Rectal Wall Research Articles

Rectal linitis plastica as the sole manifestation of breast cancer recurrence.

We present the case of a 51-year-old woman with a history of invasive lobular breast adenocarcinoma in remission for six years following surgery, chemoradiotherapy, and hormone therapy. During follow-up, an asymptomatic elevation of CA 15-3 was detected. A CT scan revealed rectal wall thickening suggestive of neoplasia, with no other lesions observed. Colonoscopy demonstrated a congested, thickened, and infiltrative mucosa in the rectal ampulla extending from the internal anal margin, accompanied by an impassable stricture 8 cm from the anal margin. Initial endoscopic biopsies were negative for malignancy. Endoscopic ultrasound (EUS) revealed rectal wall thickening, loss of normal wall stratification, and a regular outer border, findings consistent with rectal linitis plastica. The stricture prevented further advancement of the echoendoscope, but fine-needle biopsies were performed. Histological analysis confirmed adenocarcinoma infiltration of breast origin.

OP-TNT: Phase II study of total neoadjuvant chemoradiotherapy followed by local resection for early distal rectal carcinoma.

177 Background: Surgery is standard of care for pMMR early distal rectal cancer (RC), which can be partially exempted by totally neoadjuvant chemoradiotherapy (TNT) followed by watch and wait. But long-term data showed that 1/3 patients had local growth( mostly in the rectal wall)in two years. This study investigates the efficacy and safety of TNT followed by local excision( LE) for early distal rectal carcinoma (cT1-3N0M0) in order to preserve organs. Methods: In this single-arm, phase 2 prospective trial, patients were eligible if they were aged 18 years or older, with a performance status of 0-1,newly diagnosed, biopsy proven pMMR/MSS RC which located ≤5cm from the anal verge and staged as cT1-3N0M0. Patients were assigned to receive TNT: 6 courses of CapOx(capecitabine 1000 g/m2 PO BID D1-14, oxaliplatin 130 mg/m2 IV QD D1,Q3W), combined with concurrent long-course radiotherapy (LCRT)(45 Gy/25 Fx to the pelvis with an SIB of 50 Gy/25 Fx to the tumor bed). Evaluation was performed 12 weeks after completion of LCRT. Patients who achieved a clinical complete response (cCR) or near clinical complete response (ncCR)were assigned to LE, whereas those with >ypT1, positive margin, or neurovascular invasion after LE were recommended for total mesorectal excision (TME). The primary endpoint is the 3-year organ-preserving rate. Secondary endpoints include the pathological complete response (pCR)(encompassing response after LE and TME), adverse effects rate, 3y-disease-free survival (DFS)and 3y-overall survival (OS)rate. Results: From October 2022 to August 2024, 52 patients had completed therapy. Median age at evaluation and follow-up duration were 58.3 years and 11 months. Of the patients 78.8% (41/52) were defined as MRI stage T3, and 76.9%(40/52) located ≤3cm from the anal verge. Of 52 evaluable patients ,82.7% (43/52) achieved cCR/ncCR and had LE (6 via endoscopic resection and 37 through trans-anal minimally invasive surgery). Among these patients, 25.6% (11/43) were found to have residual tumors after LE, of which 6 were radical-operated while 5 refused this intervention. Nine patients who did not achieve cCR or ncCR received TME resection, and 6 of them were confirmed as pCR. The total pCR rate was 73.1% (38/52). Of all patients, 3 underwent abdominoperineal resection, and sphincter-preserving rate was 94.2%(49/52). No grade 3 or 4 adverse events were reported, and there were no treatment-related deaths. The main adverse event after local resection was the 1-3 months anterior resection syndrome. Conclusions: The results of interim analysis showed that tumor residue was found in patients with cCR/ncCR after TNT, similar to the regrowth rate previously reported. LE strategy may become prevention. Long-term outcomes are being followed up. Clinical trial information: NCT05563922 .

