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Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Dental Press Journal of Orthodontics is the property of Dental Press International and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Dental Science is the property of Brazilian Dental Science Journal-ICT-UNESP and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To evaluate the usefulness of Anali scores, determined by magnetic resonance imaging, for predicting the prognosis of primary sclerosing cholangitis (PSC) and to analyze interobserver variability, as well as to assess the impact of periportal edema and heterogeneous signal intensity on diffusion-weighted imaging of the liver. Materials and Methods: This was a retrospective cohort study of 29 patients with PSC and baseline magnetic resonance imaging. Anali scores, without gadolinium (0-5 points) and with gadolinium (0-2 points), were calculated by two radiologists. Clinical endpoints included liver transplantation, cirrhotic decompensation, and death. We calculated intraclass correlation coefficients (ICCs) for interobserver agreement on the Anali scores, performed Kaplan-Meier survival analysis comparing event-free survival among the score strata, and calculated the areas under receiver operating characteristic curves to determine sensitivity and specificity. Results: Among the patients with a clinical event, the median Anali score was 4 (interquartile range [IQR], 2-5) without gadolinium and 2 (IQR, 1-2) with gadolinium, compared with 1 (IQR, 1.0-2.5) and 1 (IQR, 0.25-1.0), respectively, among those without a clinical event. The ICC was 0.79 (95% confidence interval: 0.57-0.91) for the Anali score with gadolinium and 0.99 (95% confidence interval: 0.98-0.99) for the Anali score without gadolinium. Periportal edema and heterogeneous signal intensity in the liver on diffusion-weighted imaging showed no statistical impact on clinical events (p = 0.65 and p = 0.5, respectively). Conclusion: Anali scores correlate with clinical events in PSC, with a high level of interobserver agreement. [ABSTRACT FROM AUTHOR]

Objective: To determine the association between medial femoral condyle hypoplasia and trochlear dysplasia by analyzing the knee magnetic resonance imaging scans of young patients with or without trochlear dysplasia. Materials and Methods: This was a retrospective analysis of magnetic resonance imaging scans of the knees of young individuals (16-35 years of age): 30 patients with trochlear dysplasia and 30 individuals with no signs of patellofemoral instability. The ratios between the depth, width, and height of the medial and lateral femoral condyles (dLC/dMC, wLC/wMC, and hLC/hMC, respectively) were calculated, as was the ratio between the width of the medial condyle and the total width of the femur (wMC/FW). All of the values were determined in consensus by two radiologists. Results: We evaluated 60 patients: 30 with trochlear dysplasia and 30 without. The mean dLC/dMC, wLC/wMC, and hLC/hMC ratios were higher in the patients than in the controls (p < 0.05), whereas the mean wMC/FW ratio was lower in the patients (p < 0.05). The optimal cutoff values, obtained by calculating the areas under the receiver operating characteristic curves, were 1.0465 for the dLC/dMC ratio (76% sensitivity and 63.3% specificity), 0.958 for the wLC/wMC ratio (80% sensitivity and 73.3% specificity), and 1.080 for the hLC/hMC ratio (93.3% sensitivity and 93.3% specificity). Conclusion: Our findings confirm our hypothesis that trochlear dysplasia is associated with medial condyle hypoplasia. [ABSTRACT FROM AUTHOR]

Objective: To compare the measurements of the lumbar safety triangle (Kambin's triangle) and the invasion of the dorsal root ganglion in the triangle in coronal and coronal oblique planes. Materials and Methods: A cross-sectional study, in which 210 3.0-T magnetic resonance images of L2-L5 were analyzed in coronal and coronal oblique planes. Exams with lumbar spine anomalies were excluded. Demographic (sex and age) and radiological variables were recorded by a single evaluator. Results: Most sample was female (57.1%), mean age 45.5 ± 13.3 (18-98 years). The measurements average, as well as the areas, gradually increased from L2 to L5. The dorsal root ganglion invaded the triangle in all images. The safety triangle average area was smaller in the coronal oblique plane than in the coronal plane. Of the seven dimensions of safety triangle obtained for each level of the lumbar spine, six were significantly smaller in the coronal oblique plane than in the coronal plane. The only dimension that showed no difference was the smallest ganglion dimension. Conclusion: The dimensions and areas investigated were smaller in coronal oblique plane, especially the area (difference > 1 mm). The analysis of the triangular zone in this plane becomes important in the preoperative assessment of minimally invasive procedures. [ABSTRACT FROM AUTHOR]

Objective: To determine the frequency and interobserver reproducibility of the magnetic resonance imaging (MRI) features considered diagnostic for autoimmune hepatitis. Materials and Methods: Two abdominal radiologists, blinded to pathology data, reviewed the MRI examinations of 20 patients with autoimmune hepatitis, looking for liver enhancement, lymphadenopathy, portal hypertension, and chronic liver disease. The pattern of liver fibrosis was categorized as reticular, confluent, or mixed. Interobserver agreement was assessed by calculating intraclass correlation coefficients and kappa statistics. Results: The most common abnormal finding on MRI was surface nodularity (in 85%), followed by liver fibrosis with a reticular pattern (in 80%)--categorized as mild (in 25.0%), moderate (in 43.8%), or severe (in 31.2%)--; heterogeneous liver enhancement (in 65%); splenomegaly (in 60%); caudate lobe enlargement (in 50%); and lymphadenopathy (in 40%). The interobserver agreement was almost perfect for surface nodularity (0.83), ascites (0.89), and liver volume (0.95), whereas it was just slight and fair for the degree of fibrosis and for heterogeneous liver enhancement (0.12 and 0.25, respectively). It was also slight and fair for expanded gallbladder fossa and enlarged preportal space (0.14 and 0.36, respectively), both of which are indicative of chronic liver disease. Conclusion: The interobserver agreement was satisfactory for surface nodularity (the most prevalent abnormal MRI finding), ascites, liver volume, and splenomegaly. Conversely, it was only slight or fair for common but less objective criteria. [ABSTRACT FROM AUTHOR]

