Reliability of synthetic diffusion-weighted imaging with a high b-value for paediatric abdominal MRI.

AIM: To evaluate the reliability of synthetic diffusion-weighted imaging (DWI) using a high b-value in comparison to conventional DWI for paediatric abdominal MRI. MATERIALS AND METHODS: Paediatric patients (<19 years old) who underwent liver or pancreatobiliary MRI with DWI using 10 b-values (b = 0, 25, 50, 75, 100, 200, 400, 600, 800, 1,500 s/mm2) from March to October 2021 were included in this retrospective study. Using the software, synthetic DWI using b = 1,500 s/mm2 was generated automatically by selecting the b-value required as output. Conventional and synthetic DWI values for b = 1,500 s/mm2 were measured at the liver, spleen, paraspinal muscle, and mass lesions, if present, and apparent diffusion coefficient (ADC) values were calculated using the mono-exponential model. Intraclass correlation coefficients (ICCs) were calculated to assess the reliability of conventional and synthetic DWI and ADC values with b = 1,500 s/mm2. RESULTS: Thirty paediatric patients (M:F = 22:8, mean 10.8 ± 3.1 years old) were included and four had tumours on abdominal MRI. ICC values were 0.906-0.995 between conventional and synthetic DWI and ADC with b = 1,500 s/mm2 in the liver, spleen and muscle. For mass lesions, ICC values were 0.997-0.999 for both synthetic DWI and ADC images. CONCLUSIONS: Synthetic DWI and ADC values obtained using a high b-value showed excellent agreement with conventional DWI for the liver, spleen, muscle, and mass in paediatric MRI.

Transanal total mesorectal excision for locally advanced middle-low rectal cancers.

BACKGROUND: This study investigated the results of transanal total mesorectal excision (TaTME) combined with laparoscopy for locally advanced mid-low rectal cancer. METHODS: Patients with mid-low locally advanced rectal cancer (T3 category or above and/or N+) who underwent rectal resection with TaTME technique were enrolled prospectively. Patients who had distant metastasis, multiple malignancies, intestinal obstruction or perforation, or a clinical complete response to chemoradiotherapy were excluded. Postoperative results, including morbidity, circumferential resection margin (CRM) assessment, short-term survival and functional outcomes, were analysed. RESULTS: Thirty-eight patients, with 25 mid and 13 low rectal tumours, who had elective resection by TaTME from March 2015 to September 2018 were included. There were 25 men and 13 women. Mean(s.d.) age was 58·2(16·4) years and mean(s.d.) BMI was 24·2(2·5) kg/m2 . Tumours were 3-9 cm from the anal verge. Mean(s.d.) duration of surgery was 210(42) min. All patients had hand-sewn anastomoses and protective ileostomies. There were no conversions, abdominal perineal resections or postoperative deaths. Four patients had a complication, including three presacral abscesses, all managed by transanastomotic drainage. At 3 months after ileostomy closure, all patients had perfect continence. Apart from a greater tumour diameter in patients with low rectal cancers (6·0 cm versus 4·6 cm in those with mid rectal tumours; P = 0·035), clinical features were similar in the two groups. CRM positivity was greater for low than for mid rectal tumours (3 of 13 versus 0 of 25 respectively; P = 0·034), and more patients with a low tumour had TME grade 2 (4 of 13 versus 1 of 25; P = 0·038). There was no difference in oncological outcomes at 17 months. CONCLUSION: Although this study cohort was small, special attention should be paid to bulky low rectal tumours to reduce the rate of CRM positivity.