P0280 Evaluation of the diagnostic accuracy of trans-perineal ultrasound for predicting rectal histoendoscopic remission in Ulcerative Colitis (The TRINITY Study): A prospective, paired, comparative study with endoscopic ultrasound and trans-abdominal ultrasound

Abstract Background Rectum, frequently involved in Ulcerative colitis (UC) is challenging to evaluate using trans-abdominal sonography (TAS). Earlier single centre study have shown that rectal total wall thickness (TWT) (<4 mm) on trans-perineal ultrasound (TPUS) accurately predicts rectal inflammation(1). Inspite of being point-of-care, TPUS can only evaluate the lower rectum (~5 cm) and studies with trans-vaginal ultrasound have shown higher cut offs for rectal TWT(2). This study (comparison of TRIple Rectal UltrasouNd Imaging Technology : TRINITY) aimed to comprehensively evaluate the diagnostic accuracy of TPUS in predicting rectal histoendoscopic activity, using endoscopic ultrasound (EUS) as the reference standard. Methods 114 UC patients [age 18-70 yr (median- 37), 64 % male, E1: 16, E2: 61, E3: 37] underwent point-of-care TAS and TPUS followed by sigmoidoscopy with biopsy and rectal EUS. On TAS and TPUS, rectal TWT (average of anterior and posterior) and vascularity (Modified Limberg Score, MLS) were evaluated. On EUS, rectal TWT (average of upper, middle and lower and separately lower), vascularity (MLS), mucosal thickness (MT), and submucosal thickness (SMT) were measured. Diagnostic accuracy for predicting endoscopic activity (Ulcerative colitis endoscopic index of severity: UCEIS>1 in rectum) and histologic activity (Nancy Index≥1) was evaluated using receiver operating characteristic (ROC) curves. Results For prediction of both endoscopic and histologic activity, EUS outperformed TPUS. TAS was not useful (p>0.05) For endoscopic activity (n=114): EUS: Mucosal thickness>0.95 mm: AUC:0.95 (p<0.001); average TWT> 4 mm: AUC:0.89 (p<0.001); Vascularity (MLS) >1: AUC:0.93 (p<0.001); SMT>2.2 mm: AUC:0.84,(p<0.001). TPUS: rectal TWT >5.6 mm: AUC:0.68 (p=0.001); MLS ≥1:AUC:0.74 (p<0.001). TAS: TWT >6.3 mm:AUC: 0.57(p=0.25); MLS ≥1:AUC: 0.61 (p=0.04). For predicting histologic activity(n=81): EUS: lower rectal vascularity (MLS ≥1): AUC: 0.84, p<0.001; SMT>2.1 mm: AUC: 0.71, p<0.001; MT≥1 mm: AUC:0.81, p<0.001; TWT>5.6 mm: AUC:0.65, p=0.02. TPUS:rectal TWT≥ 5.6 mm: AUC:0.65 (p=0.02); vascularity (MLS≥1) AUC: 0.65 (p=0.036). TAS:TWT ≥ 6.3 mm: AUC:0.56, p=0.44; vascularity (MLS ≥1), AUC:0.59, p=0.18. Conclusion Although EUS remains the gold standard for assessing rectal inflammation, its invasive nature limits routine clinical use. TPUS offers a point-of-care, non-invasive alternative with moderate accuracy for predicting histoendoscopic remission with higher cut off levels contrary to previous reports. Further refinements in TPUS techniques and protocols are warranted to enhance its widespread applicability in clinical practice.

P0272 Evaluation of Rectal Wall Thickness Measurement Sensitivity via Transabdominal Ultrasound to Assess Mucosal Activity in Ulcerative Colitis: Could This Be a Useful Non-Invasive Tool? A Preliminary Analysis.

Abstract Background Ulcerative colitis (UC) is a chronic inflammatory bowel disease where accurate assessment of disease activity is essential for patient management. Endoscopy is the gold standard for evaluating mucosal inflammation, but non-invasive alternatives, such as transabdominal ultrasound (TAUS), are garnering interest. This study aimed to evaluate the sensitivity of rectal wall thickness measurement using TAUS to assess UC activity, comparing to endoscopic and histological findings. Methods In a prospective, observational study, we enrolled consecutive adult patients with UC who were referred to our tertiary center from May to October 2024. Eligibility required a scheduled TAUS before 30 days of a staging colonoscopy, without intervening therapy adjustments. Exclusion criteria included technically inadequate TAUS readings (e.g., due to anatomical variations or excessive gas interposition). In all patients we evaluated rectal wall thickness and laboratory parameters such as C-Reactive Protein and fecal calprotectin. Disease activity was assessed by endoscopist (MAYO score). Histological status (active/inactive) and additional clinical data, including disease duration, extent, and UC treatment, were recorded. Results We studied 29 patients (51.7% females, median age 55 years). The median UC duration was 10 years, and most patients had proctitis or left-sided colitis (37.9% each). Patients with an endoscopic MAYO score of 0 or 1 had a median rectal wall thickness of 4.7 mm (IQR 4.5-5.5), while those with a score of 2 or 3 had a median of 7.0 (IQR 5.3-7.4 mm, p=0.005). ROC analysis of TAUS rectal wall thickness revealed significant discriminatory capability for endoscopic activity (AUC: 0.833, CI 95%, 0.678-0.989), while the same figures for fecal calprotectin and C-Reactive Protein were 0.890 (CI 95%, 0.671-1.000) and 0.774 (CI 95%, 0.604-0.944), respectively. For histological activity, accuracy of rectal wall thickness, fecal calprotectin, and C-Reactive Protein were 0.796 (CI 95%, 0.620-0.972), 0.790 (CI 95%, 0.605-0.975), and 0.645 (CI 95%, 0.429-0.861), respectively. Conclusion This preliminary analysis showed that rectal wall thickness measured by TAUS has a high accuracy in identifying both endoscopic and histologic activities in patients with UC, positioning it as a promising tool to avoid endoscopy. Future studies with larger cohorts are needed to confirm these findings and further optimize the use of TAUS in this setting.