Objective: To demonstrate that positive predictive values (PPVs) for suspicious (category 4) magnetic resonance imaging (MRI) findings that have been stratified are equivalent to those stipulated in the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) for mammography and ultrasound. Materials and Methods: This retrospective analysis of electronic medical records generated between January 4, 2016 and December 29, 2021 provided 365 patients in which 419 suspicious (BI-RADS category 4) findings were subcategorized as BI-RADS 4A, 4B or 4C. Malignant and nonmalignant outcomes were determined by pathologic analyses, follow-up, or both. For each subcategory, the level 2 PPV (PPV2) was calculated and tested for equivalence/noninferiority against the established benchmarks. Results: Of the 419 findings evaluated, 168 (40.1%) were categorized as malignant and 251 (59.9%) were categorized as nonmalignant. The PPV2 for subcategory 4A was 14.2% (95% CI: 9.3-20.4%), whereas it was 41.2% (95% CI: 32.8-49.9%) for subcategory 4B and 77.2% (95% CI: 68.4-84.5%) for subcategory 4C. Multivariate analysis showed a significantly different cancer yield for each subcategory (p < 0.001). Conclusion: We found that stratification of suspicious findings by MRI criteria is feasible, and malignancy probabilities for subcategories 4B and 4C are equivalent to the values established for the other imaging methods in the BI-RADS. Nevertheless, low suspicion (4A) findings might show slightly higher malignancy rates. [ABSTRACT FROM AUTHOR]

A esclerose múltipla é a doença desmielinizante do sistema nervoso central mais frequente, caracterizando-se pelo início precoce e incapacidade progressiva. A ressonância magnética, pela elevada sensibilidade e especificidade na deteção de lesões desmielinizantes, é o exame complementar mais útil nesta patologia, sendo a administração de meios de contraste com gadolínio um importante contributo na interpretação imagiológica. Embora o contraste seja imprescindível no âmbito do diagnóstico, a sua utilização por rotina na monitorização da atividade de doença, resposta ao tratamento e respetivas complicações é controversa. O objetivo deste artigo é reunir as recomendações atuais relativas à utilização do gadolínio no seguimento imagiológico da esclerose múltipla e definir um protocolo clínico efetivo e seguro. A revisão da literatura foi conduzida na PubMed, recorrendo aos termos ‘esclerose múltipla’, ‘ressonância magnética’ e ‘gadolínio’ ou ‘meio de contraste’. Foram selecionados artigos publicados entre janeiro de 2013 e de 2023 relativos à segurança do gadolínio e à sua utilização na ressonância magnética de controlo dos doentes adultos com diagnóstico de esclerose múltipla. Apesar de nenhuma consequência biológica ou clínica ter sido inequivocamente atribuída à retenção cerebral do gadolínio, que foi reportada maioritariamente com agentes lineares, as autoridades de saúde têm vindo a recomendar a restrição do contraste a circunstâncias clínicas essenciais. Na esclerose múltipla, a deteção de lesões subclínicas com captação de gadolínio sem tradução em lesões novas/aumentadas nas sequências ponderadas em T2 ocorre raramente e com impacto na decisão terapêutica questionável. Por outro lado, o gadolínio assume uma sensibilidade superior no diagnóstico diferencial de surtos clínicos, na deteção de atividade inflamatória recente, antes e após o início de uma terapêutica e nos doentes com elevada carga lesional ou lesões difusas/confluentes nas sequências ponderadas em T2. Contrariamente ao rastreio da leucoencefalopatia multifocal progressiva, a monitorização da síndrome inflamatória de reconstituição imunológica beneficia também da inclusão do gadolínio. É exequível e segura a exclusão do gadolínio no seguimento imagiológico de rotina da esclerose múltipla, apesar do seu contributo adicional em circunstâncias clínicas específicas que devem ser do conhecimento articulado do neurologista e neurorradiologista.

Reportamos um caso de uma paciente do sexo feminino, 17 anos, com grande massa mamária palpável e história prévia de rabdomiossarcoma orbitário diagnosticado dezoito meses antes. Após exames de imagem e biópsia percutânea, foi realizado o diagnóstico de metástase de rabdomiossarcoma do tipo alveolar.

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To analyze the association between osteolysis at the prosthesis interfaces, as determined by magnetic resonance imaging (MRI) with multiacquisition variable-resonance image combination selective (MAVRIC-SL) sequences, and clinical severity after knee or hip arthroplasty, as well as to assess interobserver and intraobserver agreement on periprosthetic bone resorption. Materials and Methods: This was a cross-sectional study of 47 patients (49 joints) under postoperative follow-up after knee or hip arthroplasty, with chronic pain, between March 2019 and August 2020. All of the patients completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. The component interfaces were evaluated and ordered into two groups: osseointegrated and osteolytic. Nonparametric tests were used. Results: There were significant differences between the two groups in terms of the mean WOMAC scores: total (p = 0.010); stiffness domain (p = 0.047); and function (p = 0.011) domains. There was substantial interobserver and intraobserver agreement for most analyses of the components. Conclusion: Periprosthetic osteolysis appears to be associated with clinical complaints of pain in the post-arthroplasty scenario, and MAVRIC-SL provides reproducible assessments. It could prove to be an important tool for orthopedists to use in the evaluation of challenging cases of chronic pain after arthroplasty. [ABSTRACT FROM AUTHOR]

We report a case of a 17-year-old female patient with a large palpable breast mass and a prior history of orbital rhabdomyosarcoma diagnosed 18 months earlier. After imaging studies and percutaneous biopsy, the diagnosis of alveolar rhabdomyosarcoma metastasis was established. [ABSTRACT FROM AUTHOR]

Objective: To present an update of the recommendations of the Brazilian College of Radiology and Diagnostic Imaging, the Brazilian Society of Mastology, and the Brazilian Federation of Gynecology and Obstetrics Associations for breast cancer screening in Brazil. Materials and Methods: Scientific evidence published between January 2012 and July 2022 was gathered from the following databases: Medline (PubMed); Excerpta Medica (Embase); Cochrane Library; Ebsco; Cumulative Index to Nursing and Allied Health Literature (Cinahl); and Latin-American and Caribbean Health Sciences Literature (Lilacs). Recommendations were based on that evidence and were arrived at by consensus of a joint committee of experts from the three entities. Recommendations: Annual mammographic screening is recommended for women between 40 and 74 years of age. For women at or above the age of 75, screening should be reserved for those with a life expectancy greater than seven years. Women at higher than average risk are considered by category: those with dense breasts; those with a personal history of atypical lobular hyperplasia, classical lobular carcinoma in situ, or atypical ductal hyperplasia; those previously treated for breast cancer; those having undergone thoracic radiotherapy before age 30; and those with a relevant genetic mutation or a strong family history. The benefits of complementary screening are also addressed according to the subcategories above. The use of tomosynthesis, which is an evolved form of mammography, should be considered in screening, whenever accessible and available. [ABSTRACT FROM AUTHOR]

