Abstract Introduction Magnetic resonance imaging (MRI) T2* technique is used to assess iron overload in the heart, liver and pancreas of thalassaemic patients. Optimal iron chelation and expected tissue iron response rates remain under investigation. The objective of this study was to analyse serum ferritin and the iron concentration in the heart, liver and pancreas measured by MRI T2*/R2* during regular chelation therapy in a real-world cohort of patients with thalassemia. Methods We evaluated thalassaemic patients ≥ 7 years old undergoing chelation/transfusion therapy by MRI and assessed serum ferritin at baseline and follow-up from 2004-2011. Results We evaluated 136 patients, 92% major thalassaemic, with a median age of 18 years, and median baseline ferritin 2.033ng/ml (range: 59-14,123). Iron overload distribution was: liver (99%), pancreas (74%) and heart (36%). After a median of 1.2 years of follow-up, the iron overload in the myocardium reduced from 2,63 Fe mg/g to 2,05 (p 0.003). The optimal R2* pancreas cut-off was 148 Hertz, achieving 78% sensitivity and 73% specificity. However, when combining the R2* pancreas cut off ≤ 50 Hertz and a ferritin ≤ 1222 ng/ml, we could reach a negative predictive value (NPV) of 98% for cardiac siderosis. Only 28% were undergoing combined chelation at baseline assessment, which increased up to 50% on follow up evaluation. Conclusions Chelation therapy significantly reduced cardiac siderosis in thalassaemic patients. In patients with moderate/severe liver iron concentration undergoing chelation therapy, ferritin levels and myocardium iron improved earlier than the liver siderosis.

Abstract Prostate-specific membrane antigen (PSMA) is a transmembrane protein expressed in normal prostate cells and overexpressed in prostate cancer. Consequently, it is an important tool in the evaluation of prostate cancer, including the staging of high-risk patients and the assessment of biochemical recurrence. Despite the “specific” designation, benign musculoskeletal conditions, such as fractures, osteodegenerative changes, and fibrous dysplasia, can also show PSMA uptake, which can lead to misinterpretation of the imaging findings. Therefore, radiologists must be aware of these potential pitfalls, understand their causes, and fully analyze their morphologic features on unfused computed tomography (CT) and magnetic resonance imaging scans to correctly interpret the examination. In this pictorial essay, we review the basic characteristics of the 68Ga-PSMA positron-emission tomography/CT (PET/CT) radiotracer, discuss potential causes of false-positive findings on 68Ga-PSMA PET/CT in the musculoskeletal system, and illustrate the corresponding imaging findings.

Resumo O antígeno de membrana próstata específico (PSMA) é uma proteína transmembrana que apresenta expressão em células prostáticas normais e superexpressão em neoplasia da próstata. Dessa forma, é uma importante ferramenta na avaliação da neoplasia prostática, de utilidade no estadiamento de pacientes de alto risco e na análise de recorrência bioquímica. Apesar do termo “específico”, condições musculoesqueléticas benignas podem demonstrar captação de PSMA, como fraturas, alterações osteodegenerativas e displasia fibrosa, podendo levar a uma avaliação equivocada dos achados de imagem. Assim, o radiologista deve conhecer esses potenciais pitfalls, compreender suas causas e analisar as características morfológicas nas imagens não fundidas de TC e RM para interpretar corretamente o exame. Neste ensaio iconográfico, revisaremos as características básicas do radiofármaco 68Ga-PSMA PET/CT, discutiremos possíveis causas de resultados falso-positivos na 68Ga-PSMA PET/CT no sistema musculoesquelético e ilustraremos os achados de imagem correspondentes.

