Three-Dimensional Multimodality Image Reconstruction as Teaching Tool for Case-based learning among medical postgraduates: a focus on primary pelvic bone Tumour Education.

BACKGROUND: Postgraduate medical education in oncology orthopedics confronts obstacles when instructing on pelvic tumors, primarily due to their intricate anatomy and the limitations of conventional teaching techniques. The employment of Three-dimensional multimodality imaging (3DMMI) can be considered a valuable teaching tool, as it gracefully elucidates the intricacies of pelvic anatomical structures and the interactions between tumors and surrounding tissues through three-dimensional imaging, thereby providing a comprehensive and nuanced perspective. This study aimed to assess the feasibility and effectiveness of incorporating 3DMMI in combination with a Case-Based Learning (CBL) approach for postgraduate education. METHODS: The study encompassed a 10-week course involving 90 surgical postgraduates, focusing on common pelvic tumor diseases. Students were assigned representative clinical cases, and each group created a PowerPoint presentation based on these cases. The core educational content included fundamental knowledge of pelvic anatomy, as well as clinical presentations, radiological features, and treatment principles of common pelvic tumor diseases. The research compared two groups: a traditional CBL group (n = 45) and a 3DMMI-CBL group (n = 45). The 3DMMI-CBL group had access to advanced imaging technology for better visualization. Various evaluations, including image interpretation, theoretical knowledge, and questionnaires, were used to assess the learning outcomes. RESULTS: The 3DMMI-CBL group outperformed the CBL group not only in the imaging diagnosis of common pelvic diseases but also in their mastery of the related theoretical knowledge. Student questionnaires indicated higher scores for the 3DMMI-CBL group in basic pelvic anatomy knowledge (8.08 vs. 6.62, p < 0.01), image interpretation (8.15 vs. 6.69, p < 0.01), learning efficiency (8.07 vs. 7.00, p < 0.01), clinical reasoning (7.57 vs. 6.77, p < 0.01), and learning interest (8.46 vs. 7.00, p < 0.01). Teacher questionnaires revealed that 3DMMI technology enhanced teachers' clinical knowledge, facilitated instruction, and increased overall satisfaction and interest in teaching. CONCLUSION: Our study introduced an enhancement to the conventional Case-Based Learning (CBL) model by incorporating 3DMMI technology for visualizing pelvic anatomy. In contrast to pure CBL, this adaptation improved teacher instruction, substantially heightened student engagement, ignited greater interest in learning, and boosted overall efficiency, ultimately leading to positive learning outcomes. Consequently, our study demonstrated the potential feasibility and acceptability of the 3DMMI-CBL teaching method for postgraduates in pelvic bone tumor education.

Clinician survey of current global practice for sarcoma surveillance following resection of primary retroperitoneal, abdominal, and pelvic sarcoma.

INTRODUCTION: - Postoperative surveillance following resection of primary retroperitoneal, abdominal, and pelvic sarcoma (RPS) is standard of care in international sarcoma centres and has rapidly evolved without an evidence base to become highly intensive and prolonged. This clinician survey aims to capture a global, contemporary snapshot of international guidelines used to inform sarcoma surveillance following resection of primary RPS. MATERIALS AND METHODS: - Between July 2022 and March 2023, an online, anonymous, clinician survey to assess the current duration, imaging intervals and imaging modalities used for postoperative surveillance following resection of primary RPS was distributed among clinicians working at centres which are members of the TransAtlantic Australasian Retroperitoneal Working Group (TARPSWG). RESULTS: - Responses were received from 58 different TARPSWG centres. The majority of centres use institutional guidelines to guide surveillance intensity (n = 43, 74%) and the surveillance imaging modality (n = 39, 67%) used. For surveillance intensity and imaging modality, institutional guidelines are partially or entirely based on international guidelines in 81% (n = 47) and 78% (n = 45) of centres, respectively. Commonly used imaging modalities are contrast-enhanced CT abdomen-pelvis (n = 51, 88%) for abdominal surveillance and non-contrast enhanced CT (n = 25, 43%) for chest surveillance. Imaging intervals, timing of de-escalation of imaging frequency and total duration of surveillance for low-grade and high-grade RPS are reported. CONCLUSION: - This global survey among TARPSWG members demonstrates the heterogeneity in sarcoma surveillance strategies worldwide and emphasises the need for a randomised controlled trial to provide an evidence base for the optimal surveillance schedule following primary resection of RPS.

