomatic children was 4.2% (one recurrence detected per 24 surveillence MRI scans). CONCLUSION: The majority of recurrent brain tumors are detected by MRI surveillence in asymptomatic children. However, asymptomatic recurrences were detected in only a small proportion of surveillance scans and had no impact on survival in children with high-grade tumors.

Postoperative evaluation for disseminated medulloblastoma involving the spine: contrast-enhanced MR findings, CSF cytologic analysis, timing of disease occurrence, and patient outcomes.

BACKGROUND AND PURPOSE: Postoperative MR imaging is routinely performed for staging of medulloblastoma because of frequent tumor dissemination along CSF pathways. The goals of this study were to: 1) determine the timing of disease occurrence and contrast-enhanced MR imaging features of disseminated medulloblastoma involving the spine and their relationship to patient outcomes; and 2) compare the diagnostic accuracy of MR imaging findings with CSF cytologic analysis. METHODS: Medical records, pathologic reports, and unenhanced and contrast-enhanced postoperative MR images of the spine and head from 112 patients who had resection of medulloblastoma were retrospectively reviewed. MR images of the spine were evaluated for abnormal contrast enhancement in the meninges and vertebral bone marrow. MR images of the head were evaluated for recurrent or residual intracranial tumor. Imaging data were correlated with available CSF cytologic results and patient outcomes. RESULTS: Twelve patients (11%) had tumor within the spinal leptomeninges depicted on MR images at the time of diagnosis. Twenty-five patients (22%) had disseminated disease in the spine (leptomeninges, n = 22; vertebral marrow, n = 1; or both locations, n = 2) on MR images 2 months to 5.5 years (mean, 2 years) after initial surgery and earlier negative imaging examinations. Eleven other patients (10%) had recurrent intracranial medulloblastoma without spinal involvement seen with MR imaging. Spinal MR imaging had a sensitivity of 83% in the detection of disseminated tumor, whereas contemporaneous CSF cytologic analysis had a sensitivity of 60%. The sensitivity of CSF cytologic analysis increased to 78% with acquisition of multiple subsequent samples, although diagnosis would have been delayed by more than 6 months compared with diagnosis by spinal MR imaging in six patients. Spinal MR imaging was found to have greater overall diagnostic accuracy than CSF cytologic analysis in the early detection of disseminated tumor (P = .03). Spinal MR imaging confirmed disseminated tumor when contemporaneous CSF cytologic findings were negative in 13 patients, whereas the opposite situation occurred in only two patients. False-positive results for spinal MR imaging and CSF cytologic analysis occurred when these examinations were obtained earlier than 2 weeks after surgery. The 5-year survival probability for patients with spinal tumor was 0.24 +/- 0.08 versus 0.68 +/- 0.05 for the entire study group. CONCLUSION: Spinal MR imaging was found to have greater diagnostic accuracy than CSF cytologic analysis in the early detection of disseminated medulloblastoma. CSF cytologic analysis infrequently confirmed disseminated tumor when spinal MR imaging results were negative. Delaying spinal MR imaging and CSF cytologic analysis by more than 2 weeks after surgery can reduce false-positive results for both methods. The presence of disseminated medulloblastoma in the spine seen with MR imaging is associated with a poor prognosis.

Effective deacetylation of chitin under conditions of 15 psi/121 degrees C.

Deacetylation of chitin under autoclaving conditions (15 psi/121 degrees C) was evaluated for the preparation of chitosan under different NaOH concentrations and reaction times. Deacetylation was effectively achieved by treatment of chitin under elevated temperature and pressure with 45% NaOH for 30 min and a solids/solvent ratio of 1:15. Treated chitosan showed similar nitrogen content (7.42%), degree of deacetylation (90.4%), and molecular mass (1560 kDa) but significantly higher viscosity values (2025 cP) compared with those (7.40%, 87.6%, 1304 kDa, and 143 cP, respectively) of a commercial chitosan. Reduction of the solids/solvent ratio from 1:15 to 1:10 did not affect degree of deacetylation, viscosity, and molecular mass of chitosan.

Associations between patient report of symptoms and anatomic impairment visible on lumbar magnetic resonance imaging.