Objective: To describe cases of parafoveal chondral lesion of the femoral head in patients with femoroacetabular impingement, correlating the clinical and imaging data. Materials and Methods: This was a retrospective descriptive case series of parafoveal chondral lesion of the femoral head in 21 patients who underwent computed tomography and magnetic resonance arthrography scans of the hip, having then received an imaging-based diagnosis of femoroacetabular impingement. Results: Of the 21 patients evaluated, 15 (71%) had cam-type femoroacetabular impingement, whereas five (24%) had mixed-type impingement, and one (5%) had pincer-type impingement. Twelve patients (57%) had a low frequency of physical activity, which was significantly associated with the presence of cam-type impingement (p = 0.015). Although the extent of the lesion correlated significantly with the acetabular coverage angle (p = 0.04), it did not correlate significantly with the alpha angle or femoral head-neck offset value (p = 0.08 and p = 0.06, respectively). We also found no correlation between the extent of the lesion and the other main parameters that define the femoroacetabular impingement types. Conclusion: This was one of the largest case series of parafoveal chondral lesion of the femoral head in patients with imaging findings of femoroacetabular impingement. The extent of such lesions does not appear to correlate with the parameters of femoroacetabular impingement, with the exception of the acetabular coverage angle. [ABSTRACT FROM AUTHOR]

Objective: To describe the clinical and radiological evolution of lesions during and after treatment in patients diagnosed with neuroparacoccidioidomycosis (NPCM). Materials and Methods: This was a retrospective study of the medical records, computed tomography scans, and magnetic resonance imaging (MRI) scans of patients with NPCM treated between September 2013 and January 2022. Results: Of 36 cases of NPCM, eight were included in the study. One patient presented only with pachymeningeal and skull involvement, and seven presented with pseudotumors in the brain. Collectively, the eight patients presented with 52 lesions, of which 46 (88.5%) were supratentorial. There were 32 lesions with a diameter ≤ 1.2 cm, of which 27 (84.4%) disappeared during the treatment. In three cases, there were lesions > 1.2 cm that showed a characteristic pattern of evolution on MRI: an eccentric gadolinium contrast-enhanced nodule, with a subsequent decreased in the size and degree of contrast enhancement of the lesions. Conclusion: In NPCM, supratentorial lesions seem to predominate. Lesions ≤ 1.2 cm tend to disappear completely during treatment. Lesions > 1.2 cm tend to present with a similar pattern, designated the "Star of Bethlehem sign", throughout treatment. [ABSTRACT FROM AUTHOR]

Objective: To characterize the location of tibial edema related to meniscal degeneration with a flap displaced into the meniscotibial recess (osteomeniscal impingement) on magnetic resonance imaging (MRI). Materials and Methods: We evaluated 40 MRI examinations of patients submitted to surgery due to inferior displacement of a meniscal flap tear into the meniscotibial recess and peripheral bone edema. Tibial edema was quantified in the coronal and axial planes. Results: On coronal MRI sequences, edema started in the tibial periphery and extended for a mean of 5.6 ± 1.4 mm, or 7.4 ± 2.1% of the tibial plateau. In the craniocaudal direction, the mean extension was 8.8 ± 2.9 mm. The mean ratio between the extent of craniocaudal and mediolateral edema was 1.6 ± 0.6. In the axial plane, the edema started in the medial periphery and extended for a mean of 6.2 ± 2.0 mm, or 8.2 ± 2.9% of the tibial plateau. In the anteroposterior measurement, the mean start and end of the edema was 21.4 ± 5.4 mm and 35.7 ± 5.7 mm, respectively, or 43.4 ± 10.2% and 72.8 ± 11.1% of the tibial plateau. Conclusion: Apparently, tibial edema resulting from osteomeniscal impingement always starts in the periphery of the meniscus. In the coronal plane, it appears to be more extensive in the craniocaudal direction than in the mediolateral direction. In the axial plane, we found it to extend, on average, approximately 6.2 mm in the mediolateral direction and to be most commonly located from the center to the posterior region of the medial tibial plateau. [ABSTRACT FROM AUTHOR]

Radiation-induced secondary tumors constitute a rare complication of radiation therapy and typically occur in or near the irradiated area. Women who undergo thoracic radiotherapy before 30 years of age have a significantly greater lifetime risk of developing breast cancer than do those in the general population. It is recommended that a patient who has previously received thoracic radiotherapy with a radiation dose = 10 Gy subsequently undergo annual screening with mammography and magnetic resonance imaging, beginning eight years after the initial treatment or when the patient has reached 25 years of age (whichever comes later). The treatment of secondary breast cancer in this population should be individualized and should be discussed with a multidisciplinary team to avoid toxicity related to the treatment of the primary cancer. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Dental Science is the property of Brazilian Dental Science Journal-ICT-UNESP and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The temporomandibular joint can be affected by various conditions, such as joint dysfunction, degenerative changes, inflammatory processes, infections, tumors, and trauma. The aim of this pictorial essay is to help radiologists identify and describe the main findings on magnetic resonance imaging evaluation of the temporomandibular joint, given that the correct diagnosis is essential for the appropriate treatment of patients with temporomandibular joint disorders. [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma is one of the most aggressive malignant neoplasms, with a one-year survival rate below 20%. Axial methods (computed tomography and magnetic resonance imaging) play a fundamental role in the diagnosis and staging of the disease, because they provide adequate anatomical resolution in the assessment of key structures, mainly vascular structures. Pancreatic ductal adenocarcinoma is most often discovered in advanced stages, when surgical resection is no longer feasible. In that scenario, minimally invasive treatment alternatives have been developed in attempts to change the natural history of the disease. Irreversible electroporation, an interventional procedure that minimizes deleterious effects on adjacent tissues, has proven useful for the treatment of tumors traditionally considered unresectable. Despite the growing acknowledgment of this technique as a tool for the management of pancreatic ductal adenocarcinoma, it is still relatively unknown among radiologists. In this study, we sought to provide an overview of the main characteristics and eligibility criteria that must be considered for the indication of irreversible electroporation in cases of pancreatic ductal adenocarcinoma. [ABSTRACT FROM AUTHOR]

