CT, MRI and PET imaging in peritoneal malignancy

Migrating pseudolipoma of Glisson's capsule: A case report

Pseudolipoma of Glisson's capsule is a rare, benign subcapsular liver lesion that typically occurs in older adult men. It comprises degenerated fat tissue that likely originates from detached mesothelial appendages or degenerated liver lipomas. We report the case of a 58-year-old female patient with a gastric malignant tumor after admission. No lesions were found in the liver capsule before surgery. During postoperative reviews from 2015 to 2018, new dense, fatty lesions were found under the liver capsule, and highly unusually, the lesions moved under the liver capsule over time. To the best of our knowledge, only 1 other case has been reported of a pseudolipoma of Glisson's capsule that migrated over time. This supports the hypothesis that migrating mesothelial attachments form Glisson capsule pseudolipomas. This case report aims to review liver capsule anatomy, explain why the liver is particularly susceptible to this phenomenon, and present information to aid the diagnosis of fat-containing hepatic lesions by providing a unique perspective on certain pathologies affecting the liver.

Dual-energy CT quantitative parameters to evaluate occult peritoneal metastasis in advanced gastric cancer preoperatively

PURPOSE

To explore whether dual-energy CT (DECT) quantitative parameters could provide analytic value for the diagnosis of patients with occult peritoneal metastasis (OPM) in advanced gastric cancer preoperatively.

MATERIALS AND METHODS

This retrospective study included 219 patients with advanced gastric cancer and DECT scans. The patient's clinical data and DECT related iodine concentration (IC) parameters and effective atomic number (Zeff) were collated and analyzed among noun-peritoneal metastasis (NPM), OPM and radiologically peritoneal metastasis (RPM) groups. The predictive performance of the DECT parameters was compared with that of the conventional CT features and clinical characteristics through evaluating area under curve of the precision-recall (AUC-PR), F1 score, balanced accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

RESULTS

Borrmann IV type diagnosed on CT and serum tumor indicator CA125 index were statistically different between the NPM and OPM groups. DECT parameters included IC, normalized IC (NIC), and Zeff of PM group were lower than the NPM group. The DECT predictive nomogram combined three independent DECT parameters produced a better diagnostic performance than the conventional CT feature Borrmann IV type and serum CA125 index in AUC-PR with 0.884 vs 0.368 vs 0.189, but similar to the combined indicator which was based on the DECT parameters, the conventional CT feature, and serum CA125 index in AUC-PR with 0.884 vs 0.918.

CONCLUSION

The lower quantitative NIC, IC ratio, and Zeff on DECT was associated with peritoneal metastasis in advanced gastric cancer and was promising to identify patients with OPM noninvasively.

The Significance of the Morphological Appearance of Peritoneal Lesions on Imaging in Patients With Peritoneal Malignancies-A Report From Phase 1 of the PRECINCT Study

BACKGROUND AND AIM

This is a report from Phase 1 of the prospective, observational, PRECINCT (Pattern of peritoneal dissemination and REsponse to systemic Chemotherapy IN Common and uncommon peritoneal Tumours) study, in which we studied the incidence of disease at pathological evaluation in different morphological appearances of peritoneal malignancies (PM) on imaging.

METHODS

Radiological findings were captured in a specific format that included a description of the morphological appearance of PM and a correlation performed with pathological findings.

RESULTS

In 630 patients enroled at seven centres (September 2022-December 2023), 24 morphological terms were used. Among prespecified terms (N = 8 used in 6350 [92.2%] regions), scalloping was pathologically positive in 93.5%, confluent disease in 78.8%, tumour nodules in 69.6%, thickening in 66.1%, infiltration in 56.3%. Among unspecified appearances (N = 16) for 540 (7.8%) regions, 'enhancement' was positive in 41.5%, micronodules in 65.3% and nodularity in 60.2%. Hierarchal clustering placed gastric cancer and rare tumours together and colorectal cancer, ovarian cancer and peritoneal mesothelioma in one cluster.

CONCLUSIONS

The incidence of disease at pathological evaluation for most morphological appearances was high (> 50%). Morphological description should be provided in routine radiology reports. A set of standardized terms with their description should be developed by a consensus among experienced radiologists.