ABSTRACT Objective: To compare enhancement patterns of typical adrenal adenomas, lipid-poor adenomas, and non-adenomas on magnetic resonance imaging (MRI). Materials and Methods: Evaluation of adrenal nodules larger than 1.0 cm, with at least 2-year follow-up, evaluated on MRI in January 2007 and December 2016. Two different protocols were included - upper abdomen MRI (delayed phase after 3 minutes) and abdomen and pelvis MRI (delayed phase after 7 minutes) – and nodules were divided in typical adenomas (characterized on out-of-phase MRI sequence), lipid-poor adenomas (based on follow-up imaging stability) and non-adenomas (based on pathological finding or follow-up imaging). T2-weighted and enhancement features were analyzed (absolute and relative washout and enhancement curve pattern), similarly to classic computed tomography equations. Results: Final cohort was composed of 123 nodules in 116 patients (mean diameter of 1.8 cm and mean follow up time of 4 years and 3 months). Of them, 98 (79%) nodules had features of typical adenomas by quantitative chemical shift imaging, and demonstrated type 3 curve pattern in 77%, mean absolute and relative washout of 29% and 16%, respectively. Size, oncologic history and T2-weighted features showed statistically significant differences among groups. Also, a threshold greater than 11.75% for absolute washout on MRI achieved sensitivity of 71.4% and specificity of 70.0%, in differentiating typical adenomas from non-adenomas. Conclusion: Calculating absolute washout of adrenal nodules on MRI may help identifying proportion of non-adenomas.

ABSTRACT Objective To evaluate the predictive value of positron emission computed tomography or magnetic resonance (PET-CT and PET-MRI) using gallium-68-labeled prostate-specific membrane antigen (68Ga-PSMA) in lymph node involvement in prostate cancer. Methods A retrospective study comprising 91 patients diagnosed with prostate cancer between 2016 to 2020, who underwent 68Ga-PSMA PET-CT or PET-MRI for staging before prostatectomy. The patients were divided into Group 1, with 65 patients with satisfactory pathological lymph node analysis, and Group 2, with 91 patients representing the sum of patients with pathological lymph node analysis and those with postoperative prostate-specific antigen within 60 days after surgery. Receiver Operating Characteristic curves were used to assess accuracy of predictive capacity of imaging exams for lymph node involvement. Results Regarding local clinical staging, the groups showed similar results, and 50% were classified as staging T2a. The accuracy of 68Ga-PSMA PET-CT for prostate cancer lymph node staging was 86.5% (95%CI 0.74-0.94; p=0.06), with a sensitivity of 58.3% and specificity of 95%. The accuracy of 68Ga-PSMA PET-MRI was 84.6% (95%CI 0.69-0.94; p=0.09), with a sensitivity of 40% and specificity of 100%. Considering both 68Ga-PSMA PET-CT and PET-MRI, the accuracy was 85.7% (95%CI 0.76-0.92; p=0.015), with sensitivity of 50% and specificity of 97%. Conclusion The imaging tests 68Ga-PSMA PET-CT and PET-MRI were highly accurate to detect preoperative lymph node involvement, and could be useful tools to indicate the need for extended lymph node dissection during radical prostatectomy.

ABSTRACT Objective To evaluate whether the presence of a hypointense signal at T2-weighted imaging in a solid ovarian lesion on magnetic resonance imaging is a predictor of stability and benignity. Methods This is a single center study, prospectively read with retrospective acquired data. The database was searched for patients who underwent magnetic resonance imaging between January 2008 and October 2019 and whose reports mentioned solid ovarian lesions with low signal on T2-weighted imaging. A total of 47 nodules were included. A radiologist who was blinded to the clinical indication for magnetic resonance imaging and original reports evaluated the cases. Objective and subjective criteria of ovarian lesions in magnetic resonance imaging were evaluated. Results Thirty-five nodules were considered benign/stable and 12 were considered non-stable. The analysis showed that the non-stable lesions showed statistically more hyperintensity at T1-weighted imaging compared to the stable lesions. Conclusion T2-weighted imaging hypointensity can be considered a predictor of stability in solid ovarian lesions when associated with iso/hypointensity in T1-weighted imaging.