Posterior reversible encephalopathy syndrome (PRES) is a rare disease attributed to an increase in blood pressure that exceeds the autoregulatory capabilities of the cerebral vasculature, resulting in brain edema. Although PRES primarily affects adults, the pediatric population is also at risk. Radiologists must be aware of that risk because the imaging features on brain MRI are often atypical, especially in pediatric patients. Over a 6-year period, nine pediatric patients were diagnosed with PRES at our institution. Here, those patients are evaluated retrospectively regarding demographic characteristics, clinical profiles, imaging aspects, and outcomes. In this pictorial essay, we review the typical and atypical imaging findings of PRES in pediatric patients, demonstrating that it should be considered in patients with a clinical profile suggestive of the diagnosis, given that prompt, effective treatment is important for full recovery, thus avoiding major morbidity and mortality in such patients. [ABSTRACT FROM AUTHOR]

Brain death is the irreversible cessation of all brain function. Although protocols for its determination vary among countries, the concept of brain death is widely accepted, despite ethical and religious issues. The pathophysiology of brain death is related to hypoxia and ischemia in the setting of extensive brain injury. It is also related to the effects of brain edema, which increases intracranial pressure, leading to cerebral circulatory arrest. Although the diagnosis of brain death is based on clinical parameters, the use of neuroimaging to demonstrate diffuse brain injury as the cause of coma prior to definitive clinical examination is a prerequisite. Brain computed tomography (CT) and magnetic resonance imaging (MRI) demonstrate diffuse edema, as well as ventricular and sulcal effacement, together with brain herniation. Angiography (by CT or MRI) demonstrates the absence of intracranial arterial and venous flow. In some countries, electroencephalography, cerebral digital subtraction angiography, transcranial Doppler ultrasound, or scintigraphy/single-photon emission CT are currently used for the definitive diagnosis of brain death. Although the definition of brain death relies on clinical features, radiologists could play an important role in the early recognition of global hypoxic-ischemic injury and the absence of cerebral vascular perfusion. [ABSTRACT FROM AUTHOR]

Cardiac magnetic resonance imaging (MRI) is increasingly used in clinical practice due to its versatility. T1 mapping of the myocardium, a recently introduced MRI technique that is becoming available enables quantitative tissue characterization, overcoming some of the limitations of late enhancement. This promising technique has the ability to identify diffuse myocardial fibrosis and is beginning to be used in the diagnostic and prognostic assessment of several heart diseases.In this review, we start by explaining the physical principles of myocardial T1 mapping and possible confounding factors in its measurement. We then analyze the evidence supporting its potential usefulness as a complement to the existing cardiac MRI methods. Finally, we discuss the current limitations of T1 mapping and possible areas of future research. Resumo: A ressonância magnética (RM) cardíaca é um método de diagnóstico crescentemente utilizado pela sua versatilidade. O mapeamento do tempo T1 miocárdico, uma técnica de RM introduzida há alguns anos e que começa a estar clinicamente disponível, proporciona uma caracterização tecidular quantitativa, permitindo ultrapassar algumas limitações da avaliação de realce tardio. Esta técnica tem mostrado resultados promissores na identificação de fibrose difusa e começa a ser utilizada no diagnóstico e na avaliação prognóstica de várias patologias cardíacas. Neste artigo de revisão começamos por descrever os princípios das sequências de RM utilizadas no mapeamento miocárdico de T1, bem como os fatores que influenciam a sua medição. De seguida examinamos a evidência referente à sua utilidade potencial como complemento às técnicas de RM existentes em contextos clínicos diversos. Por fim, discutem-se as limitações atuais do mapeamento T1 e possíveis áreas de investigação futura.

Objective: To evaluate the role of magnetic resonance imaging (MRI) in the assessment of femoral and acetabular version in developmental dysplasia of the hip (DDH). Materials and Methods: This was a cross-sectional study of 20 consecutive patients with DDH (27 dysplastic hips) who were examined with MRI. In dysplastic and normal hips (DDH and comparison groups, respectively), we evaluated the following parameters: osseous acetabular anteversion (OAA); cartilaginous acetabular anteversion (CAA); femoral anteversion; osseous Mckibbin index (OMI); cartilaginous Mckibbin index (CMI); and the thickness of the anterior and posterior acetabular cartilage. Results: The OAA was significantly greater in the dysplastic hips. The CAA, femoral anteversion, OMI, and CMI did not differ significantly between the normal and dysplastic hips. In the DDH and comparison groups, the OAA was significantly lower than the CAA, the OMI was significantly lower than the CMI, and the posterior acetabular cartilage was significantly thicker than the anterior cartilage. Conclusion: Our findings confirm that MRI is a valuable tool for the assessment of femoral and acetabular version in DDH. Preoperative MRI evaluation has great potential to improve the planning of pelvic and femoral osteotomies. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the knees of individuals with renal failure who are on hemodialysis, using magnetic resonance imaging (MRI), comparing them with those of a group of individuals with normal renal function. Materials and Methods: This was a cross-sectional, observational, controlled study conducted between August 2018 and February 2020. The cases consisted of 15 patients who had been on hemodialysis for ≥ 5 years and did not have a quadriceps tendon rupture. The controls consisted of 15 individuals with normal renal function who were matched (1:1) to the cases for sex, age, and physical activity level. The subjects in both groups underwent MRI of the right knee only. Results: The mean ages of the cases and controls were 50 ± 15 years and 49 ± 14 years, respectively. The median time on hemodialysis was 11 years (range, 10-14 years). Serum levels of parathyroid hormone, ferritin, alkaline phosphatase, phosphorus, and creatinine were higher among the cases than among the controls, whereas serum albumin and hemoglobin were lower (p < 0.05 for all). The MRI study showed a hyperintense signal in the quadriceps tendon in 11 of the cases and in three of the controls (p = 0.009). Knee joint effusion was observed in nine of the cases and in three of the controls (p < 0.05). The thickness, length, and width of the tendon did not differ between the groups. A hyperintense signal in the tendon was not associated with the time on hemodialysis; nor with the levels of intact parathyroid hormone, hemoglobin, or alkaline phosphatase. Conclusion: Patients on chronic hemodialysis, even those without a tendon rupture, show a hyperintense signal in the quadriceps tendon on MRI. [ABSTRACT FROM AUTHOR]