Value of contrast-enhanced ultrasound in deep angiomyxoma using a biplane transrectal probe: A case report.

BACKGROUND: Deep angiomyxoma (DAM) is a very rare tumor type. Magnetic resonance imaging (MRI) is considered the best imaging modality for diagnosing DAM. Computed tomography (CT) is used mainly to assess the invasion range of DAM. The value of ultrasonography in the diagnosis of DAM is still controversial. Through a literature review, we summarized the current state of ultrasonic examination for DAM and reported for the first time the contrast-enhanced ultrasound (CEUS) features of DAM seen using a biplane transrectal probe. CASE SUMMARY: A 37-year-old woman presented with a sacrococcygeal mass that had gradually increased in size over the previous 6 mo. MRI and CT examinations failed to allow a definite diagnosis to be made. Transperineal core needle biopsy (CNB) guided by transrectal ultrasound and CEUS was suggested after a multidisciplinary discussion. Grayscale ultrasound of the lesion showed a layered appearance with alternating hyperechoic and hypoechoic patterns. Transrectal CEUS showed a laminated distribution of the contrast agent that was consistent with the layered appearance of the tumor on grayscale ultrasound. We performed transperineal CNB of the enhanced area inside the tumor under transrectal CEUS guidance and finally made a definitive diagnosis of DAM through histopathology. The patient underwent laparoscopic-assisted transabdominal surgery combined with transperineal surgery for large pelvic tumor resection and pelvic floor peritoneal reconstruction. No recurrence or metastasis was found at the nine-month follow-up. CONCLUSION: Transrectal CEUS can show the layered perfusion characteristics of the contrast agent, guiding subsequent transperineal CNB of the enhanced area within the DAM.

Feasibility of tracked ultrasound registration for pelvic-abdominal tumor navigation: a patient study.

PURPOSE: Surgical navigation techniques can guide surgeons in localizing pelvic-abdominal malignancies. For abdominal navigation, accurate patient registration is crucial and is generally performed using an intra-operative cone-beam CT (CBCT). However, this method causes 15-min surgical preparation workflow interruption and radiation exposure, and more importantly, it cannot be repeated during surgery to compensate for large patient movement. As an alternative, the accuracy and feasibility of tracked ultrasound (US) registration are assessed in this patient study. METHODS: Patients scheduled for surgical navigation during laparotomy of pelvic-abdominal malignancies were prospectively included. In the operating room, two percutaneous tracked US scans of the pelvic bone were acquired: one in supine and one in Trendelenburg patient position. Postoperatively, the bone surface was semiautomatically segmented from US images and registered to the bone surface on the preoperative CT scan. The US registration accuracy was computed using the CBCT registration as a reference and acquisition times were compared. Additionally, both US measurements were compared to quantify the registration error caused by patient movement into Trendelenburg. RESULTS: In total, 18 patients were included and analyzed. US registration resulted in a mean surface registration error of 1.2 ± 0.2 mm and a mean target registration error of 3.3 ± 1.4 mm. US acquisitions were 4 × faster than the CBCT scans (two-sample t-test P < 0.05) and could even be performed during standard patient preparation before skin incision. Patient repositioning in Trendelenburg caused a mean target registration error of 7.7 ± 3.3 mm, mainly in cranial direction. CONCLUSION: US registration based on the pelvic bone is accurate, fast and feasible for surgical navigation. Further optimization of the bone segmentation algorithm will allow for real-time registration in the clinical workflow. In the end, this would allow intra-operative US registration to correct for large patient movement. TRIAL REGISTRATION: This study is registered in ClinicalTrials.gov (NCT05637359).

Dose estimation for cone-beam computed tomography in image-guided radiation therapy for pelvic cancer using adult mesh-type reference computational phantoms.

The use of cone-beam computed tomography (CBCT) is expanding owing to its installation in linear accelerators for radiation therapy, and the imaging dose induced by this system has become the center of attention. Here, the dose to patients caused by the CBCT imager was investigated. Organ doses and effective doses for male and female mesh-type reference computational phantoms (MRCPs) and pelvis CBCT mode, routinely used for pelvic irradiation, were estimated using the Particle and Heavy Ion Transport Code System. The simulation results were confirmed based on the point-dose measurements. The estimated organ doses for male MRCPs with/without raised arms and for female MRCPs with/without raised arms were 0.00286-35.6 mGy, 0.00286-35.1 mGy, 0.00933-39.5 mGy, and 0.00931-39.0 mGy, respectively. The anticipated effective doses for male MRCPs with/without raised arms and female MRCPs with/without raised arms irradiated by pelvis CBCT mode were 4.25 mSv, 4.16 mSv, 7.66 mSv, and 7.48 mSv, respectively. The results of this study will be useful for patients who undergo image-guided radiotherapy with CBCT. However, because this study only covered one type of cancer with one type of imager, and image quality was not considered, more studies should be conducted to estimate the radiation dose from imaging devices in radiation therapy.