Abstract Objective To evaluate whether there is a significant difference in somatostatin analog uptake in meningiomas treated or not with radiation therapy. Methods A cross-sectional study was performed comparing measurements of somatostatin analog (68Ga-DOTATATE) uptake in two independent groups of ten patients each - one consisting of patients with meningiomas previously treated with radiation therapy and another comprising patients who had never been submitted to radiation therapy. All patients underwent PET/CT and MRI scans in an interval shorter than 24 hours between exams. Results A total of 32 meningiomas from 20 patients were analyzed, all presenting significant somatostatin analog uptake in different degrees. The uptake levels of somatostatin analog were similar between the lesions treated or not with radiation therapy, and the mean values of SUVmax were 27.62 and 24.82, respectively (p=0.722). For SUVmean, the values were 16.20 and 14.82, respectively (p=0.822). Conclusion Comparative analysis between the groups showed no significant differences in degree of somatostatin analog uptake in successfully irradiated and non-irradiated meningiomas.

ABSTRACT Objective To identify magnetic resonance imaging findings of the prostate in young adults, including symptomatic and asymptomatic patients. The aim of this study is to evaluate the main aspects of prostate imaging in young patients. Methods A total of 102 patients under 40 years of age, who underwent prostate magnetic resonance imaging between January 2016 and January 2019, were included in this study. The patients were divided into two groups: symptomatic for prostatitis (Group 1) and asymptomatic (Group 2). Magnetic resonance imaging scans were anonymized and interpreted by a radiologist blinded for clinical information. The study evaluated peripheral zone signal in T2-weighted sequences, diffusion and apparent diffusion coefficient map; peripheral zone enhancement pattern; seminal vesicles and periprostatic fat. Results All evaluated criteria did not present statistically significant differences between the two groups. The most common pattern was heterogeneous hyposignal on T2 (57.9% in Group 1 and 57.8% in Group 2; p=0.506), mild diffuse / wedge-shaped areas of hypointensity on apparent diffusion coefficient map (61.4% in Group 1 and 64.4% in Group 2; p=0.931) and early post-contrast enhancement (73.7% in Group 1 and 68.9% in Group 2, p=0719). Conclusion The magnetic resonance imaging aspect of young patients showed no differences between symptomatic and asymptomatic patients.

RESUMO Objetivo Avaliar a sequência de ressonância magnética blood-oxygen-level-dependent (BOLD) realizada em um equipamento 3 Tesla para medir a biodisponibilidade do oxigênio do tecido pelo valor de R2* na diferenciação de necrose tubular aguda e rejeição aguda, comparando à biópsia renal (padrão-ouro). Métodos Estudo unicêntrico, prospectivo, com pacientes submetidos a transplante renal de 2013 a 2014, que desenvolveram disfunção do enxerto menos de 4 semanas após o transplante. Todos os pacientes foram submetidos à ressonância magnética abdominal 3 Tesla com o mesmo protocolo, seguida de duas sequências BOLD e biópsia renal. Resultados Foram incluídos 12 homens (68,75%) e três mulheres (31,25%). Foram realizadas 19 biópsias renais percutâneas (quatro pacientes necessitaram de segunda biópsia devido à alteração nos achados clínicos). Os resultados histopatológicos incluíram dez casos de necrose tubular aguda, quatro de rejeição aguda e cinco casos de outros diagnósticos (miscelânea). A comparação entre os quatro grupos de interesse não mostrou diferenças significativas em relação ao R2* no córtex (p=0,177). Quanto ao R2* da medula, observaram-se diferenças significativas (p=0,033), com miscelânea e necrose tubular aguda apresentando valores mais baixos quando comparados aos demais. Conclusão A ressonância magnética BOLD 3 Tesla é uma técnica viável que indiretamente utiliza a concentração de oxigênio no tecido em enxertos renais e pode ser usada para a diferenciação entre rejeição aguda e necrose tubular aguda.