STUDY DESIGN: A cross-sectional study comparing the relationship of symptoms with anatomic impairment visible on lumbar magnetic resonance imaging in 408 symptomatic subjects. OBJECTIVE: To determine how various anatomic impairments, including the magnitude and location of nerve compression visible on lumbar magnetic resonance imaging, are associated with patient reports of pain, weakness, and dysesthesia. SUMMARY AND BACKGROUND DATA: Anatomic impairments of the intervertebral disc, radicular canal, and associated soft tissues are prevalent in people with and those without low back pain or lower extremity radiculopathy. This has led to confusion in differentiating between symptom generators and benign variation visible on lumbar magnetic resonance imaging. Recent literature has suggested that the presence of nerve compression is an important finding in the prediction of symptoms. However, the threshold for meaningful nerve compression has not been described. METHODS: In this study, 408 participants undergoing a diagnostic workup for low back pain, radiculopathy, and/ or completed a survey and pain drawing. Participants underwent standardized lumbar magnetic resonance imaging using a 1.5-T scanner. Two classification systems describing the spatial distribution of symptoms were developed. An additional system to quantify the magnitude of nerve and thecal sac compression was created. All systems were assessed for reliability, after which comparisons among variables were performed using Chi2 as well as simple and multiple logistic regression analysis. RESULTS: The reliability coefficients for categorizing patients on the basis of pain drawing ranged from 0. 75 to 0.88. The S1-S2 segmental distribution was the most commonly reported location of symptoms, followed by L4-L5. The most common magnetic resonance imaging diagnosis was "unremarkable," followed by "disc impairment without nerve compression." Disc extrusion was present in 10.8% of participants. The reliability of classifying nerve compression visible on magnetic resonance imaging ranged from 0.27 to 1. Nerve compression was present in 37% of participants, and 18% had severe nerve compression. There were no significant associations between segmental distribution of symptoms and the presence of anatomic impairment. However, according to a collapsed classification scale, severe nerve compression and disc extrusion were predictive of pain distal to the knee (odds ratios, 2.72 and 3. 34). The self-report of weakness was associated mildly with severe nerve compression and disc extrusion, but not with other findings. Magnetic resonance imaging findings did not predict self-reports of dysesthesia. CONCLUSIONS: The presence of disc extrusion and/or ipsilateral, severe nerve compression at one or multiple sites is strongly associated with distal leg pain. Mild to moderate nerve compression, disc degeneration or bulging, and central spinal stenosis are not significantly associated with specific pain patterns. Although segmental distributions of pain can be determined reliably from pain drawings, this finding alone is of little use in predicting lumbar impairment. The self-report of lower extremity weakness or dysesthesia is not significantly related to any specific lumbar impairments. [Key words: back pain, diagnosis, magnetic resonance imaging, nerve compression, pain drawing, pathology]

Application of chitosan for treatment of wastewaters.

Research has clearly demonstrated that the biopolymer chitosan (deacetylated chitin) can be used as an effective coagulating agent for organic compounds, as a chelating polymer for binding toxic heavy metals, as well as an adsorption medium for dyes and small concentrations of phenols and PCBs present in various industrial wastewaters. In these specific applications, chitosan appears more effective than other polymers such as synthetic resins, activated charcoal, and even chitin itself. In addition, the amino group in chitosan is an effective functional group that can be altered chemically for production of other chitinous derivatives with specific useful characteristics as effective absorptive agents. Chitosans exhibiting different physicochemical characteristics, i.e., molecular weight, crystallinity, deacetylation, particle size, and hydrophilicity, differ in their effectiveness as waste treatment agents. The specific relationship between methods and the particular crustacean species used in preparation of chitosan for wastewater treatment needs further examination. Use of bioremediation approaches, combined with immobilization of specific microorganisms on immobilized chitinous columns, is an extremely promising area of current research and actual plant operation.

Developments in aquatic microbiology.