Non-Coding RNAs in Peritoneal Carcinomatosis: From Bench to Bedside

Peritoneal carcinomatosis represents an advanced stage of tumors within the peritoneal cavity. Once considered an incurable terminal cancer metastasis, contemporary medicine is on the hunt for certain potentially curative options alongside the present day's palliative disease management. However, for most patients, peritoneal carcinomatosis continues to pose a fatal late-stage prognosis with a grim future outlook. Over the past two decades, non-coding RNAs have garnered significant attention due to their undeniable significance in regulating cellular processes across all levels. Disruption of the intricate regulation led by non-coding RNAs has been demonstrated to have a substantial impact on various human diseases, particularly in cancer, including solid tumors originating from the organs of the peritoneal cavity. This review aims to offer a comprehensive overview of the current state of knowledge in the under-researched field of peritoneal carcinomatosis, focusing specifically on the role of non-coding RNAs in the development of this condition and delineating potential avenues for future research.

The Peritoneum: Anatomy, Pathologic Findings, and Patterns of Disease Spread

Disease spread in the abdomen and pelvis generally occurs in a predictable pattern in relation to anatomic landmarks and fascial planes. Anatomically, the abdominopelvic cavity is subdivided into several smaller spaces or compartments by key ligaments and fascial planes. The abdominal cavity has been traditionally divided into peritoneal, retroperitoneal, and pelvic extraperitoneal spaces. Recently, more clinically relevant classifications have evolved. Many pathologic conditions affect the abdominal cavity, including traumatic, inflammatory, infectious, and neoplastic processes. These abnormalities can extend beyond their sites of origin through various pathways. Identifying the origin of a disease process is the first step in formulating a differential diagnosis and ultimately reaching a final diagnosis. Pathologic conditions differ in terms of pathways of disease spread. For example, simple fluid tracks along fascial planes, respecting anatomic boundaries, while fluid from acute necrotizing pancreatitis can destroy fascial planes, resulting in transfascial spread without regard for anatomic landmarks. Furthermore, neoplastic processes can spread through multiple pathways, with a propensity for spread to noncontiguous sites. When the origin of a disease process is not readily apparent, recognizing the spread pattern can allow the radiologist to work backward and ultimately arrive at the site or source of pathogenesis. As such, a cohesive understanding of the peritoneal anatomy, the typical organ or site of origin for a disease process, and the corresponding pattern of disease spread is critical not only for initial diagnosis but also for establishing a road map for staging, anticipating further disease spread, guiding search patterns and report checklists, determining prognosis, and tailoring appropriate follow-up imaging studies. ©RSNA, 2024 Supplemental material is available for this article.

Colorectal cancer

Despite decreased incidence rates in average-age onset patients in high-income economies, colorectal cancer is the third most diagnosed cancer in the world, with increasing rates in emerging economies. Furthermore, early onset colorectal cancer (age ≤50 years) is of increasing concern globally. Over the past decade, research advances have increased biological knowledge, treatment options, and overall survival rates. The increase in life expectancy is attributed to an increase in effective systemic therapy, improved treatment selection, and expanded locoregional surgical options. Ongoing developments are focused on the role of sphincter preservation, precision oncology for molecular alterations, use of circulating tumour DNA, analysis of the gut microbiome, as well as the role of locoregional strategies for colorectal cancer liver metastases. This overview is to provide a general multidisciplinary perspective of clinical advances in colorectal cancer.

The role of multimodality imaging in the selection and management of patients treated with cytoreductive surgery and HIPEC

Cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) is the mainstay of potentially curative surgical treatment for malignancies that have spread to peritoneal surfaces. This surgical procedure is however associated with high morbidity and appropriate patient selection and planning is therefore essential. Available multimodality imaging techniques include CT with oral and intravenous contrast, MRI including use of dedicated peritoneal protocol and FDG-PET/CT. These used with the correct technique, read by specialist radiologists and discussed under the auspices of a dedicated multidisciplinary team, can help to improve outcomes. We demonstrate that imaging not only provides information about peritoneal disease burden but more importantly want to shift the reader's focus to disease distribution. Our examples highlight how imaging helps avoid futile surgery by identifying patients with disease in unfavourable sites and show the strength and limitations of the various imaging modalities. We share how MR imaging can help identify multifocal and often occult sites including widespread miliary disease. Our examples provide a comprehensive overview demonstrating how imaging can help plan surgery by identifying patients who may need splenic vaccinations, counselling for stoma, egg harvesting and input from surgeons with other specialist expertise greatly increasing likelihood of achieving complete cytoreduction.