ABSTRACT Objective To evaluate the ability of blood-oxygen-level-dependent (BOLD) magnetic resonance imaging at 3 Tesla to measure tissue oxygen bioavailability based on R2* values, and to differentiate between acute tubular necrosis and acute rejection compared to renal biopsy (gold standard). Methods A prospective, single-center study, with patients submitted to renal transplantation between 2013 and 2014, who developed graft dysfunction less than 4 weeks after transplantation. All patients were submitted to abdominal magnetic resonance imaging at 3 Tesla using the same protocol, followed by two BOLD sequences and kidney biopsy. Results Twelve male (68.75%) and three female (31.25%) patients were included. A total of 19 percutaneous renal biopsies were performed (four patients required a second biopsy due to changes in clinical findings). Pathological findings revealed ten cases of acute tubular necrosis, four cases of acute rejection, and five cases with other (miscellaneous) diagnoses. Comparison between the four groups of interest failed to reveal significant differences (p=0.177) in cortical R2* values, whereas medullary R2* values differed significantly (p=0.033), with lower values in the miscellaneous diagnoses and the acute tubular necrosis group. Conclusion BOLD magnetic resonance imaging at 3 Tesla is a feasible technique that uses indirect tissue oxygen level measurements to differentiate between acute rejection and acute tubular necrosis in renal grafts.

Resumo Objetivo: Avaliar aspectos práticos do uso de agentes de contraste à base de gadolínio (gadolinium-based contrast agents - GBCAs) por médicos especialistas em radiologia. Materiais e Métodos: Dez radiologistas de diferentes regiões do Brasil foram convidados a participar de um painel Delphi com perguntas sobre o uso de GBCAs lineares e macrocíclicos (1,0 e 0,5 M), em termos de dosagem, volume injetado e preocupações relacionadas à segurança. Resultados: A taxa de resposta foi de 100% para todas as perguntas. GBCAs são seguros em relação a reações adversas agudas, e os casos de fibrose nefrogênica sistêmica são raros. O depósito de gadolínio no cérebro e em outros tecidos é uma preocupação de todo o painel. Agentes macrocíclicos são preferíveis aos lineares. Um volume menor que 0,1 mL/kg injetado de contraste macrocíclico 1,0 M poderia oferecer imagem com boa qualidade e benefício adicional em longo prazo, entretanto, não há evidências publicadas que apóiem tal recomendação. A maioria prefere não administrar GBCA em gestantes. Conclusão: É importante considerar as características de deposição e minimizar potenciais riscos ao se escolher um GBCA. Ações de educação médica são necessárias para a conscientização dos potenciais riscos da presença de gadolínio em longo prazo e evitar a sobre-exposição ao agente de contraste.

Abstract Objective: To assess the practical aspects of the use of various gadolinium-based contrast agents (GBCAs) by radiologists. Materials and Methods: Ten experienced radiologists from different regions of Brazil participated in a Delphi panel querying their use of various GBCAs, including linear and macrocyclic classes (1.0 and 0.5 M), in terms of the choice of agent, volume and dosage of the agents, and associated safety concerns. Results: The response rate was 100% for all questions. GBCAs are safe in terms of acute adverse reactions, and nephrogenic systemic fibrosis is rare. The deposition of gadolinium in the brain and other tissues is a concern among the experts. Macrocyclic agents are preferable to linear agents; an injection volume below 0.1 mL/kg of a 1.0 M agent could result in good-quality images with additional long-term safety, but there is no published evidence to support this recommendation. The majority of experts preferred not to administer GBCAs to pregnant patients. Conclusion: When choosing a GBCA, it is important to consider the characteristics of the gadolinium deposition in patient tissues and minimize potential risks. Furthermore, medical education programs are needed to increase the awareness of the potential risks of gadolinium deposition and thus avoid instances of overexposure to the contrast agent.