Custom designed and 3D-printed titanium pelvic implants for acetabular reconstruction after tumour resection.

BACKGROUND: Reconstructive procedure following resection of large pelvic tumours around the hip joint remains a complex challenge. METHODS: This study presents a retrospective case series of patients presenting with benign or malignant pelvic tumour for which an internal hemipelvectomy including the hip joint and subsequent reconstruction with a custom designed 3-dimensional printed titanium pelvic implant (3DPPI) has been performed between August 2013 and January 2018. RESULTS: 15 consecutive patients with a median age of 33.9 years (IQR 26.4-72.2) and a median BMI of 20.7 kg/m2 (IQR 19.0-33.3) were reviewed after median follow-up of 33.8 months (IQR 24.0-78.1). The majority of patients presented with a malignant tumour as their principal diagnosis (n = 13, 86.7%). The median surgical time was 5.5 hours (IQR 4.5-8.5) and median peri-operative blood loss was 5000 ml (IQR 2000-10000). The median MSTS score at follow-up was 63.3% (IQR 51.7-86.7%). The median NRS in rest was 0.0 (IQR 0.0-5.0), the median NRS during activity was 2.0 (IQR 0.5-7.0) and the median HOOS-PS was 76.6% (IQR 67.9-91.0). 4 patients had implant-specific complications (n = 4, 26.6%); 1 hip dislocation (Henderson type 1a), 3 structural complications (type 3a), 1 deep infection (type 4a) and 1 local tumour recurrence (type 5b). At follow-up, 4 out of 15 implants were classified as a failure, resulting in an implant survival rate of 73.3%. CONCLUSIONS: Acceptable peri-operative outcomes, functional results, complication rates and short-term implant survival can be achieved in a cohort of complex patients undergoing 3DPPI reconstruction after hemipelvectomy including the acetabulum.

Clinical efficacy and safety analysis of CT-guided 125I implantation in the treatment of recurrent or metastatic pelvic malignant tumor.

PURPOSE: This study was conducted to evaluate the clinical efficacy and safety of computed tomography (CT)-guided 125I implantation in the treatment of recurrent or metastatic pelvic malignant tumor. METHODS AND MATERIALS: This retrospective study analyzed the data of 30 patients with recurrent and metastatic pelvic malignant tumor who were treated with CT-guided 125I implantation between January 2016 and December 2020. Disease control rate, objective remission rate, overall survival (OS), pain relief rate, quality of life score, and complications were evaluated after the followup. RESULTS: Median followup was 20.1 (7-30) months. Disease control rate was 86.67% at 6 months. Objective response rates at 1, 3, and 6 months were 36.67%, 60%, and 56.67%, respectively. OS rates at 12 and 24 months were 76.67% (23/30) and 33.33% (10/30), respectively. Progression-free survival rates at 12 and 24 months were 63.33% (19/30) and 33.33% (10/30), respectively. Postoperative pain relief rate was 86.67% (26/30). There were no major bleeding, pelvic abscess, intestinal fistula, intestinal perforation, and other serious complications. CONCLUSIONS: CT-guided 125I seed implantation in the treatment of patients with pelvic malignant tumor is a simple operation and less traumatic and can improve patients' quality of life and reduce tumor load.

Angiomixoma agresivo pélvico: reporte de caso y revisión / Aggressive pelvic angiomyxoma: case report and revision / Angiomixoma agressivo: relato de caso e revisão

El angiomixoma agresivo pélvico es un tumor de partes blandas extremadamente raro, del cual se han reportado alrededor de 350 casos hasta la fecha. A continuación se reporta el caso clínico de una paciente que presentó dicho tumor y se describe el proceso diagnóstico y su tratamiento quirúrgico. Por otro lado, se realiza una breve revisión de la literatura disponible hasta el momento sobre el tema.

Aggressive pelvic angiomyxoma is an extremely rare soft tissue tumor, of which around 350 cases have been reported to date. This article aims at reporting the case of a patient presenting said tumor, as well as describing its diagnostic approach and its surgical treatment. On the other hand, it aims at briefly reviewing the available literature on the subject.

