Accuracy of pelvic MRI in measuring tumor height in rectal cancer patients with or without preoperative chemoradiotherapy

A boundary-guided transformer for measuring distance from rectal tumor to anal verge on magnetic resonance images

Accurate measurement of the distance from the tumor's lowest boundary to the anal verge (DTAV) provides an important reference value for treatment of rectal cancer, but the standard measurement method (colonoscopy) causes substantial pain. Therefore, we propose a method for automatically measuring the DTAV on sagittal magnetic resonance (MR) images. We designed a boundary-guided transformer that can accurately segment the rectum and tumor. From the segmentation results, we estimated the DTAV by automatically extracting the anterior rectal wall from the tumor's lowest point to the anal verge and then calculating its physical length. Experiments were conducted on a rectal tumor MR imaging (MRI) dataset to evaluate the efficacy of our method. The results showed that our method outperformed surgeons with 6 years of experience (p < 0.001). Furthermore, by referring to our segmentation results, attending and resident surgeons could improve their measurement precision and efficiency.

Measuring distance from lowest boundary of rectal tumor to anal verge on CT images using pyramid attention pooling transformer

Accurately measuring the Distance from the lowest boundary of rectal tumor To the Anal Verge (DTAV) is critical for developing optimal surgical plans for treating patients with rectal cancer. DTAV was traditionally estimated by colonoscopy or manual measurement on computed tomography (CT) images. However, colonoscopy brings substantial pains to the patient. As for manual measurement on CT images, it is time-consuming and its accuracy depends on the surgeon's expertise. In this work, we present a novel method for automatically measuring DTAV from sagittal CT images. The success of our method is mainly credited to a pyramid attention pooling (PAP) transformer architecture, which naturally entangles global lesion localization and local boundary delineation. Our method automatically generates the rectum's centerline based on a segmented rectum and tumor image to simulate the manual measurement of DTAV. We conduct a comprehensive evaluation of the method with a newly collected rectum tumor CT image dataset. On a test dataset of 48 patients' CT images with rectal tumors, the mean absolute difference between our method and the gold standard is 1.74 cm, which is a significant improvement of 1.29 cm over that measured by a resident surgeon (P < 0.001). In addition, The results measured by the resident surgeon referring to our segmentation results improved by 1.46 cm compared to the results measured independently by the residents. As experimentally demonstrated, our method exhibits great application potential in clinical scenarios.

Lesion-to-anal-verge distance in rectosigmoid endometriosis on transvaginal sonography vs magnetic resonance imaging: prospective study

OBJECTIVES

To compare transvaginal sonography (TVS) and magnetic resonance imaging (MRI) with intraoperative measurement (IOM) using a rectal probe in the estimation of the location of rectosigmoid endometriotic lesions, i.e. lesion-to-anal-verge distance (LAVD), and to compare two different MRI techniques for measuring LAVD.

METHODS

This was a prospective single-center observational study that included women undergoing surgery for symptomatic rectosigmoid endometriosis by discoid (DR) or segmental (SR) resection from December 2018 to December 2019. TVS and MRI were performed presurgically for each participant to evaluate LAVD, and the measurements on imaging were compared with IOM using a rectal probe. Clinically acceptable difference and limits of agreement (LoA) between TVS and MRI compared with IOM were set at ± 20 mm. Two different measuring methods for MRI, MRI_Center and MRI_Direct , were proposed and evaluated, as there is currently no guideline to describe deep endometriosis on MRI. Bland-Altman plots and LoA were used to assess agreement of TVS and both MRI methods with IOM. Systematic and proportional biases were assessed using paired t-test and Bland-Altman plots.

RESULTS

Seventy-five women were eligible for inclusion. Twenty-eight women were excluded, leaving 47 women for the analysis. Twenty-three DR and 26 SR procedures were performed, with both procedures performed in two women. The Bland-Altman plots showed that there were no systematic differences between TVS or MRI_Center when compared with IOM for all included participants. MRI_Direct systematically underestimated LAVD for lesions located further from the anal verge. TVS, MRI_Center and MRI_Direct had LoA outside the preset clinically acceptable difference when compared with IOM. LAVD was within the clinically acceptable difference from IOM of ± 20 mm in 70% (33/47) of women on TVS, 72% (34/47) of women on MRI_Center and 47% (22/47) of women on MRI_Direct .