Risk factors for rectal wall infiltration in hydrogel spacer placement: Influence of biopsy approach.

This study aimed to investigate the association between the type of prostate biopsy and the occurrence of rectal wall infiltration (RWI) with hydrogel spacer placement in patients undergoing radiotherapy for prostate cancer. A retrospective study was conducted involving 175 patients who received hydrogel spacer placement before radiotherapy at the National Cancer Center East Hospital, between October 2021 and December 2023. The patients were categorized based on the type of prostate biopsy: transperineal and transrectal. Spacer placement was followed by MRI to confirm spacer position. Logistic regression analysis was employed to identify factors associated with significant RWI. Of the 175 patients analyzed, 115 underwent transperineal biopsy (TPB) and 60 underwent transrectal biopsy (TRB). The median age was 74 years, and the median prostate volume was 18.6 mL. RWI occurred in 44 (25.1%) of all cases. TRB was associated with a significantly higher occurrence of RWI grade ≥2 compared to TPB (23.3% vs. 4.3%, p < 0.001). Multivariate analysis identified TRB (OR = 5.81, 95% CI = 1.91-17.60, p = 0.002) and smaller prostate volume (≤18.0 mL) (OR = 4.23, 95% CI = 1.23-13.90, p = 0.018) as significant risk factors for RWI grade ≥2. The study found that TRB significantly associated the risk of RWI following hydrogel spacer placement in prostate cancer radiotherapy. Smaller prostate volumes also heightened this risk. These findings highlight the importance of considering biopsy type and prostate size in planning spacer placement.

Linear endo-ultrasonographic signs of muscularis propria invasion in early rectal cancer

Background and study aimLocal resection of early rectal cancer is being increasingly used. With invasion of the muscularis propria layer of the rectal wall, the risk of lymph node metastasis becomes too high to consider this the optimal oncological treatment. Therefore, a diagnosis of muscular invasion is important before attempting local resection; however, endoscopic and magnetic resonance imaging (MRI) images have limitations, such as overstaging (26–31%). We investigated the potential of linear endoscopic ultrasound (L-EUS) in the diagnosis of muscularis propria invasion.Patients and methodsThe study consisted of a development phase, in which linear (L)- EUS features, associated with muscular wall invasion were searched and tested, and a validation phase, during which 30 representative videos were assessed by the author F.t.B. and four experienced endosonographists without experience in rectal L-EUS.ResultsThe development cohort consisted of 91 patients (2019–2023). Overall, six EUS features were found to be significantly associated with muscular wall invasion: tornado sign, blob sign, massive connection, layer split, extramural deposit, and, most importantly impaired shiftability between the lesion and muscularis propria layer. During the development phase, these findings demonstrated excellent diagnostic features (sensitivity, 94.4%; specificity, 97.9%; and overstaging, 4%). In the validation phase, the sensitivity, specificity, and overstaging by F.t.B. were 88%, 85%, and 12%, respectively. Among the four inexperienced reviewers, the percentages were 65%–71%, 46%–54%, and 33%–39%, respectively. When considering the 27 videos that were considered easy or moderately difficult to assess, only 55% were correctly interpreted by the inexperienced reviewers.ConclusionsLinear endoscopic ultrasonography may be a valuable tool for the assessment of ingrowth into the muscularis propria in supposedly early rectal cancer, especially using its dynamic potential to assess fixation to the muscular wall by moving the lesion. However, training will be required to achieve satisfactory results.

Risk factors for rectal perforation during presacral cyst removal: a comparison between transabdominal, perineal, and combined surgical approaches.