RESUMO Objetivo: Avaliar os fatores anatômicos e a experiência do radiologista na detecção de massas renais sólidas na ultrassonografia. Métodos: Buscamos massas renais sólidas diagnosticadas em imagens seccionais, de 2007 a 2017, que também tivessem ultrassonografia prévia nos últimos 6 meses. As seguintes características foram avaliadas: tamanho do nódulo, lateralidade, localização e padrão de crescimento, índice de massa corporal do paciente e experiência do radiologista em ultrassonografia. Nos casos com ressecção cirúrgica, os laudos de patologia foram analisados. O teste t não pareado e o teste χ2 foram utilizados para avaliar as diferenças entre os subgrupos, usando R-statistics. A significância estatística foi estabelecida em p<0,05. Resultados: A pesquisa inicial de nódulos renais achados em imagens seccionais resultou em 428 lesões, com 266 exclusões. A coorte final incluiu 162 lesões e, destas, 108 (67%) foram detectadas corretamente na ultrassonografia (Grupo 1), e 54 (33%) não foram identificadas (Grupo 2). A comparação dos Grupos 1 e 2 mostrou índice de massa corporal (27,7 versus 27,1; p=0,496), tamanho (2,58cm versus 1,74cm; p=0,003), lateralidade (54% versus 59% no lado direito; p=0,832), localização (27% versus 22% no polo superior; p=0,869), padrão de crescimento (25% versus 28% endofítico; p=0,131) e experiência do radiologista (p=0,300). A histologia disponível para o Grupo 1 foi carcinoma renal de células claras (n=11), papilar (n=15), cromófobo (n=2), oncocitoma (n=1), e, para o Grupo 2, carcinoma renal de células claras (n=7), papilar (n=5), oncocitoma (n=2), angiomiolipoma, cromófobo e pielonefrite intersticial (n=1, cada). Conclusão: O tamanho foi o único parâmetro significativo relacionado à detecção de nódulos renais no ultrassom.

ABSTRACT Objective: To evaluate anatomic factors and radiologist's experience in the detection of solid renal masses on ultrasonography. Methods: We searched for solid renal masses diagnosed on cross-sectional imaging from 2007 to 2017 that also had previous ultrasonography from the past 6 months. The following features were evaluated: nodule size, laterality, location and growth pattern, patient body mass index and radiologist's experience in ultrasound. In surgically resected cases, pathologic reports were evaluated. Unpaired t test and χ2 test were used to evaluate differences among subgroups, using R-statistics. Statistical significance was set at p<0.05. Results: The initial search of renal nodules on cross-sectional imaging resulted in 428 lesions and 266 lesions were excluded. Final cohort included 162 lesions and, of those, 108 (67%) were correctly detected on ultrasonography (Group 1) and 54 (33%) were missed (Group 2). Comparison of Groups 1 and 2 were as follows, respectively: body mass index (27.7 versus 27.1; p=0.496), size (2.58cm versus 1.74cm; p=0.003), laterality (54% versus 59% right sided; p=0.832), location (27% versus 22% upper pole; p=0.869), growth pattern (25% versus 28% endophytic; p=0.131) and radiologist's experience (p=0.300). From surgically resected cases, histology available for Group 1 was clear cell (n=11), papillary (n=15), chromophobe (n=2) renal cell carcinoma, oncocytoma (n=1), and, for Group 2, clear cell (n=7), papillary (n=5) renal cell carcinoma, oncocytoma (n=2), angiomyolipoma, chromophobe renal cell carcinoma, and interstitial pyelonephritis (n=1, each). Conclusion: Size was the only significant parameter related to renal nodule detection on ultrasound.

RESUMO A COVID-19 foi declarada uma pandemia no início de 2020. Constatou-se, inicialmente, que as principais manifestações desse novo vírus ocorrem por meio de sintomas respiratórios e constitucionais. A tomografia do tórax foi eleita o exame de imagem para avaliar a extensão do comprometimento pulmonar e como um fator preditivo do prognóstico para a doença. No entanto, à medida que novos estudos são produzidos, o envolvimento gastrointestinal da COVID-19 torna-se mais evidente, com relatos de pacientes que manifestaram principalmente ou apenas sintomas gastrointestinais no decorrer da doença. Em alguns casos, a investigação inicial é realizada no pronto-socorro, com tomografia computadorizada do abdome. Relatamos uma série de casos de dez pacientes que compareceram ao serviço de emergência da instituição com uma queixa principal gastrointestinal e foram submetidos inicialmente a uma tomografia computadorizada de abdome como primeira investigação. Embora a maioria dos pacientes não tenha apresentado alterações significativas nas imagens abdominais, eles apresentaram achados pulmonares visualizados nas bases pulmonares, que depois foram caracterizadas como achados pulmonares típicos de COVID-19 nas tomografias de tórax subsequentes. Apenas um paciente apresentou achados atípicos para COVID-19 na tomografia. Todos os pacientes tiveram reação em cadeia da polimerase em tempo real positiva para o novo coronavírus. É muito importante alertar os radiologistas, principalmente os radiologistas abdominais, da possibilidade de sintomas gastrointestinais isolados no contexto da COVID-19. Além disso, deve ser um hábito para todos os radiologistas avaliar as bases pulmonares nas tomografias de abdome, local comumente afetado pela COVID-19.