Intraperitoneal chemotherapy for peritoneal metastases of gastric origin: a systematic review and meta-analysis

BACKGROUND

Gastric cancer with peritoneal metastases is associated with a dismal prognosis. Normothermic catheter-based intraperitoneal chemotherapy and normothermic pressurized intraperitoneal aerosol chemotherapy (PIPAC) are methods to deliver chemotherapy intraperitoneally leading to higher intraperitoneal concentrations of cytotoxic drugs compared to intravenous administration. We reviewed the effectiveness and safety of different methods of palliative intraperitoneal chemotherapy.

METHODS

Embase, MEDLINE, Web of Science and Cochrane were searched for articles studying the use of repeated administration of palliative intraperitoneal chemotherapy in patients with gastric cancer and peritoneal metastases, published up to January 2024. The primary outcome was overall survival.

RESULTS

Twenty-three studies were included, representing a total of 999 patients. The pooled median overall survival was 14.5 months. The pooled hazard ratio of the two RCTs using intraperitoneal paclitaxel and docetaxel favoured the intraperitoneal chemotherapy arm. The median overall survival of intraperitoneal paclitaxel, intraperitoneal docetaxel and PIPAC with cisplatin and doxorubicin were respectively 18.4 months, 13.2 months and 9.0 months. All treatment methods had a relatively safe toxicity profile. Conversion surgery after completion of intraperitoneal therapy was performed in 16% of the patients.

CONCLUSIONS

Repeated intraperitoneal chemotherapy, regardless of method of administration, is safe for patients with gastric cancer and peritoneal metastases. Conversion surgery after completion of the intraperitoneal chemotherapy is possible in a subset of patients.

Targeting interleukin-6 as a treatment approach for peritoneal carcinomatosis

Peritoneal carcinomatosis (PC) is a complex manifestation of abdominal cancers, with a poor prognosis and limited treatment options. Recent work identifying high concentrations of the cytokine interleukin-6 (IL-6) and its soluble receptor (sIL-6-Rα) in the peritoneal cavity of patients with PC has highlighted this pathway as an emerging potential therapeutic target. This review article provides a comprehensive overview of the current understanding of the potential role of IL-6 in the development and progression of PC. We discuss mechansims by which the IL-6 pathway may contribute to peritoneal tumor dissemination, mesothelial adhesion and invasion, stromal invasion and proliferation, and immune response modulation. Finally, we review the prospects for targeting the IL-6 pathway in the treatment of PC, focusing on common sites of origin, including ovarian, gastric, pancreatic, colorectal and appendiceal cancer, and mesothelioma.

Imaging of Peritoneal Metastases in Ovarian Cancer Using MDCT, MRI, and FDG PET/CT: A Systematic Review and Meta-Analysis

This review aims to compare the diagnostic performance of multidetector CT (MDCT), MRI, including diffusion-weighted imaging, and FDG PET/CT in the detection of peritoneal metastases (PMs) in ovarian cancer (OC). A comprehensive search was performed for articles published from 2000 to February 2023. The inclusion criteria were the following: diagnosis/suspicion of PMs in patients with ovarian/fallopian/primary peritoneal cancer; initial staging or suspicion of recurrence; MDCT, MRI and/or FDG PET/CT performed for the detection of PMs; population of at least 10 patients; surgical results, histopathologic analysis, and/or radiologic follow-up, used as reference standard; and per-patient and per-region data and data for calculating sensitivity and specificity reported. In total, 33 studies were assessed, including 487 women with OC and PMs. On a per-patient basis, MRI (p = 0.03) and FDG PET/CT (p < 0.01) had higher sensitivity compared to MDCT. MRI and PET/CT had comparable sensitivities (p = 0.84). On a per-lesion analysis, no differences in sensitivity estimates were noted between MDCT and MRI (p = 0.25), MDCT and FDG PET/CT (p = 0.68), and MRI and FDG PET/CT (p = 0.35). Based on our results, FDG PET/CT and MRI are the preferred imaging modalities for the detection of PMs in OC. However, the value of FDG PET/CT and MRI compared to MDCT needs to be determined. Future research to address the limitations of the existing studies and the need for standardization and to explore the cost-effectiveness of the three imaging modalities is required.