Major discoveries in marine microbiology over the past 4-5 decades have resulted in the recognition of bacteria as a major biomass component of marine food webs. Such discoveries include chemosynthetic activities in deep-ocean ecosystems, survival processes in oligotrophic waters, and the role of microorganisms in food webs coupled with symbiotic relationships and energy flow. Many discoveries can be attributed to innovative methodologies, including radioisotopes, immunofluorescent-epifluorescent analysis, and flow cytometry. The latter has shown the key role of marine viruses in marine system energetics. Studies of the components of the "microbial loop" have shown the significance of various phagotrophic processes involved in grazing by microinvertebrates. Microbial activities and dissolved organic carbon are closely coupled with the dynamics of fluctuating water masses. New biotechnological approaches and the use of molecular biology techniques still provide new and relevant information on the role of microorganisms in oceanic and estuarine environments. International interdisciplinary studies have explored ecological aspects of marine microorganisms and their significance in biocomplexity. Studies on the origins of both life and ecosystems now focus on microbiological processes in the marine environment. This paper describes earlier and recent discoveries in marine (aquatic) microbiology and the trends for future work, emphasizing improvements in methodology as major catalysts for the progress of this broadly-based field.

Magnetic resonance imaging in low back pain: general principles and clinical issues.

The purpose of this article is to provide an overview of the general principles of lumbar magnetic resonance imaging (MRI), including signal generation and image interpretation. Additionally, a discussion of the clinical usefulness as it relates to lumbar MRI is presented using degenerative disk disease as an example. Lumbar MRI provides high-resolution, multiaxial, multiplanar views that have high contrast between soft tissues. Obtaining these images in vivo creates minimal risk for patients and provides examiners with an excellent mechanism to study anatomic detail and the biochemical composition of the lumbar spine. Different tissue characteristics known as T1, T2, and proton density may be accentuated, allowing examiners to detect variations in tissue shape and hydration that may correspond to disease processes. There is strong agreement that lumbar MRI is indicated for the evaluation of patients with risk factors for neoplastic or infectious disorders or in persons with coexisting evidence of neurologic impairment. The utilization of lumbar MRI in patients with low back pain (LBP), however, is controversial. Lumbar MRI has a high technical capacity to detect degenerative disk disease, bulging and herniated disks, and distortions in the thecal sac or nerve roots associated with these conditions. The diagnostic accuracy, however, of most lumbar anatomic impairments related to the symptoms of LBP is low or unknown. Although lumbar MRI remains as an excellent tool to study morphology, findings must be related to data from clinical examinations to provide meaningful judgments.

Magnetic resonance imaging: a cost-effective alternative to bone scintigraphy in the evaluation of patients with suspected hip fractures.

OBJECTIVE: To evaluate the cost-effectiveness of magnetic resonance imaging (MRI) compared with radionuclide bone scan in the evaluation of patients with clinically suspected hip fractures. DESIGN: The medical records of all patients who had been seen in the emergency room over a 4 1/2 year period with a clinically suspected hip fracture, negative or equivocal plain films, and either a subsequent bone scan or MRI examination were retrospectively reviewed. The time to diagnosis, admission rate, and time to surgery were determined. A two-sample t-test was used to assess the statistical significance of the results. A theoretical cost analysis was performed using current charges to estimate all expenses. PATIENTS: Forty patients (11 male, 29 female; age 28-99 years) satisfied our inclusion criteria. RESULTS AND CONCLUSIONS: Twenty-one patients had bone scans (six with fractures), and 19 had MRI (four with fractures). The time to diagnosis was 2.24 +/- 1.30 days for bone scanning and 0.368 +/- 0.597 days for MRI (P < 0.0001). Twenty patients in the bone scan group were admitted compared with 13 in the MRI group. The time to surgery was at least 1 day longer in patients undergoing bone scanning. Bone scanning resulted in higher patient costs compared with MRI because of the delay in diagnosis. In the evaluation of patients with suspected hip fractures, early MRI is more cost-effective than delayed bone scanning. Further prospective studies comparing the cost-effectiveness of early MRI with early bone scanning are needed.

Magnetic resonance imaging of the hip with a pelvic phased-array surface coil: a technical note.