This study aimed to evaluate the risk factors associated with rectal perforation during various surgical interventions for presacral cysts. This retrospective study included 73 participants from 2013 to 2023 who met the inclusion criteria. Participants underwent surgical treatments through transabdominal, perineal, or combined approaches. Preoperative assessments of presacral cysts were performed using computed tomography (CT) and magnetic resonance imaging (MRI). Biannual postoperative follow-ups involved ultrasound, CT, or MRI scans. Data analysis was conducted using RStudio software. The incidence of rectal perforation did not differ significantly across surgical approaches [combined 2 (18%) vs. perineal 3 (8.8%) vs. transabdominal 4 (14%), P = 0.7]. Cyst capsule rupture was more frequent in the transabdominal and combined approaches [17 (61%) and 5 (45%), respectively] versus perineal approach [8 (24%), P = 0.011]. The laparoscopic subgroup experienced a higher rate of cyst rupture compared to the robotic subgroup, with rectum perforation cases only correlating with ruptures in the robotic subgroup. Intraoperative complications prompted conversions to open surgery in the laparoscopic group, unlike in the robotic group. Postoperative follow-up revealed no mortalities, with malignant transformation observed in two cases and local recurrences in three. While univariate analysis did not identify significant predictors of rectal wall perforation, multivariate analysis suggested that the risk of perforation increased with cyst rupture and decreased when the cyst was located further from the anal verge. The study identifies two primary risk factors for rectal wall perforation: the cyst capsule integrity and the cyst-rectum shortest distance, with the latter being accurately determined by MRI. These findings may inform further surgical planning and risk assessment.

Development and Validation of a Multimodal Machine Learning Model for Diagnosing and Assessing Risk of Crohn's Disease in Patients With Perianal Fistula.

Diagnosis of Crohn's disease (CD) can pose challenges, particularly when perianal fistula is the initial presentation. To develop and validate a predictive model, establishing a visual web tool for early diagnosis of CD in patients presenting with perianal fistula. This retrospective, multicentre validation study involved patients diagnosed with either perianal fistulising CD or cryptoglandular fistula who underwent initial perianal fistula surgery subsequent to rectal MRI at three Chinese centres from September 2016 to December 2020. A random forest classification model was trained on the derivation cohort (n = 550), randomly split into training and test sets at a 7:3 ratio. Validation utilised data from two external centres (n = 300). Model interpretation employed the Shapley Addictive explanation (SHAP) framework. The validated model was integrated into a web tool for calculating patient-specific risk. In the derivation cohort, SHAP analysis highlighted rectal wall ulceration, rectal wall thickening, submucosal fistula, and T2 hyperintensity as risk factors, while age was identified as protective. A random forest classification model developed using these top 5 features achieved an AUROC of 0.9425 (95% CI: 0.8943-0.9906). In the validation cohort, the model performed well with AUROC values of 0.9187 (95% CI: 0.8620-0.9754) and 0.9341 (95% CI: 0.8876-0.9806), respectively. We developed a publicly accessible web-based application. We have developed a multimodal machine learning model and a web tool that can predict and present CD risk in patients initially presenting with perianal fistula.

Validating knowledge-based volumetric modulated arc therapy plans with a multi-institution model (broad model) using a complete open-loop dataset for prostate cancer.

This study examined the characteristics of the broad model (KBPbroad) through a complete open-loop evaluation of volumetric modulated arc therapy (VMAT) plans for prostate cancer in 30 patients at two institutions. KBPbroad, trained using 561 prostate cancer VMAT plans from five institutions with different treatment protocols, was shared with two institutions. The institutions were not involved in the creation of KBPbroad. Plan created with KBPbroad were compared with clinical plans (CPs) and plans created using a single-institution model at each institution (KBPonsite). KBPbroad maintained the target coverage of CPs while meeting dose limits across varied settings at each institution. At institution X, KBPbroad provided 40, 60, and 70Gy (V40Gy, V60Gy, and V70Gy, respectively) to 30.8% ± 9.9%, 15.3% ± 8.5%, and 9.0% ± 6.4% of the volume at the rectal wall, respectively, which were significantly smaller than those provided by KBPonsite and CPs. At institution Y, compared with CPs, KBPbroad provided significantly greater V50Gy, V70Gy, dose to 2% of the volume (D2%) at the rectum, and D2% at the bladder but significantly lower V50Gy and V70Gy at the bladder, in addition to superior dose homogeneity and conformality at the planning target volume. Our complete open-loop evaluation of VMAT plans for prostate cancer at two institutions demonstrated the clinical effectiveness of KBPbroad at institutions producing plans with insufficient reductions in OAR doses. Thus, the quality of KBPbroad plans is likely greater than that of KBPonsite plans and CPs.