Objective: To describe the alterations seen on magnetic resonance imaging (MRI) of the brain in newborns, correlating those alterations with the transfontanellar ultrasound (TFUS) findings, and to describe the main risk factors identified. Materials and Methods: We evaluated the examinations of 51 patients who were submitted to brain MRI with a neonatal protocol during hospitalization. We evaluated the MRI findings and correlated them with previous TFUS findings, using the last TFUS performed in order to minimize the risk of bias. Data were obtained from medical records, and the images were reviewed by a radiologist specializing in neuroimaging. Results: Of the 51 patients evaluated, 21 (41.2%) were extremely preterm infants and 22 (43.1%) were extremely-low-birth-weight infants. Alterations were seen on 16 (31.4%) of the TFUS examinations and on 30 (58.8%) of the brain MRI scans, the most common finding being germinal matrix hemorrhage. The positive and negative predictive values of TFUS in relation to MRI were 87% and 54%, respectively. Conclusion: Because TFUS proved to be capable of distinguishing mild and moderate (grade I and II) germinal matrix hemorrhage from the severe forms (grades III and IV), it can be considered a good tool for screening and follow-up, especially in infants with severe disease and risk factors. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the performance of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18FFDG PET/CT) in localizing epileptogenic zones, comparing 18F-FDG injection performed in the traditional interictal period with that performed near the time of a seizure. Materials and Methods: We evaluated patients with refractory epilepsy who underwent 18F-FDG PET/CT. The reference standards for localization of the epileptogenic zone were histopathology and follow-up examinations (in patients who underwent surgery) or serial electroencephalography (EEG) recordings, long-term video EEG, and magnetic resonance imaging (in patients who did not). The 18F-FDG injection was performed whether the patient had an epileptic seizure during the EEG monitoring period or not. The 18F-FDG PET/CT results were categorized as concordant or discordant with the reference standards. Results: Of the 110 patients evaluated, 10 were in a postictal group (FDG injection after a seizure) and 100 were in the interictal group. The 18F-FDG PET/CT was concordant with the reference standards in nine (90%) of the postictal group patients and in 60 (60%) of the interictal group patients. Among the nine postictal group patients in whom the results were concordant, the 18F-FDG PET/CT showed hypermetabolism and hypometabolism in the epileptogenic zone in four (44.4%) and five (55.6%), respectively. Conclusion: Our data indicate that 18F-FDG PET/CT is a helpful tool for localization of the epileptogenic zone and that EEG monitoring is an important means of correlating the findings. In addition, postictal 18F-FDG PET/CT is able to identify the epileptogenic zone by showing either hypometabolism or hypermetabolism. [ABSTRACT FROM AUTHOR]

Objetivo – Avaliar o contributo e eficiência das técnicas de perfusão por tomografia computorizada (TC) e ressonância magnética (RM) no diagnóstico do acidente vascular cerebral isquémico agudo. Métodos – Efetuou-se uma pesquisa bibliográfica eletrónica de que resultaram 2.224 artigos, sendo que 28 correspondiam aos critérios de inclusão por análise de definições (15 de TC, 11 de RM e 2 de TC e RM), eram estudos prospetivos, de adultos em risco de isquemia cerebral, com avaliação diagnóstica dos estudos de perfusão por TC (TCP) e RM (RMP) após acidente vascular cerebral. Compararam-se protocolos e níveis percentuais de exatidão, sensibilidade e especificidade através de análises métricas de frequência e expressão central. Resultados – Analisaram-se os dados correspondentes a parâmetros e técnicas de aquisição de imagens de perfusão quer em TC quer em RM. Verificou-se que a exatidão, sensibilidade e especificidade foi de 88,5%, 91,5% e 90,5% para RM e de 83%, 86% e 91,7% para TC, respetivamente. Conclusão – Apesar de a RM se manter como o método de imagem com maior valor clínico, a TC vem competir com a RM em situações de emergência médica, uma vez que a sua maior acessibilidade e rapidez permitem diminuir o tempo de espera entre o diagnóstico e a terapêutica.

In recent years, the development of new imaging techniques and scoring systems have improved the diagnosis and management of small renal masses. Imaging-based nephrometry scoring systems play an interesting role in the planning of nephron-sparing surgery, providing surgeons with the information necessary to determine the complexity of the renal mass, to deliver the appropriate postoperative care, and to predict adverse outcomes. The aim of this study was to review nephrometry scoring systems, evaluating their characteristics and the relationships among them. The urology and radiology communities should decide which nephrometry scoring system will prevail and be used in daily practice. [ABSTRACT FROM AUTHOR]

Ataxia is defined as a lack of coordination of voluntary movement, caused by a variety of factors. Ataxia can be classified by the age at onset and type (chronic or acute). The causative lesions involve the cerebellum and cerebellar connections. The correct, appropriate use of neuroimaging, particularly magnetic resonance imaging, can make the diagnosis relatively straightforward and facilitate implementation of the appropriate clinical management. The purpose of this pictorial essay is to describe the imaging findings of ataxia, based on cases obtained from the archives of a tertiary care hospital, with a review of the most important findings. We also discuss and review the imaging aspects of neoplastic diseases, malformations, degenerative diseases, and hereditary diseases related to ataxia. [ABSTRACT FROM AUTHOR]

Ataxia is defined as a lack of coordination of voluntary movement, caused by a variety of factors. Ataxia can be classified by the age at onset and type (chronic or acute). The causative lesions involve the cerebellum and cerebellar connections. The correct, appropriate use of neuroimaging, particularly magnetic resonance imaging, can make the diagnosis relatively accurate and facilitate implementation of the appropriate clinical management. The purpose of this pictorial essay is to describe the imaging findings of ataxia, based on cases obtained from the archives of a tertiary care hospital, with a review of the most important findings. We also review and discuss the imaging aspects of infectious, toxic, vascular, and inflammatory diseases. [ABSTRACT FROM AUTHOR]