OBJECTIVE: The aim of this study was to assess the capability of high-resolution images obtained with a commercially available pelvic phased-array surface coil to demonstrate normal hip anatomy. DESIGN: We retrospectively analyzed the oblique coronal magnetic resonance (MR) images of hips of 36 consecutive patients acquired on a 1.5-T clinical imager using a pelvic phased-array coil as a receiver, a 16-20 cm field of view, and 5 mm slice thickness. PATIENTS: Thirty-six patients were studied, age 15-81 years. There were 20 males and 16 females. RESULTS AND CONCLUSIONS: The articular cartilage, cortex, superior labrum, and iliofemoral ligament were well visualized on proton density weighted fat saturation (PDF) images. The femoral and obturator vessels, obturator nerve, and various muscles were easily seen on T1-weighted images. High-resolution imaging of the hip is achievable in a reasonable amount of time using newer phased-array surface coils and may play an increasing role in the future evaluation of hip disorders.

Primary solitary amyloidosis of the spine: a case report and review of the literature.

BACKGROUND: Amyloidosis is a term that encompasses a group of disorders that have as their common feature the intercellular deposition of the amyloid protein by several different pathogenetic mechanisms. Primary solitary amyloidosis, or amyloidoma, is a rare subset of amyloidosis in which the amyloid deposition is focal and not secondary to a systemic process or plasma cell dyscrasia. We present the second reported case of a cervical spine amyloidoma and discuss its presentation and management. METHODS: This 58-year-old man presented with a 1-year history of intermittent chest pain that would radiate into both legs precipitated by valsalva maneuvers. A magnetic resonance imaging (MRI) of the cervical spine revealed a homogenously enhancing lesion focally involving the C-7 vertebral level with significant spinal cord compression. He underwent combined anterior and posterior decompressive procedures with instrumentation for spinal stabilization. Histopathology revealed amyloid deposits and a systemic work-up was negative for amyloidosis. RESULTS: The patients is free of any tumor recurrence at 24 months and has a stable spine construct. CONCLUSIONS: Primary solitary amyloidosis is a rare subtype of amyloidosis which, unlike other forms of amyloidosis, has an excellent prognosis with local resection. Diagnosis requires special stains and therefore a degree of suspicion for the disease. Management of vertebral amyloidoma involves aggressive local resection of the tumor when feasible and stabilization of the spine as mandated by the degree of tumor involvement. Complete evaluation for the diagnosis of systemic amyloidosis is essential for the management and prognostication of each case.

Parallel processing streams in human visual cortex.

This study shows the existence in humans of independent neural processing streams in early visual cortex, which had previously been demonstrated in macaque monkeys. This evidence was obtained by controlled fixation testing of a subject who had suffered a small stroke in the right fusiform gyrus. The patient showed a severe disruption of color perception, shape discrimination and contrast sensitivity for stationary gratings in the upper left quadrant of his visual field. However, motion perception and contrast sensitivity for drifting gratings were relatively preserved. These results support the view that there are independent visual processing streams early in human visual cortex, and that these streams may subserve such functions as motion and color/form perception.

Lesions of the triangular fibrocartilage complex: MR findings with a three-dimensional gradient-recalled-echo sequence.

PURPOSE: To evaluate the use of a three-dimensional gradient-recalled-echo (GRE) magnetic resonance (MR) imaging sequence in the depiction of lesions of the triangular fibrocartilage (TFC) complex. MATERIALS AND METHODS: MR images of the TFC complex were evaluated in 31 patients who underwent wrist arthroscopy less than 6 months after MR imaging. The results were compared with the arthroscopic findings. RESULTS: Eleven of 12 full-thickness TFC tears were depicted, but one partial-thickness tear, one abnormal disk, and one normal disk were overstaged. Lesions in the volar and dorsal radioulnar ligament and lesions of the attachments of the TFC complex to the ulna often were overstaged. Lesions of the ulnolunate and ulnotriquetral ligaments often were understaged. CONCLUSION: Imaging with the three-dimensional GRE sequence is reliable in the depiction of TFC tears and the exclusion of tears of components of the TFC complex other than those of the ulnolunate and ulnotriquetral ligaments.

Pyomyositis: diagnostic value of color Doppler sonography.

The color Doppler sonographic appearance of pyomyositis and the usefulness of this technique in guiding needle aspiration of an intramuscular abscess in a 15-year-old diabetic girl are described.