Peritoneal Carcinomatosis of Malignant Gynecological Origin: A Systematic Review of Imaging Assessment

This systematic review, conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, aims to comprehensively assess the current state of the art of imaging modalities for the evaluation of peritoneal carcinomatosis arising from malignant gynecological origins, with a focus on ovarian and endometrial cancers. A systematic search of relevant databases was performed, adhering to predetermined inclusion and exclusion criteria. Studies reporting the use of computed tomography (CT), magnetic resonance imaging (MRI), fluorodeoxyglucose (FDG) positron emission tomography (PET), PET/CT, and PET/MRI in the assessment of peritoneal carcinomatosis from gynecological malignancies were included. The review encompasses an overview of selected studies, highlighting the strengths and limitations of each imaging modality in diagnosing and characterizing peritoneal carcinomatosis. Overall, a wide variability in the reported accuracy of different imaging techniques emerges from literature, mainly due to the type of the study, technical issues, and patient characteristics. Although a meta-analysis could not be performed due to a scarcity of data, this systematic review provides valuable insights into the several imaging approaches used in peritoneal carcinomatosis of gynecological origin. The findings aim to inform clinical decision making and guide future research endeavors in this critical aspect of gynecological oncology.

Unveiling the Metabolic Maze: FDG PET/CT Findings in Peritoneal Carcinomatosis - A Case Series

Peritoneal carcinomatosis (PC), the spread of cancer cells in the peritoneum, is a significant concern in advanced gastrointestinal and gynecological cancers. This case series includes findings on the appearance and pattern of PC on 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT). The primary sources of peritoneal dissemination are direct invasion from abdominal or pelvic tumors and metastatic spread from distant tumors. The accurate preoperative diagnosis and quantification of PC play a vital role in determining the appropriate treatment approach, with a particular emphasis on surgical planning. Several imaging modalities have been employed in preoperative evaluation, such as computed tomography (CT), magnetic resonance imaging (MRI), and 18F-FDG PET/CT. Among these modalities, 18F-FDG PET/CT has demonstrated improved anatomical localization and accurate information about the nature of pathological findings. The case series showcases four cases that illustrate the imaging characteristics of PC on FDG PET/CT. FDG PET/CT plays a vital role in diagnosing and assessing PC, aiding in its detection, staging, and treatment planning. It surpasses conventional imaging techniques in identifying and characterizing lesions and detecting the primary tumor site in cases where its location is unknown. Furthermore, FDG PET/CT additionally assists in evaluating treatment response and monitoring disease progression, providing insights into treatment effectiveness and guiding patient management decisions.

Complete clinical remission of malignant peritoneal mesothelioma with systemic pemetrexed and bevacizumab in a patient with a BAP1 mutation

Malignant peritoneal mesothelioma (MPeM) is a rare malignancy with historically poor prognosis. Recent research has started to reveal increasingly prevalent genetic mutations seen in this malignancy. Here, we report a case of complete clinical remission of unresectable, metastatic MPeM with systemic chemotherapy. Immunohistochemistry of our patient's malignant cytology sample showed loss of Breast Cancer Gene 1-associated protein-1 expression (BAP1). The patient had synchronous diagnoses of primary squamous cell carcinoma of the anus, benign schwannoma and meningioma. Following the completion of 18 cycles of pemetrexed and bevacizumab, the patient has remained in clinical remission for 8 months. We examine the unusual susceptibility of unresectable MPeM to systemic chemotherapy and attribute susceptibility to the molecular milieu created by mutations in multiple DNA repair pathways. We encourage increased testing for and analysis of mutations in DNA repair pathways to improve future treatment outcomes in this rare malignancy.