O angiomixoma pélvico agressivo é um tumor extremamente raro dos tecidos moles, tendo sido descritos até à data cerca de 350 casos. Relatamos o caso de uma doente que apresentava este tumor e descrevemos o processo de diagnóstico e tratamento cirúrgico. É também feita uma breve revisão da literatura disponível até à data sobre o assunto.

Fisher discriminant model based on LASSO logistic regression for computed tomography imaging diagnosis of pelvic rhabdomyosarcoma in children.

Computed tomography (CT) has been widely used for the diagnosis of pelvic rhabdomyosarcoma (RMS) in children. However, it is difficult to differentiate pelvic RMS from other pelvic malignancies. This study aimed to analyze and select CT features by using least absolute shrinkage and selection operator (LASSO) logistic regression and established a Fisher discriminant analysis (FDA) model for the quantitative diagnosis of pediatric pelvic RMS. A total of 121 pediatric patients who were diagnosed with pelvic neoplasms were included in this study. The patients were assigned to an RMS group (n = 36) and a non-RMS group (n = 85) according to the pathological results. LASSO logistic regression was used to select characteristic features, and an FDA model was constructed for quantitative diagnosis. Leave-one-out cross-validation and receiver operating characteristic (ROC) curve analysis were used to evaluate the diagnostic ability of the FDA model. Six characteristic variables were selected by LASSO logistic regression, all of which were CT morphological features. Using these CT features, the following diagnostic models were established: (RMS group)[Formula: see text]; (Non-RMS group)[Formula: see text], where [Formula: see text], [Formula: see text], … and [Formula: see text] are lower than normal muscle density (1 = yes; 0 = no), multinodular fusion (1 = yes; 0 = no), enhancement at surrounding blood vessels (1 = yes; 0 = no), heterogeneous progressive centripetal enhancement (1 = yes; 0 = no), ring enhancement (1 = yes; 0 = no), and hemorrhage (1 = yes; 0 = no), respectively. The calculated area under the ROC curve (AUC) of the model was 0.992 (0.982-1.000), with a sensitivity of 94.4%, a specificity of 96.5%, and an accuracy of 95.9%. The calculated sensitivity, specificity and accuracy values were consistent with those from cross-validation. An FDA model based on the CT morphological features of pelvic RMS was established and could provide an easy and efficient method for the diagnosis and differential diagnosis of pelvic RMS in children.

Lumbosacral plexopathy caused by the perineural spread of pelvic malignancies: clinical aspects and imaging patterns.

BACKGROUND: Perineural spread (PNS) of tumors from pelvic malignancies is a rare phenomenon but constitutes an important differential diagnosis of lumbosacral plexopathy (LSP). Herein, we describe the clinical and imaging features of patients with LSP due to PNS of pelvic malignancies along with a literature review. METHODS: We retrospectively reviewed 9 cases of LSP caused by PNS of pelvic malignancy between January 2006 and August 2021, and all clinical and imaging parameters were recorded in detail. Clinical symptoms and signs of patients were described and listed in the order in which they occurred. The results of imaging test were analyzed to describe specific findings in LSP caused by PNS. RESULTS: This study enrolled nine adult patients (mean age, 50.1 years). Two cases initially presented as LSP and were later diagnosed with pelvic malignancy. Pain in the perianal or inguinal area preceded pain at the extremities in six patients. Neurogenic bladder or bowel symptoms developed in five patients. On the magnetic resonance imaging (MRI), the S1-S2 spinal nerve was most commonly involved, and S1 myotome weakness was more prominent in six patients than the other myotomes. One patient had an intradural extension. 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) showed abnormal signal intensity in six patients. No abnormality in 18F-FDG PET/CT was detected in the nervous structures in one patient. Only four patients survived until the last follow-up visit. CONCLUSIONS: Though rare, physicians should always keep in mind the possibility of LSP due to the PNS in patients with pelvic malignancy. Thorough physical examination and history taking could provide clues for diagnosis. Pelvic MRI and 18F-FDG-PET/CT should be considered for patients with LSP to rule out neoplastic LSP.

A spectrum of findings on computed tomography in paediatric abdominal and pelvic tumours in a Ghanaian teaching hospital.