CONCLUSIONS

TVS should be the preferred method to estimate the location of a rectosigmoid endometriotic lesion, i.e. LAVD, as it is more available, less expensive and has a similar accuracy to that of MRI. Estimating LAVD can be relevant for planning colorectal surgery for rectosigmoid endometriosis. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

ACR Appropriateness Criteria® Staging of Colorectal Cancer: 2021 Update

Preoperative imaging of rectal carcinoma involves accurate assessment of the primary tumor as well as distant metastatic disease. Preoperative imaging of nonrectal colon cancer is most beneficial in identifying distant metastases, regardless of primary T or N stage. Surgical treatment remains the definitive treatment for colon cancer, while organ-sparing approach may be considered in some rectal cancer patients based on imaging obtained before and after neoadjuvant treatment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Measuring Rectal Cancer Tumor Height: Concordance Between Clinical Examination and MRI

BACKGROUND

Rectal cancer is categorized into categories on the basis of tumor height measurements. Tumor height is used to guide initial treatment and determines the eligibility for clinical trials.

OBJECTIVE

This study aimed to determine the concordance between tumor heights measured by MRI and by clinical examination.

DESIGN

This was an institutional review board-approved retrospective analysis of MRI and the clinical measurements of tumor height.

SETTING

This study was conducted at a single university center that was accredited by the Commission on Cancer National Accreditation Program for Rectal Cancer.

PATIENTS

Ninety-five patients who were treated between 2015 and 2019 and who had an MRI and clinical evaluation were included.

MAIN OUTCOME MEASUREMENTS

The mean difference of tumor height between MRI and clinical examination was calculated. Secondary outcomes were to assess whether position in the rectum, age, BMI, or sex would affect the difference and how the measurements would change eligibility for rectal cancer trials.

RESULTS

Tumor height measurement by MRI and clinical examination had a good correlation, with r = 0.89 and p < 0.001. The mean absolute difference of measurement of tumor height was 1.56 cm. Higher tumors had a larger absolute difference between measurements. Body mass index was significantly associated with the difference in measurements. The discordance in measurements led to a change in eligibility for clinical trials for 38.9% of patients. Clinical trial eligibility was not significantly associated with tumor height category, sex, or patient age.

LIMITATIONS

This study was conducted at a single center with retrospective methodology.

CONCLUSIONS

Although MRI and clinical measurements showed a strong correlation, nearly 40% of our patients had a change in clinical trial eligibility depending on measurement modality. We suggest that trial investigators be consistent in establishing measurement technique as their inclusion criterion. See Video Abstract at http://links.lww.com/DCR/B756.

MEDICIN DE LA ALTURA DEL TUMOR DE CNCER DE RECTO CONCORDANCIA ENTRE EL EXAMEN CLNICO Y LA RESONANCIA MAGNTICA

ANTECEDENTES:El cáncer de recto se clasifica en categorías basadas en las mediciones de la altura del tumor. La altura del tumor se usa para guiar el tratamiento inicial y determina la elegibilidad para los ensayos clínicos.OBJETIVO:Determinar la concordancia entre la altura de los tumores medida por resonancia magnética (RMN) y por examen clínico.DISEÑO:Este fue un análisis retrospectivo aprobado por el IRB de la resonancia magnética y las mediciones clínicas de la altura del tumor.AJUSTE:Esto se llevó a cabo en un único centro universitario que fue acreditado por el Programa Nacional de Acreditación del Cáncer de Recto de la Comisión de Cáncer.PACIENTE:Se incluyeron 95 pacientes que fueron atendidos entre 2015 y 2019 y que tuvieron una resonancia magnética y evaluación clínica.PRINCIPALES MEDIDAS DE RESULTADOS:Se calculó la diferencia media de la altura del tumor entre la resonancia magnética y el examen clínico. Los resultados secundarios fueron evaluar si la posición en el recto, la edad, el índice de masa corporal (IMC) o el sexo afectarían la diferencia y cómo las mediciones cambiarían la elegibilidad para los ensayos de cáncer de recto.RESULTADOS:La medición de la altura del tumor por resonancia magnética y el examen clínico tuvo una buena correlación con r = 0,89 y p < 0,001. La diferencia absoluta media de medición de la altura del tumor fue de 1,56 cm. Los tumores más altos tenían una diferencia absoluta más grande entre las mediciones. El IMC se asoció significativamente con la diferencia en las mediciones. La discordancia en las mediciones llevó a un cambio en la elegibilidad para los ensayos clínicos para el 38,9% de los pacientes. La elegibilidad para ensayos clínicos no se asoció significativamente con la categoría de altura del tumor, el sexo o la edad del paciente.LIMITACIONES:Se realizó en un solo centro con metodología retrospectiva.CONCLUSIONES:Aunque la resonancia magnética y las mediciones clínicas mostraron una fuerte correlación, casi el 40% de nuestros pacientes tuvieron un cambio en la elegibilidad para los ensayos clínicos según la modalidad de medición. Sugerimos que los investigadores del ensayo sean coherentes al establecer la técnica de medición como criterio de inclusión. Consulte Video Resumen en http://links.lww.com/DCR/B756.