ABSTRACT The COVID-19 became a pandemic in early 2020. It was found, at first, that the main manifestations of this new virus occur through respiratory and constitutional symptoms. Therefore, chest tomography was elected as the best imaging test to assess the extent of pulmonary involvement and as a good prognostic predictor for the disease. However, as new studies were produced, the gastrointestinal involvement of COVID-19 becomes more evident, with reports from patients who manifested mainly or only gastrointestinal symptoms in the course of the disease. Thus, in some cases, the initial investigation is carried out at the emergency department with an abdominal computed tomography. We report a case series of ten patients who came to the emergency department of our institution with a chief gastrointestinal complaint, and were initially submitted to an abdominal computed tomography as the first investigation. Although most of the patients did not have significant changes in the abdominal images, most reported patients had pulmonary findings visualized at the lung bases, which were later designated as typical COVID-19 pulmonary findings on chest computed tomography. Only one patient had atypical COVID-19 lung changes on chest computed tomography. All patients had a positive real-time polymerase chain reaction for COVID-19. It is imperative to alert radiologists, especially abdominal radiologists, with the possibility of COVID-19 isolated gastrointestinal symptoms. Besides, it must become a habit to radiologists to assess the pulmonary basis on abdominal scans, a site commonly affected by the new coronavirus.

RESUMO Objetivo Avaliar a acurácia da ressonância magnética multiparamétrica da próstata para estimativa do volume da glândula, comparando seus resultados com a ultrassonografia transretal e correlacionando com o volume obtido da peça cirúrgica. Métodos Estudo retrospectivo incluindo 85 pacientes submetidos à ressonância magnética e, posteriormente, à ultrassonografia transretal (para orientação de biópsia com fusão de imagens) e, a seguir, à prostatectomia radical. As dimensões prostáticas foram obtidas na ressonância a partir das imagens nos planos axial e sagital em sequências ponderadas em T2 e, assim como na ultrassonografia, o volume foi calculado a partir do método da elipsoide. Os valores foram comparados com o peso prostático pós-cirúrgico. O intervalo máximo entre a ressonância e ultrassonografia e prostatectomia foi de 6 meses. Resultados O volume prostático obtido por ressonância magnética foi de 18 a 157cm3(média de 49,9cm3); pela ultrassonografia transretal, foi de 22 a 165cm3(média de 54,9cm3); e o peso da peça cirúrgica foi de 20 a 154g (média de 48,6g), sem diferenças estatísticas. A partir do valor obtido por esses métodos de imagem, provou-se que o volume prostático obtido aproximou-se bastante do peso real da próstata, com discreta maior precisão das medidas obtidas por ressonância magnética multiparamétrica. Conclusão As medidas do volume prostático adquiridas pela ressonância magnética e pela ultrassonografia transretal são semelhantes entre si, com excelente concordância com os pesos reais das próstatas obtidos das peças cirúrgicas. A avaliação desse dado, a partir da ressonância, método cada vez mais utilizado na prática clínica, permite o adequado planejamento terapêutico e o controle dos pacientes.