Objectives: To review the Computed Tomography( CT )features of pediatric oncological patients with abdominal and pelvic tumours and correlate these findings with their histopathological diagnosis. Design: This was a retrospective cross-sectional facility-based study. Setting: This study was conducted in the Pediatric Oncology Unit and Radiology Department of the Korle Bu Teaching Hospital. Participants: Fifty-six pediatric oncology patients with contrast-enhanced abdominal and pelvic CT scans. Data Collection: The abdominal and pelvic CT scans findings, patient biodata, and histopathology reports of oncology patients over four years were reviewed. Statistical analysis: Simple descriptive statistics using frequency distribution, percentages, means, and standard deviation were used to describe the various variables and presented tables. Results: The four commonest tumours were nephroblastoma, neuroblastoma, lymphoma, and hepatoblastoma. The mean age at diagnosis was 4.8 years, with a slightly higher male predominance. The majority of the tumours were extremely large at presentation. Overall, the CT - histopathology concordance was 79.2%. Conclusion: Abdominal and pelvic CT scans play an important role in the diagnostic workup of pediatric malignancies by ensuring early and accurate diagnosis of these tumours. Funding: None declared.

Adult sacrococcygeal teratoma: A review.

Sacrococcygeal teratomas (SCT) in adults are extremely rare, and most SCTs are located either mainly outside the pelvis, with a small number of intrapelvic components, or mostly in the pelvis (types III and IV). The etiology of teratomas remains unknown. Most teratomas are benign, and approximately 1 to 2% of teratomas undergo malignant transformation, including squamous cell carcinoma, adenocarcinoma, sarcoma, and other malignancies. Most SCTs grow insidiously, and their symptoms are not easily detected in the early stages. Some cases may only be discovered through physical examination or compression symptoms when the tumor reaches a detectable size. Computed tomography and magnetic resonance imaging have high detection rates for presacral space-occupying lesions and can provide imaging details with guiding significance for the selection of surgical methods. Surgical resection is the preferred treatment option for SCT and can determine the pathological type. Common sacrococcygeal malignancies are mainly immature teratomas and mature teratomas. When the presence of malignant components is confirmed, the treatment model should be adjusted according to pathological type.

Rare Mesenchymal Tumors of the Pelvis: Imaging and Pathologic Correlation.

Most pelvic tumors originate from the organs. Less commonly, tumors can arise from the various anatomic pelvic compartments and are comprised of mesenchymal tissue: muscles, connective tissue, vessels, lymphatics, and fat. Among some of the rarer entities are benign tumors (eg, angiomyxoma, cellular angiofibroma, and desmoid fibromatosis), malignant tumors (eg, sarcoma), and tumors that can manifest as benign or malignant (eg, solitary fibrous tumor or nerve sheath tumor). Because these tumors are uncommon and often manifest with nonspecific clinical features, imaging (usually MRI) is an initial step in the evaluation. Radiologists interpreting these images are asked to help narrow the differential diagnosis and assess the likelihood of malignancy for treatment planning. Thus, the MRI report should include the imaging features that would indicate the underlying tissue histology for pathologic diagnosis as well as a description of the anatomic extent and pattern of growth. The authors describe multiple locally aggressive benign and malignant mesenchymal tumors and highlight characteristic clinical and imaging features that enable the radiologist to narrow the differential diagnosis. The anatomic spaces of the pelvis are reviewed with illustrations to aid the radiologist in describing these tumors, which often span multiple pelvic compartments. Tumor appearance at T2-weighted, diffusion-weighted, and postcontrast MRI is summarized and illustrated with correlation at CT or fluorodeoxyglucose PET/CT, when available. MRI features that correspond to specific types of tissue (eg, myxoid, fibrous, or vascular) are highlighted and correlated with images from pathologic evaluation. Online supplemental material is available for this article. ©RSNA, 2021.

Atypical Metastases in the Abdomen and Pelvis From Biochemically Recurrent Prostate Cancer: 11C-Choline PET/CT With Multimodality Correlation.