Von Hippel-Lindau (VHL) disease is a rare, autosomal dominant inherited syndrome that affects the germline of the VHL gene, a tumor suppressor gene. VHL disease is characterized by the multisystemic development of a variety of benign and malignant tumors, especially in the central nervous system (CNS). Such tumors include retinal and CNS hemangioblastomas, as well as endolymphatic sac tumors. The various tumor sites are responsible for the diversity of signs and symptoms related to the disease. The mean age at symptom onset is 33 years. Despite medical advances, the average life expectancy of patients with VHL disease is 49 years. Imaging plays a pivotal role in the clinical diagnosis and is essential to the follow-up of patients with VHL disease. This pictorial essay describes characteristic CNS manifestations of VHL disease-related tumors that all radiology residents should be aware of. [ABSTRACT FROM AUTHOR]

Placenta accreta spectrum disorders are characterized by abnormal adhesion of the placenta that can be subdivided into three categories according to degree of invasion: placenta accreta (passing through the decidua basalis and adhering to the myometrium); placenta increta (penetrating the myometrium); and placenta percreta (invading the uterine serosa or adjacent tissues or organs). The incidence of placenta accreta has increased significantly in recent decades, mainly because of an increase in the rates of cesarean section, which is its main risk factor. Accurate prenatal identification makes it possible to institute the ideal treatment with a multidisciplinary team, significantly minimizing maternal morbidity and mortality. The examinations of choice are ultrasound and magnetic resonance imaging (MRI). When the ultrasound evaluation is inconclusive, as well as when the patient has risk factors for the condition or the placenta is in a posterior location, MRI is indicated. In cases of placental invasion of the adjacent pelvic organs, MRI is also preferable because it provides a broader field of view, which improves surgical planning. Numerous features of placenta accreta spectrum disorders are discernible on MRI, including dark intraplacental bands, uterine bulging, and heterogeneous placenta. Knowledge of these findings and the combination of two or more of them increase confidence in the diagnosis. [ABSTRACT FROM AUTHOR]

Objective: To assess the performance of the Ovarian-Adnexal Reporting and Data System Magnetic Resonance Imaging (O-RADS MRI) score in the evaluation of adnexal masses and to provide technical notes about its current MRI parameters and concepts. Materials and Methods: This was a prospective study of 226 patients with 287 adnexal masses (190 submitted to surgery or biopsy and 97 followed for at least one year). We calculated the sensitivity, specificity, positive predictive value, and negative predictive value for the O-RADS MRI score, using = 4 as the cutoff for malignancy. We performed a technical analysis of the main updates to the score, announced in September 2020 by the American College of Radiology, in comparison with the original (2013) version. Results: We found that an O-RADS MRI score of 4 or 5 was associated with malignancy of an adnexal mass, with a sensitivity of 91.11% (95% CI: 83.23-96.08), specificity of 94.92% (95% CI: 90.86-97.54), positive predictive value of 89.13% (95% CI: 81.71-93.77), negative predictive value of 95.90% (95% CI: 92.34-97.84), and overall accuracy of 93.73% (95% CI: 90.27-96.24). Conclusion: Our findings support the use of the O-RADS MRI score for evaluating adnexal masses, especially those considered indeterminate on ultrasound. The updates made recently to the O-RADS MRI score facilitate its interpretation and will allow its more widespread use, with no loss of diagnostic accuracy. [ABSTRACT FROM AUTHOR]

Resumo Apresentamos o relato de caso de uma paciente com mixoma valvar mitral infectado e uma revisão da literatura sobre o assunto. Uma mulher de 33 anos apresentou histórico de febre e dispneia com evolução de alguns dias. Na hospitalização, ela apresentava uma síndrome semelhante ao lúpus, com hemoculturas positivas para Haemophilus spp . O ecocardiograma revelou uma massa gigante envolvendo ambos os folhetos mitrais associada à regurgitação grave, necessitando de troca valvar mitral biológica. A microscopia revelou mixoma infectado e a paciente recebeu alta assintomática após o término da antibioticoterapia. Ela apresentou bons resultados no seguimento. Este é o sexto caso de mixoma valvar mitral infectado relatado na literatura e o terceiro caso de mixoma cardíaco infectado pelo grupo HACEK. Devido à alta incidência de eventos embólicos, a antibioticoterapia precoce aliada à pronta intervenção cirúrgica são decisivos para a redução da morbimortalidade. O tempo para o diagnóstico foi muito mais breve do que o geralmente relatado em casos de endocardite por HACEK. A troca valvar foi a intervenção mais comum e todos os pacientes em relatos de caso anteriores apresentaram bons resultados no seguimento.

Inherited neurometabolic disorders represent a diagnostic challenge, and an efficient classification system is needed in order to improve the understanding of these diseases. Although they constitute a group of rare diseases, they have a collective incidence of at least one case per 1,000 live births. Some inherited neurometabolic disorders are treatable. The clinical and radiological presentations are variable and sometimes overlap, depending on the stage of the disease. Therefore, a number of classification systems have been devised, some of which are difficult to apply in practice. The aim of this study was to illustrate a classification system for inherited neurometabolic disorders, based exclusively on radiological findings. This was a retrospective study of imaging examinations of the central nervous system, particularly of children, performed in a network of hospitals. All of the cases were studied by multidetector computed tomography, magnetic resonance imaging, or both, the images having been obtained by two neuroradiologists. We included only cases in which a definitive diagnosis was made. The classification system separates the relevant radiological findings into 10 categories. All of the cases studied presented at least one of those findings. In most of the cases, more than one finding was observed, which increased specificity and narrowed the differential diagnosis. Data from the literature and from this study demonstrate that it is possible to classify inherited neurometabolic disorders by their radiological aspects, which favors a definitive diagnosis. [ABSTRACT FROM AUTHOR]

Cystic echinococcosis (hydatid disease) is a zoonotic parasitic disease, caused by ingestion of Echinococcus granulosus eggs, that can result in cyst formation anywhere on the body. Hydatid disease is frequently seen in regions where there is human-animal contact and poor socioeconomic development. The prevalence of the disease ranges from 0 to 79 cases/100,000 population. Hydatid cysts are typically found in the liver and lungs, being less common in other parts of the body. Computed tomography or magnetic resonance imaging is often used in order to clarify the sites affected by a hydatid cyst, such as the cranial and thoracic regions, which also facilitates the surgical evaluation and minimizes complications. Although rare, hydatid cysts in atypical locations can provoke unusual complications, with unpredictable findings and symptoms. This essay discusses the radiological aspects of rare thoracic hydatid cysts. [ABSTRACT FROM AUTHOR]