ABSTRACT Objective To assess accuracy of multiparametric magnetic resonance of the prostate to estimate gland volume, comparing the results with transrectal ultrasound and surgical specimen. Methods A retrospective study of 85 patients who underwent multiparametric magnetic resonance and transrectal ultrasound (for fusion image-guided biopsy) before radical prostatectomy. Prostate measurements were obtained from magnetic resonance axial and sagittal T2-weighted images and ultrasound; the prostate volume was determined using the ellipsoid formula. The results were compared with the surgical specimen weight. Maximum interval between multiparametric magnetic resonance imaging, transrectal ultrasound, and prostatectomy was 6 months. Results The prostate volume measured by multiparametric magnetic resonance imaging was 18-157cm3 (mean of 49.9cm3) and by transrectal ultrasound, 22-165cm3 (mean of 54.9cm3); the surgical specimen weight was 20-154g (mean of 48.6g), with no statistical differences. Based on the values obtained from imaging examinations, the prostate volume obtained was very close to the real prostatic weight, and the measures by multiparametric magnetic resonance were slightly more precise. Conclusion Prostate volume measured by multiparametric magnetic resonance imaging and transrectal ultrasound showed similar values, and excellent agreement with real prostate weight of the surgical specimens. Prostate volume measured by magnetic resonance has been increasingly used in the clinical practice, and its value enables appropriate therapeutic planning and control of patients.

Resumo Objetivo: Avaliar a correlação de critérios morfológicos do apêndice cecal por tomografia computadorizada (TC) e o risco de apendicite aguda. Materiais e Métodos: Casos foram definidos como apendicite aguda confirmada cirurgicamente que tiveram pelo menos dois exames de TC: um no diagnóstico de apendicite aguda e outro no mínimo um mês antes. O grupo controle foi definido como pacientes emergenciais com dor abdominal com TC de abdome excluindo apendicite aguda e com TC prévia pelo menos um mês antes. Resultados: 100 casos e 100 controles foram selecionados. A comparação das variáveis dos casos e controles revelou: diâmetro transverso médio de 0,6 cm (faixa: 0,4-1,0 cm) versus 0,6 (faixa: 0,6-0,8 cm) (p = 0,37); comprimento médio de 6,6 cm (faixa: 3,5-9,7 cm) versus 6,6 cm (faixa: 4,5-8,3 cm) (p = 0,87); ângulo médio de 100° (faixa: 23-178°) versus 86° (faixa: 43-160°) (p = 0,01); orientação descendente em 56% versus 45% (p = 0,2); ausência de gás em 69% versus 77% (p = 0,34) e presença de apendicólito em 17% versus 8% (p = 0,08). Conclusão: Fatores obstrutivos hipotéticos do apêndice cecal na TC não foram associados a apendicite aguda. Isso sugere que outros fatores diferentes de obstrução mecânica podem estar implicados na gênese da apendicite aguda.

Abstract Objective: To evaluate the correlation of morphological criteria of the cecal appendix using computed tomography (CT) and the possible risk of developing acute appendicitis. Materials and Methods: Cases were defined as patients with surgically confirmed acute appendicitis who had undergone CT at least twice: at diagnosis and at least one month prior. Controls were defined as emergency patients with abdominal pain who had undergone abdominal CT that excluded acute appendicitis and had also undergone CT at least one month before. Results: 100 cases and 100 controls were selected for inclusion in the final analysis. Comparisons between the cases and controls revealed the following: mean transverse diameter of 0.6 cm (range, 0.4-1.0 cm) versus 0.6 cm (range, 0.6-0.8 cm; p = 0.37); mean length of 6.6 cm (range, 3.5-9.7 cm) versus 6.6 cm (range, 4.5-8.3 cm; p = 0.87); mean angle of 100° (range, 23-178°) versus 86° (range, 43-160°; p = 0.01); vertical descending orientation in 56% versus 45% (p = 0.2); absence of gas in 69% versus 77% (p = 0.34); and presence of an appendicolith in 17% versus 8% (p = 0.08). Conclusion: Hypothetical risk factors for obstruction of the vermiform appendix detected on CT were not associated with acute appendicitis. That suggests that factors other than those related to mechanical obstruction are implicated in the pathogenesis of acute appendicitis.