A rectal ulcer caused by hydrogel spacer insertion: A case report and review of the literature.

A 75-year-old man presented with hematochezia. He had been diagnosed with prostate cancer (stage 1) 1 month previously and had undergone gold marker injection and hydrogel spacer insertion 3 weeks previously to prepare for radiotherapy. Hydrogel spacer insertion is a safe procedure that can prevent the side effects of radiotherapy for prostate cancer. A computed tomography evaluation identified a low-density area that extended from the prostate to the rectal wall. Magnetic resonance imaging of the abdomen revealed the hydrogel spacer between the anterior rectal wall and prostate. A colonoscopy revealed an approximately 2 cm ulcer in the rectum. The patient was diagnosed with a rectal ulcer with bleeding caused by hydrogel spacer insertion. Conservative follow-up was performed, and his condition improved over time. Radiotherapy for prostate cancer was initiated 4 months after hydrogel spacer insertion. The patient has not experienced any abdominal symptoms such as bloody stools since that time. Because the incidence of prostate cancer is increasing, the number of such cases is likely to increase in the future.

A Case of Fever of Unknown Origin -? Melioidosis Presenting as Severe Sepsis and Multiple Organ Dysfunction Syndrome

Melioidosis is an emerging infection in India1, well known for its protean clinical manifestations. We report a case of probable disseminated Melioidosis with hyperferritinemic septic shock and multi organ dysfunction syndrome. She presented as a case of PUO- with high fever- 1week, loose stools, headache and shortness of breath, to our hospital. She had a turbulent course in hospital, with fever not responding despite 2 weeks of hospitalization. Her respiratory system showed bilateral crackles. Per Abdomen examination revealed tenderness in right iliac fossa, suprapubic region and left iliac fossa, bowel sounds were sluggish. CECT chest and Abdomen showed right basal pneumonia, hydro-ureteronephrosis, with ureter showing narrowing at the region of right adnexa, PID, subcentrimetric , mesentric , and perirectal lymph nodes; rectal wall showing inflammatory changes with inflammation of mesorectal fascia . She responded well and fully recovered with injection Meropenem for 8 weeks; followed by oral Trimethoprim-Sulfamethoxazole for 3 months.

Value of transabdominal ultrasonography for diagnosing functional constipation in children: a systematic review and meta-analysis.

Transabdominal ultrasonography is increasingly used as a novel modality for detecting pediatric functional constipation (FC). This systematic review and meta-analysis aimed to assess the diagnostic parameters of FC including rectal diameter (RD) and anterior rectal wall thickness. A systematic search was conducted of the Ovid MEDLINE, EMBASE, Scopus, and PubMed databases through September 29, 2023, to identify studies comparing RD and anterior wall thickness using transabdominal ultrasonography in children with versus without FC. Meta-analyses were performed using random-effects models to calculate the weighted mean differences in RD and anterior wall thickness. Comprehensive Meta-Analysis ver. 3, R, and Review Manager ver. 5.4.1 software were used to assess the optimal cutoff, sensitivity, specificity, and area under the curve (AUC). Fourteen studies involving 1,255 children (mean age, 6.21  2.3 years) were included. The mean RD was significantly larger in constipated children versus controls (mean difference [MD] = 10.35 mm; 95% confidence interval [CI], 6.97-13.74; P < 0.001; I2 = 94%). A meta-regression showed no significant effects of age, weight, or height on RD. An optimal RD cutoff point of 31 mm was suggested by a pooled analysis with an AUC of 0.86 (95% CI, 0.8-0.91; P < 0.001), sensitivity of 0.75 (95% CI, 0.59-0.86), and specificity of 0.84 (95% CI, 0.68-0.93). The mean anterior rectal wall thickness was greater among constipated children than among controls (MD = 0.44; 95% CI, -0.26 to 1.13; P = 0.22), but this difference was not statistically significant. RD measured using transabdominal ultrasonography with a cutoff point of 31 mm exhibited good diagnostic accuracy for diagnosing FC in children.