Morphometric assessment of the mesorectal fat in Chinese Han population: A clinical MRI study

The study aimed to analyze morphometric assessment of the mesorectal fat thickness and its correlation with body mass index in Chinese Han population. The anterior, posterior, right lateral, and left lateral mesorectal fat thickness were measured using MRI T2-weighted images. The mean distance from the rectal wall to the mesorectal fascia were 3.8, 8.4, 11.3, and 11.7 mm in anterior, posterior, right lateral, and left lateral portion, respectively. The mesorectal area, rectal area, mesorectal fat thickness area, and rectal height were 2395.3 ± 691.1 mm2, 709.6 ± 403.5 mm2, 1685.7 ± 525.3 mm2, and 9.1 ± 0.8 cm. BMI was found to be directly proportional to and statistically significant to the mesorectal fat area (p = 0.01). Since the mean mesorectal fat thickness was found to be <12 mm, T3d staged rectal cancer is less likely to be found in an average Chinese population that may affect the overall-survival and progression-free survival in rectal cancer patients. Anterior portion of the rectum was least thick compared to all other sides. Therefore, extra-caution should be taken in handling tumors on the anterior part of the rectum.

Measurement of rectal tumor height from the anal verge on MRI: a comparison of internal versus external anal sphincter

PURPOSE

To determine the most accurate measurement technique to assess rectal tumor height on MRI using two different anatomic landmarks for the anal verge.

INTRODUCTION

Accurate measurements and standardized reporting of MRI for rectal cancer staging is essential. It is not known whether measurements starting from the internal anal sphincter (IAS) or external anal sphincter (EAS) more closely correlate with tumor height from the anal verge on endoscopy.

METHODS

This retrospective study included baseline staging MRI examinations for 85 patients after exclusions. Two radiologists blinded to endoscopic results measured the distance of rectal tumors from the internal anal sphincter and external anal sphincter on sagittal T2 images. The reference standard was endoscopic measurement of tumor height; descriptive statistics were performed.

RESULTS

For reader 1, the mean difference in measurement of tumor height between MRI and endoscopy was - 0.45 cm (SD ± 1.76 cm, range - 6.0 to 3.9 cm) for the IAS and 0.51 cm (SD ± 1.75 cm range - 4.7 to 4.8 cm) for the EAS. For reader 2, the mean difference in measurement of tumor height between MRI and endoscopy was - 0.57 (STD ± 1.81, range - 5.9 to 4.8 cm) for the IAS and 0.52 cm (STD ± 1.85, range - 4.3 to 5.6 cm) for the EAS. Interobserver ICC was excellent between reader 1 and reader 2 for measurements from both the IAS (0.955 95% CI 0.931-0.97) and EAS (0.952, 95% CI 0.928, 0.969).

CONCLUSION

Measurement of tumor height on MRI was highly reproducible between readers; beginning measurements from the EAS tends to slightly overestimate tumor height on average and from the IAS tends to slightly underestimate tumor height on average.

Current controversy, confusion, and imprecision in the use and interpretation of rectal MRI

There has been a rapid increase in the utilization of MRI in rectal cancer staging in the USA essentially replacing endorectal ultrasound and mimicking the trend in Europe seen in the 1990s and 2000s. Accompanying this trend, there is a demand, and recognized need, for greater precision and clarification of confusing, misunderstood and poorly understood concepts, facts, statements and nomenclature regarding rectal cancer and the use of pelvic MRI for diagnosis. As such, this Review, part evidence-based and part expert opinion, will attempt to elucidate and clarify several concepts the authors have encountered in 25 years of imaging rectal cancer, focusing on MRI.