PET with targeted radiotracers has become integral to mapping the location and burden of recurrent disease in patients with biochemical recurrence (BCR) of prostate cancer (PCa). PET with 11C-choline is part of the National Comprehensive Cancer Network and European Association of Urology guidelines for evaluation of BCR. With advances in PET technology, increasing use of targeted radiotracers, and improved survival of patients with BCR because of novel therapeutics, atypical sites of metastases are being increasingly encountered, challenging the conventional view that prostate cancer rarely metastasizes beyond bones or lymph nodes. The purpose of this article is to describe such atypical metastases in the abdomen and pelvis on 11C-choline PET (including metastases to the liver, pancreas, genital tract, urinary tract, peritoneum, abdominal wall, and perineural spread) and to present multimodality imaging features and relevant imaging pitfalls. Given atypical metastases' inconsistent relationship with the serum PSA level and the nonspecific presenting symptoms, atypical metastases are often first detected on imaging. Awareness of their imaging features is important because their detection affects clinical management, patient counseling, prognosis, and clinical trial eligibility. Such awareness is particularly critical because the role of radiologists in the imaging and management of BCR will continue to increase given the expanding regulatory approvals of other targeted and theranostic radiotracers.

Intracardiac extension of intravenous leiomyomatosis in a patient with vascular pelvic tumor and prior hysterectomy: A case report.

Uterine leiomyoma (UL) is the most common benign smooth muscle tumour of the premenopausal women. Rarely it shows malignant behaviour by metastasizing through the pelvic veins into systemic veins, inferior vena cava (IVC), there it is termed as intravenous leiomyomatosis (IVL). IVL may restrict itself within the IVC or it may extend into right heart chambers reaching up to pulmonary arteries. Here we report a case of single staged excision of intracardiac(IC) extension of IVL of a 45 -year -old premenopausal women, who have undergone abdominal hysterectomy five years ago, with the complaints of shortness of breath aggravated on bending forward for the past two years.

Differentiating renal pelvic cancer from renal cell carcinoma with 18-fluorodeoxyglucose positron emission tomography-computed tomography.

BACKGROUND: The differential diagnosis of pelvis renalis cancer (PRC) from renal cell cancer (RCC) is difficult. Because of that, in this study, we compared the standardized uptake value (SUV) with positron emission tomography-computed tomography (PET-CT) of the RCC and PRC. METHODS: Twenty-one patients (12 males, 9 females; age range: 33-74 years; mean age ± standard deviation [SD]: 57.14 ± 17.6) with suspected primary renal cell cancer as Group 1 and 8 patients (6 male, 2 female; age range, 61-81; mean age ± SD, 71.5 ± 5.65) with suspected renal pelvis cancer as Group 2 detected by conventional imaging techniques (CT, magnetic resonance [MR] imaging, ultrasound, intravenous urogram, CT urography, MR urography) underwent fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT imaging between August 2010 and October 2012. RESULTS: Mean age is 57.14 (33-74) years in Group 1 and 71.5 (61-81) years in Group 2, respectively. The mean maximum SUV (SUVmax) value was 4.6 ± 2.1 in RCC group and 16.6 ± 6.9 in PRC group. At the 18-FDG PET/CT scanning, SUVmax value higher in patients with PRC than in the patients with RCC. It was statistically different (P < 0.001). CONCLUSION: We suggested that PET/CT can be used for the differential diagnosis of renal pelvis tumor and RCC. However, further studies with larger patient number are needed to confirm our suggestion. To clarify the mechanisms of underlying these differences, molecular advanced molecular studies are needed.

Prevalence of Malignancy on Contrast-Enhanced Computed Tomography of the Abdomen and Pelvis in Patients With Unexplained, Unintentional Weight Loss.

OBJECTIVE: The aim of the study was to evaluate the prevalence of malignancy on contrast-enhanced computed tomography (CT) of the abdomen and pelvis in patients with unexplained, unintentional weight loss (UUWL). METHODS: This is a retrospective review of 999 adult outpatient contrast-enhanced CT of the abdomen and pelvis for UUWL. Patients were stratified into 2 groups: (1) weight loss only (WLO, n = 222) and (2) UUWL with additional symptoms (UUWL+, n = 777). χ2 test was performed to compare malignancy detection rate in the WLO and UUWL+ groups. RESULTS: Prevalence of malignancy was 5.3% (95% confidence interval [CI], 4.2%-7.1%; 55 of 999). Prevalence of malignancy in the WLO group was 2.3% (95% CI, 0.7%-5.2%; 5 of 222), lower than the prevalence of 6.2% (95% CI, 4.6%-8.1%; 48 of 777) in the UUWL+ group (P = 0.02). Prevalence of malignancy was lower in patients younger than 60 years in all patients and in the UUWL+ subgroup (P < 0.01 in both cases). CONCLUSIONS: There is low prevalence of malignancy on contrast-enhanced CT of the abdomen and pelvis in patients with UUWL, particularly in younger patients and those without additional symptoms.