Ethanol sclerotherapy in pediatric rectal prolapse: efficacy, complications, and influencing factors

IntroductionRectal prolapse is prevalent in children and the elderly, impacting quality of life significantly. Traditional surgical interventions carry risks, especially in pediatric patients. Ethanol sclerotherapy offers a less invasive alternative, inducing fibrosis and thickening of the rectal wall. Despite its potential benefits, procedural complications are possible, emphasizing the need for careful patient selection and procedural expertise. This study aims to evaluate the safety and efficacy of sclerotherapy in treating rectal prolapse in a tertiary referral center in southern Iran.MethodsPatient records from Nemazee Hospital covering January 2014 to December 2023 were retrospectively analyzed. Pediatric patients undergoing ethanol sclerotherapy for rectal prolapse were included. Data on demographics, presentation, procedures, and outcomes were collected. Ethical approval was obtained, and specific inclusion/exclusion criteria were applied. Statistical analyses were conducted using SPSS version 26.ResultsOne hundred thirty patients were evaluated, with a mean age of 10.74 ± 5.320 years. Most patients experienced constipation (56.9%). 74.2% responded well to sclerotherapy, with 12.9% needing a second injection. Complications were minimal, with bleeding being the most common (4.6%). Recurrence occurred in 18.6% of cases. Male patients showed a higher total complication rate (P = 0.010). Diarrhea-dominant patients had no recurrences post-sclerotherapy. Age significantly influenced treatment response and recurrence (P = 0.017, P = 0.035).ConclusionMale predominance contradicted global pediatric rectal prolapse ratios, possibly influenced by cultural factors. Sclerotherapy remains effective, though response rates vary. Older age correlated with lower response rates and higher recurrence. Constipation-dominant prolapse was associated with increased recurrence risk. Male patients had a higher complication rate, highlighting the need for tailored management strategies.

Feasibility of creating a daily adaptive plan using automatic DIR-created target and OARs contours in patients with prostate cancer magnetic-resonance-guided adaptive radiotherapy.

The purpose of this study was to evaluate the feasibility of treatment plans for prostate cancer with magnetic resonance (MR)-guided online adaptive radiotherapy, which are generated using deformable image registration (DIR)-created contours of the targets and organs. Totally, 150 fractions from 30 prostate cancer patients implanted with a hydrogel spacer and treated with the MR-Linac were studied. Reference treatment plans that satisfied all institutional dose constraints were initially created on planning MRI. The adaptive treatment plans were created on daily MRI based on the reference plan using the DIR-created contours, ensuring all dose constraints were met. Subsequently, a clinician manually created reference contours for each daily MRI. Finally, the dose volume histogram indices of the plan generated with DIR-created contours were re-evaluated with clinician created contours. The evaluated contours included the bladder wall, rectum wall, sigmoid, small bowel and planning target volume (PTV) for dose prescription. The PTV for dose prescription met the dose constraints in all fractions. The bladder and rectum walls met the dose constraint of maximum dose (D0.03 cc) in all fractions. Five patients failed to meet the sigmoid and small bowel dose constraints, with the largest deviation being 13.3% exceedance at D2 cc in the small bowel added 3mm margin. This study suggests that most treatment plans created without modifying the DIR-created contours are clinically viable. However, dislodgements of the small bowel and sigmoid may exceed the extent of DIR propagation from the reference plan contours, and it is recommended that these contours be verified.

Giant pelvic dermoid cyst in a 17-year-old girl

BACKGROUND: Dermoid cysts in the presacral and retrorectal space in children are relatively rare. However, even more rarely, they have clinical manifestations at patient’s early age and so, can be silent for a long time. CLINICAL CASE DESCRIPTION: The article describes a rare clinical observation — a giant dermoid cyst in the retrorectal space in a 17-year-old girl. The child had a tendency to constipation from her early childhood. Menses started at age 13, painful. During the last year, disorders in her menstrual cycle were noticed. The girl was examined by a gynecologist. Ultrasound examination revealed a cystic formation in the pelvic cavity up to 9 cm in diameter. Non-malignant nature of the process was confirmed by: normal level of cancer markers (α-fetoprotein, β-human chorionic gonadotropin), single node, clearly defined formation capsule, homogeneous nature of its contents, no invasive growth and lesions in the regional lymph nodes. Magnetic resonance imaging with intravenous contrasting defined a true relationship of the cystic formation with other organs and structures of the pelvic cavity. The cystic formation caused deformation of the cervix, vagina, and rectum. The obtained findings allowed to plan surgical intervention correctly. Surgical access-transverse in the coccyx projection up to 10 cm long. The cystic formation was a thin-walled connective tissue capsule with a yellowish content. Due to very large cyst dimensions, first it was opened in a limited area and emptied. Then the capsule was isolated and completely removed. The cyst intimately adhere to rectum, vagina, and cervix walls. Histological conclusion: "Capsule of a dermoid cyst with hemorrhages". The postoperative period was smooth. The patient recovered, all disease manifestations disappeared. She was discharged home in a satisfactory state. Follow-up visits were in 6 and 12 months after surgery. No evidence of possible relapse. CONCLUSION: There are only few descriptions of such cases in the available literature. Ultrasound and MRI examinations allowed to have a full picture of dermoid cyst position and its connection with other pelvic organs due to which surgeons could develop a correct plan for surgical intervention.