Objective: To describe, assess the feasibility of, and quantify the long-term patency achieved with percutaneous transhepatic biliary dilation using the anastomotic biliary stricture (ABS) oversized balloon dilation technique as a single-step procedure for the treatment of benign anastomotic biliary strictures following hepatobiliary surgery. Materials and Methods: This was a retrospective, two-center study including 16 consecutive cases of symptomatic benign biliary-enteric strictures. After assessment of the diameter of the bile duct by computed tomography or magnetic resonance imaging, the strictures were dilated with oversized balloons (40-50% larger than the bile duct diameter) and an external biliary-enteric drain was placed. After drain removal, clinical symptoms and laboratory test results were evaluated every three months, whereas follow-up magnetic resonance imaging was performed at 30 days out and follow-up computed tomography was performed at 6 and 12 months out. Results: The mean follow-up time was 31.8 ± 8.15 months. Kaplan-Meier-estimated 1-, 2-, and 3-year patency rates were 88.2%, 82.4%, and 82.4%, respectively. There was one major complication--a small dehiscence of the anastomosis--which extended the catheter dwell time. Minor complications occurred in two cases--one small perihepatic hematoma and one segmental thrombosis of the left portal branch--neither of which required further intervention. Conclusion: The single-step ABS oversized balloon dilation technique is a feasible treatment for benign anastomotic biliaryenteric strictures. The technique appears to be associated with high rates of long-term clinical success and patency. [ABSTRACT FROM AUTHOR]

Introducción. Fetus in fetu es una rara entidad congénita en la cual se presenta un gemelo monocigótico que en la mayoría de los casos está incorporado en el abdomen del hermano. La presentación más frecuente es una masa retroperitoneal. La diferenciación diagnóstica entre fetus in fetu y teratoma es discutida. El objetivo de este trabajo es describir el caso de dos pacientes con fetus in fetu, mediante una revisión reducida de la literatura en sus hipótesis etiológicas y métodos diagnósticos. Reporte de casos. Se presentan 2 casos, el primer caso es un lactante menor con distensión abdominal persistente, en quien se palpó masa abdominal. El segundo caso es un recién nacido con diagnóstico prenatal de masa abdominal. Ambos casos presentan imágenes radiológicas que evidencian masa abdominal compatible con fetus in fetu, razón por la cual posteriormente fueron intervenidos quirúrgicamente para resección de la masa. Discusión. Es importante tener presente esta patología como diagnóstico diferencial de masa abdominal en los pacientes infantes, ya que el poder diferenciarlo de un teratoma maduro nos indicaría que se trata de una alteración del desarrollo embriológico y no de una patología tumoral. Para esto, son necesarios métodos imagenológicos y en algunos casos pruebas cromosómicas o histopatológicas, con el fin de esclarecer el diagnóstico del fetus in fetu. Conclusión. El fetus in fetu es una patología rara con pocos casos diagnosticados prenatalmente, la cual se diagnostica principalmente en la infancia. Las imágenes radiológicas y en algunos casos las pruebas cromosómicas o histopatológicas, son de gran importancia para el diagnóstico definitivo. Cómo citar. Lubinus F, Zuñiga-Hadechni E, López L, Rueda-Hernández, CA. Fetus in fetu, presentación de dos casos: diagnóstico diferencial y revisión de la literatura. MedUNAB. 2020;23(3):464-470. doi: doi.org/10.29375/01237047.3685 Introduction. Fetus in fetu is a rare congenital condition that has been defined as the presence of one monozygotic twin, in most cases, in the sibling’s abdomen. It is most frequently present as a retroperitoneal mass. The diagnostic difference between fetus in fetu and teratoma is discussed. This work’s objective is to describe the case of two patients with fetus in fetu through a reduced literature review in terms of etiologic hypotheses and diagnostic methods. Case Reports. Two cases are presented. The first case is that of an infant with persistent abdominal distension, in whom an abdominal mass was found by palpating. The second case is that of a newborn baby with a prenatal abdominal mass diagnosis. Both cases present X-ray images that demonstrate an abdominal mass compatible with fetus in fetu, reason why the patients were subsequently surgically intervened to remove the mass. Discussion. It is important to keep this pathology in mind as a differential diagnosis of abdominal masses in infant patients, since being able to differentiate it from a mature teratoma would indicate that the mass is an embryonic development alteration, not a tumor pathology. Imaging methods and, in some cases, chromosome or histopathological analyses, are necessary for this, in order to clarify the diagnosis of fetus in fetu. Conclusion. Fetus in fetu is a rare pathology with few cases diagnoses prenatally. It is mainly diagnosed during infancy. X-ray images and, in some cases, chromosome or histopathological analyses, are greatly important for definitive diagnoses. Cómo citar. Lubinus F, Zuñiga-Hadechni E, López L, Rueda-Hernández, CA. Fetus in fetu, presentación de dos casos: diagnóstico diferencial y revisión de la literatura. MedUNAB. 2020;23(3):464-470. doi: doi.org/10.29375/01237047.3685 Introdução. Fetus in fetu é uma entidade congénita rara em que existe um gémeo monozigótico que, na maioria dos casos, está incorporado no abdómen do irmão. A apresentação mais comum é uma massa retroperitoneal. A diferenciação diagnóstica entre fetus in fetu e teratoma é discutida. O objetivo deste trabalho é descrever o caso de dois pacientes com fetus in fetu, por meio de uma revisão reduzida da literatura sobre as suas hipóteses etiológicas e métodos de diagnóstico. Relato de casos. Dois casos são apresentados, o primeiro, é um bebê menor com distensão abdominal persistente, no qual foi sentida uma massa abdominal. O segundo caso é um recém-nascido com diagnóstico pré-natal de massa abdominal. Ambos os casos apresentam imagens radiológicas mostrando massa abdominal compatível com fetus in fetu, razão pela qual foram posteriormente operados para ressecção da massa. Discussão. É importante considerar esta patologia como diagnóstico diferencial da massa abdominal em pacientes infantis, uma vez que ser capaz de diferenciá-la de um teratoma maduro indicaria que se trata de uma alteração no desenvolvimento embriológico e não de uma patologia tumoral. Para isso, são necessários métodos de imagem e em alguns casos testes cromossômicos ou histopatológicos, a fim de esclarecer o diagnóstico do fetus in fetu. Conclusão. Fetus in fetu é uma patologia rara que é diagnosticado principalmente na infância, com poucos casos diagnosticados no pré-natal. As imagens radiológicas e, em alguns casos, os testes cromossômicos ou histopatológicos são de grande importância para o diagnóstico definitivo. Cómo citar. Lubinus F, Zuñiga-Hadechni E, López L, Rueda-Hernández, CA. Fetus in fetu, presentación de dos casos: diagnóstico diferencial y revisión de la literatura. MedUNAB. 2020;23(3):464-470. doi: doi.org/10.29375/01237047.3685