ANTECEDENTES: La escisión total del mesorrecto transanal (transanal total mesorectal excision, TaTME) combinada con la laparoscopia convencional se ha descrito como un procedimiento prometedor para el tratamiento del cáncer de recto medio-inferior localmente avanzado. El objetivo de este estudio fue investigar los resultados de TaTME combinados con la laparoscopia para el cáncer de recto medio-inferior localmente avanzado. MÉTODOS: Se incluyeron de forma prospectiva los pacientes con cáncer de recto medio-inferior localmente avanzado (≥ T3 y/o N+) a los que se realizó una resección anterior de recto con la técnica TaTME. Se excluyeron aquellos pacientes con metástasis a distancia, neoplasias múltiples, obstrucción intestinal o perforación y aquellos que presentaron una respuesta clínica completa después de la quimiorradioterapia. Los pacientes recibieron tratamiento neoadyuvante de acuerdo con las guías de práctica clínica internacionales. Se analizaron los resultados postoperatorios entre los que se incluyen la morbilidad, la evaluación del margen de resección circunferencial (circumferential resection margin, CRM) y la supervivencia a corto plazo junto con los resultados funcionales. RESULTADOS: Se seleccionaron 38 pacientes, 25 con el tumor en el recto medio y 13 con el tumor en el recto inferior que se sometieron a una resección anterior de recto electiva por TaTME desde marzo de 2015 hasta septiembre de 2018. Las localizaciones de los tumores oscilaron entre 3 y 9 cm desde el margen anal. La relación varón/mujer fue de 1,93, la edad media fue de 58,2 ± 16,4 años y el IMC medio de 24,2 ± 2,5 kg/m2 . El tiempo medio operatorio fue de 210 ± 42 minutos. En la todos los pacientes se realizó una anastomosis manual y una ileostomía de protección. No se registró ninguna conversión, ninguna amputación abdomino-perineal y ninguna muerte postoperatoria en toda la cohorte. Cuatro pacientes (10,5%) presentaron alguna complicación, incluidos tres abscesos presacros (7,9%), todos tratados mediante drenaje a través de la anastomosis. La continencia a los 3 meses del cierre de la ileostomía fue grado I según la clasificación de Horgan en todos los pacientes. Las características clínicas fueron similares en los cánceres de recto medio e inferior, sin embargo, este último grupo presentó un diámetro tumoral medio mayor en la estadificación clínica (4,8 en el cáncer de recto medio versus 6,0 cm en el cáncer de recto inferior; P = 0,03). En comparación con los tumores del recto medio, aunque en una cohorte muy pequeña, los tumores del recto inferior presentaron una tasa de afectación del CRM significativamente mayor (3 casos de afectación del CRM versus ninguno, P = 0,02) y así como un mayor número con escisión completa del mesorrecto grado 2 (4 pacientes versus 1 paciente; P = 0,02). No se encontraron diferencias significativas en los resultados oncológicos después de una mediana de seguimiento de 17 meses. CONCLUSIÓN: Aunque este estudio es el resultado de una pequeña cohorte, se debe prestar especial atención a los tumores de recto inferior voluminosos para reducir la tasa de positividad de CRM.

Lineage-specific telomere shortening and unaltered capacity for telomerase expression in human T and B lymphocytes with age.

Age effects on telomere length and telomerase expression in peripheral blood lymphocytes were analyzed from 121 normal individuals age newborn to 94 years and revealed several new findings. 1) Telomere shortening was observed in CD4+ and CD8+ T and B cells with age. However, the rate of telomere loss was significantly different in these populations, 35 +/- 8, 26 +/- 7, and 19 +/- 7 bp/year for CD4+ and CD8+ T and B cells, respectively. In addition, CD4+ T cells had the longest average telomeres at all ages, followed by B cells, with CD8+ T cell telomeres the shortest, suggesting that these lymphocyte populations may have different replicative histories in vivo. 2) Telomerase activity in freshly isolated T and B cells was indistinguishably low to undetectable at all ages but was markedly increased after Ag and costimulatory receptors mediated stimulation in vitro. Furthermore, age did not alter the magnitude of telomerase activity induced after stimulation of T or B lymphocytes through Ag and costimulatory receptors or in response to PMA plus ionomycin treatment. 3) The levels of telomerase activity induced by in vitro stimulation varied among individual donors but were highly correlated with the outcome of telomere length change in CD4+ T cells after Ag receptor-mediated activation. Together, these results indicate that rates of age-associated loss of telomere length in vivo in peripheral blood lymphocytes is specific to T and B cell subsets and that age does not significantly alter the capacity for telomerase induction in lymphocytes.