SpaceOAR Persistence on MRI at 59 Weeks Postplacement in a Patient With Stage IV CKD

External beam radiation therapy is commonly used to treat prostate cancer, and gel spacers such as SpaceOAR Hydrogel (Boston Scientific, Marlborough, MA) are approved to limit local rectal radiation toxicity. SpaceOAR is usually reabsorbed in 12 to 24 weeks and excreted renally. It has a known low rate of rectourethral fistula that is usually associated with ectopic placement into the rectal wall. We present a case of a SpaceOAR Hydrogel insert persisting in a patient with chronic kidney disease on serial MRI scans for 59 weeks after placement with colovesical fistula development 81 weeks after placement of unclear association.

058. A Rare Case: Anterior Wall Rectum Perforation Due to Intrauterine Device Migration

Background: Intrauterine devices (IUDs) are widely used for contraception due to their long-acting, safe, and effective nature in preventing pregnancy. However, common side effects and complications, such as vaginal bleeding, expulsion, displacement, translocation, and perforation necessitate attention, with translocation and perforation being rare but potentially severe, warranting prompt removal according to WHO recommendations. This study aims to document and analyze a rare case of rectal perforation resulting from the migration of an IUD. Case: A report was made from 31-year-old pregnant woman with a history of two cesarean sections presented with 10-day abdominal pain and an IUD inserted 42 days post-surgery, which MRI revealed had translocated into the left anterolateral rectal wall, prompting retroscopy for extraction. Uterine perforation and IUD migration into adjacent organs can result in various complications, including uterine, bladder, and intestinal perforation, with initial symptoms potentially being asymptomatic, emphasizing the need for routine check-ups. Retrieval of migrated IUDs can be achieved through methods such as endoscopy, laparoscopy, or laparotomy, as illustrated in a case involving a patient with abdominal pain and imaging evidence of IUD translocation to the rectum's anterior wall, managed through less invasive rectoscopy. Conclusion: Translocated IUDs may exhibit varying symptoms or none at all, necessitating removal regardless of type or location, with management guided by radiological and endoscopic findings alongside understanding abdominal organ anatomy

Deformable Mapping of Rectal Cancer Whole-Mount Histology with Restaging MRI at Voxel Scale: A Feasibility Study.

Purpose To develop a radiology-pathology coregistration method for 1:1 automated spatial mapping between preoperative rectal MRI and ex vivo rectal whole-mount histology (WMH). Materials and Methods This retrospective study included consecutive patients with rectal adenocarcinoma who underwent total neoadjuvant therapy followed by total mesorectal excision with preoperative rectal MRI and WMH from January 2019 to January 2022. A gastrointestinal pathologist and a radiologist established three corresponding levels for each patient at rectal MRI and WMH, subsequently delineating external and internal rectal wall contours and the tumor bed at each level and defining eight point-based landmarks. An advanced deformable image coregistration model based on the linearized iterative boundary reconstruction (LIBR) approach was compared with rigid point-based registration (PBR) and state-of-the-art deformable intensity-based multiscale spectral embedding registration (MSERg). Dice similarity coefficient (DSC), modified Hausdorff distance (MHD), and target registration error (TRE) across patients were calculated to assess the coregistration accuracy of each method. Results Eighteen patients (mean age, 54 years ± 13 [SD]; nine female) were included. LIBR demonstrated higher DSC versus PBR for external and internal rectal wall contours and tumor bed (external: 0.95 ± 0.03 vs 0.86 ± 0.04, respectively, P < .001; internal: 0.71 ± 0.21 vs 0.61 ± 0.21, P < .001; tumor bed: 0.61 ± 0.17 vs 0.52 ± 0.17, P = .001) and versus MSERg for internal rectal wall contours (0.71 ± 0.21 vs 0.63 ± 0.18, respectively; P < .001). LIBR demonstrated lower MHD versus PBR for external and internal rectal wall contours and tumor bed (external: 0.56 ± 0.25 vs 1.68 ± 0.56, respectively, P < .001; internal: 1.00 ± 0.35 vs 1.62 ± 0.59, P < .001; tumor bed: 2.45 ± 0.99 vs 2.69 ± 1.05, P = .03) and versus MSERg for internal rectal wall contours (1.00 ± 0.35 vs 1.62 ± 0.59, respectively; P < .001). LIBR demonstrated lower TRE (1.54 ± 0.39) versus PBR (2.35 ± 1.19, P = .003) and MSERg (2.36 ± 1.43, P = .03). Computation time per WMH slice for LIBR was 35.1 seconds ± 12.1. Conclusion This study demonstrates feasibility of accurate MRI-WMH coregistration using the advanced LIBR method. Keywords: MR Imaging, Abdomen/GI, Rectum, Oncology Supplemental material is available for this article. © RSNA, 2024.