Background and objectives: To assess the agreement between the epidural depth measured from the surgical site with the epidural depths estimated with magnetic resonance imaging (MRI) and ultrasound scanning. Methods: Fifty patients of either sex, scheduled for L4‒5 lumbar disc surgery under general anesthesia were enrolled in this prospective observational study, and the results of 49 patients were analyzed. The actual epidural depth was measured from the surgical site with a sterile surgical scale. The MRI-derived epidural depth was measured from the MRI scan. The ultrasound estimated epidural depth was measured from the ultrasound image obtained just before surgery. Results: The mean epidural depth measured from the surgical site was 53.80 ± 7.67 mm, the mean MRI-derived epidural depth was 54.06 ± 7.36 mm, and the ultrasound-estimated epidural depth was 53.77 ± 7.94 mm. The correlation between the epidural depth measured from the surgical site and MRI-derived epidural depth was 0.989 (r2 = 0.979, p

Cerebral venous thrombosis (CVT) is an uncommon condition that is potentially reversible if properly diagnosed and promptly treated. Although CVT can occur at any age, it most commonly affects neonates and young adults. Clinical diagnosis is difficult because the clinical manifestations of CVT are nonspecific, including headache, seizures, decreased level of consciousness, and focal neurologic deficits. Therefore, imaging is crucial for the diagnosis. Radiologists should be able to identify the findings of CVT and to recognize potential imaging pitfalls that may lead to misdiagnosis. Thus, the appropriate treatment (anticoagulation therapy) can be started early, thereby avoiding complications and unfavorable outcomes. [ABSTRACT FROM AUTHOR]

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The diseases that affect the thalamus are heterogeneous in their etiologies, including infectious, inflammatory, vascular, toxicmetabolic, and neoplastic causes. It is often difficult to make the clinical differentiation between different entities. Within this context, computed tomography and magnetic resonance imaging have come to be of fundamental importance for defining the etiology and planning the treatment. In this pictorial essay, we will illustrate the main causes of diseases affecting the thalamus, discussing the possible differential diagnoses, as well as the most relevant imaging aspects. [ABSTRACT FROM AUTHOR]

Objective: To evaluate qualitative and quantitative magnetic resonance imaging (MRI) criteria for injury of the common peroneal nerve (CPN) in patients with acute or subacute injuries in the posterolateral corner (PLC) of the knee, as well as to evaluate the reproducibility of MRI evaluation of CPN alterations. Materials and Methods: This was a retrospective study of 38 consecutive patients submitted to MRI and diagnosed with acute or subacute injury to the PLC of the knee (patient group) and 38 patients with normal MRI results (control group). Two musculoskeletal radiologists (designated radiologist A and radiologist B, respectively) evaluated the images. Nerve injury was classified as neurapraxia, axonotmesis, or neurotmesis. Signal strength was measured at the CPN, the tibial nerve (TN), and a superficial vein (SV). The CPN/TN and CPN/SV signal ratios were calculated. The status of each PLC structure, including the popliteal tendon, arcuate ligament, lateral collateral ligament, and biceps tendon, was classified as normal, partially torn, or completely torn, as was that of the cruciate ligaments. For the semiquantitative analysis of interobserver agreement, the kappa statistic was calculated, whereas a receiver operating characteristic (ROC) curve was used for the quantitative analysis. Results: In the patient group, radiologist A found CPN abnormalities in 15 cases (39.4%)--neurapraxia in eight and axonotmesis in seven--whereas radiologist B found CPN abnormalities in 14 (36.8%)--neurapraxia in nine and axonotmesis in five. The kappa statistic showed excellent interobserver agreement. In the control group, the CPN/TN signal ratio ranged from 0.63 to 1.1 and the CPN/SV signal ratio ranged from 0.16 to 0.41, compared with 1.30-4.02 and 0.27-1.08, respectively, in the patient group. The ROC curve analysis demonstrated that the CPN/TN signal ratio at a cutoff value of 1.39 had high (93.3%) specificity for the identification of nerve damage, compared with 81.3% for the CPN/SV signal ratio at a cutoff value of 0.41. Conclusion: CPN alterations are common in patients with PLC injury detected on MRI, and the level of interobserver agreement for such alterations was excellent. Calculating the CPN/TN and CPN/SV signal ratios may increase diagnostic confidence. We recommend systematic analysis of the CPN in cases of PLC injury. [ABSTRACT FROM AUTHOR]

A dinâmica do spin é um dos problemas mais importantes da Física Moderna e seu estudo rendeu o prêmio Nobel de Física a vários cientistas importantes do século XX, cabendo destacar os nomes de Rabi, Bloch e Purcell. No entanto, dada a complexidade matemática associada ao problema do spin ½, cuja compreensão requer ao menos conhecimentos rudimentares de teoria de grupos e representações do grupo das rotações, normalmente não é abordado com a profundidade desejada em cursos de graduação. Dessa forma, o presente trabalho pretende suprir essa lacuna através da apresentação concisa e auto contida das ferramentas necessárias para a compreensão da dinâmica do spin e suas aplicações práticas. Sempre que possível, os eventos históricos mais importantes são mencionados. Os postulados fundamentais da mecânica quântica e da teoria do grupo das rotações são apresentados em um grau de profundidade suficiente para a compreensão dos principais conceitos associados ao spin. As equações de Bloch, não incluindo efeitos dissipativos, essenciais para a compreensão da ressonância magnética nuclear (RMN) são apresentadas a partir de primeiros princípios e resolvidas no caso do referencial girante.