Full bladder, empty rectum? Revisiting aparadigm in the era of adaptive radiotherapy.

Many patients find it challenging to comply with instructions regarding rectum and bladder filling during pelvic radiotherapy. With the implementation of online adaptive radiotherapy, the reproducibility of organ volumes is no longer aprerequisite. This study aims to analyze the sparing of the bladder and the posterior rectum wall (PRW) in conditions of full versus empty bladder and rectum. 280 fractions from 14 patients with prostate cancer who underwent adaptive radiotherapy using the Varian Ethos system were analyzed post-hoc. Various metrics for the bladder and PRW were correlated with respect to organ volume. Our analysis quantitatively confirms the advantage of afull bladder during radiotherapy, as metrics V48Gy and V40Gy significantly inversely correlate with bladder filling for each patient individually. While bladder volume did not show agradual decrease over the course of radiotherapy, it was observed to be higher during planning CT scans compared to treatment sessions. Afull rectum condition either significantly improved (in 2 out of 7 patients) or at least did not impair (in 5 out of 7 patients) PRW sparing, as represented by the V30Gy metric, when patients were compared individually. The average V30Gy across all patients demonstrated asignificant improvement in PRW sparing for the full rectum condition, with a[Formula: see text]-value of 0.039. Despite the implementation of adaptive therapy, maintaining ahigh bladder filling remains important. However, the recommendation for rectum filling can be abandoned, as reproducibility is not critical for adaptive radiotherapy and no dosimetric advantage per se is associated with an empty rectum. Patients may even be encouraged not to void their bowels shortly before treatment, as long as this is tolerated over the treatment session.

On the trail of CBCT-guided adaptive rectal boost radiotherapy, does daily delineation require a radiation oncologist?

IntroductionDose-escalation radiotherapy for rectal tumours is increasingly considered as a non-operative approach, with online-adaptive radiotherapy (oART) supporting this approach by correcting inter-fraction tumour position errors. However, using cone-beam computed tomography (CBCT)-guided oART requires daily target volume delineation by different operators, leading to inter-operator delineation variability and potential dosimetric issues. This study aims to compare and quantify the inter-operator and inter-professional delineation variability of the rectal boost volume on CBCT, including volumes by an automatically delineated oART treatment planning system. Materials and methodsA rectal boost volume, defined as the primary tumour extended to the entire adjacent rectal wall, was delineated on 10 CBCTs from 5 patients by 15 operators: 4 expert radiation oncologists (ROs), 4 radiation therapists (RTTs) and 7 non-expert ROs. These contours were compared between the different professional groups. A comparison to the average volume of the group (ROs, RTTs, or non-expert ROs) with the lowest delineation variability was also performed for each individual volume including the volume automatically generated by an oART treatment planning system. ResultsDelineation variability was the highest in the superior (range: 2.3–6.0 mm), and inferior (2.3–12.4 mm) directions, compared to the left (0.2–4.4 mm), right (0.3–2.0 mm), anterior (0.1–2.9 mm), and posterior (0.5–4.0 mm) directions. Non-expert ROs, RTTs, and automatic oART volume showed similar ranges of delineation errors when compared to the expert ROs’ volume, which was chosen as reference volume since this professional group showed the lowest variability. DiscussionExpert ROs showed consistent results. Other professional groups exhibit similar variability, comparable to the automatic oART volume. Therefore, RTTs could safely perform the rectal boost delineation without non-expert ROs supervision in the absence of expert ROs during CBCT-based oART. Moreover, these findings provide quantitative data to compute accurate margins for the rectal boost planning target volume in a CBCT-guided oART workflow.