UK trial of pressurised intraperitoneal aerosolised chemotherapy (PIPAC) with oxaliplatin for colorectal cancer peritoneal metastases (NCT03868228)

Objectives

This is the first UK trial of pressurised intraperitoneal aerosolised chemotherapy (PIPAC) for colorectal cancer peritoneal metastases. This trial aimed to assess the impact of PIPAC in combination with standard of care systemic treatment on: progression free survival (PFS); quality of life (QoL); and short-term complications. In addition, this trial set out to demonstrate that PIPAC can be performed safely in operating theatres within a National Health Service (NHS) setting.

Methods

Single-centre clinical trial with prospective data collection for patients undergoing 8-weekly PIPAC with oxaliplatin at 92 mg/m2 from January 2019 till January 2022. Progression free survival was assessed using peritoneal carcinomatosis index (PCI) by CT scans and laparoscopy. Quality of life was assessed by EORTC QLQ-C30 questionnaire. Adverse events were recorded using CTCAE.

Results

Five patients underwent a total of ten PIPAC administrations (median 2, range 1-4). Median PFS was 6.0 months. QoL was maintained across repeat PIPAC procedures but a decrease in social functioning and increased fatigue were evident. Three incidences of grade 3 adverse events occurred but PIPAC was well tolerated.

Conclusions

The presented data demonstrates that PIPAC is feasible and can be safely delivered within the NHS for patients with colorectal cancer peritoneal metastases, but caution must also be exercised given a risk of adverse events. Systemic chemotherapy can be safely administered at a different unit to the PIPAC procedure if both groups have clear lines of communication and timely data sharing.

The Role of Staging Laparoscopy for Intrahepatic Cholangiocarcinoma: A Snapshot of the Current Literature

Background: Accurate preoperative workup is crucial to identify patients with intrahepatic cholangiocarcinoma (IHC) who would have truly benefit from liver resection, avoiding it in patients with advanced disease or distant metastases. Staging laparoscopy (SL) may prevent unnecessary laparotomies in those patients with otherwise resectable disease, but evidence of its efficacy is scarce and inconclusive. We aimed to aggregate the available evidence dealing with this specific field of research to produce a snapshot of the current knowledge systematically reviewing the inherent literature. Methods: PubMed/Medline, EMBASE, and Web of Sciences electronic databases were queried through December 2022. Inclusion criteria considered all articles reporting data about the role of SL for patients with a diagnosis of IHC. The main outcomes were as follows: overall yield and sensitivity of SL. Results: A total of 5 studies including 119 patients met the inclusion criteria and were included in the analysis. Overall, the yield of SL was 19.6% (11.4%-36%), and the sensitivity was 65.2% (55%-71%). Conclusions: The role of SL for patients with a preoperative diagnosis of IHC remains unclear. The lack of criteria and indications to perform SL for IHC raises the need for international consensus on this specific field of research.

The Role of Prophylactic and Adjuvant Hyperthermic Intraperitoneal Chemotherapy (HIPEC) in Prevention of Peritoneal Metastases in Advanced Colorectal Cancer

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a locoregional therapy that may be combined with cytoreductive surgery (CRS) to treat patients with colorectal cancer and peritoneal metastases (PM). In recent years, three randomized controlled trials (RCTs) have investigated the role of prophylactic or adjuvant HIPEC in preventing the development of PM in patients with high-risk colorectal cancer: PROPHYLOCHIP and COLOPEC evaluated adjuvant HIPEC, and HIPECT4 studied concurrent HIPEC and CRS. Although PROPHYLOCHIP and COLOPEC were negative trials, a great deal may be learned from their methodology, outcome measures, and patient selection criteria. HIPECT4 is the first RCT to show a clinical benefit of HIPEC in high-risk T4 colorectal cancer, demonstrating improved locoregional disease control with the addition of HIPEC to CRS with no increase in the rate of complications. This review critically examines the strengths and limitations of each major trial and discusses their potential impact on the practice of HIPEC. Several additional ongoing clinical trials also seek to investigate the role of HIPEC in preventing PM in advanced colorectal cancer.

Head-to-Head Comparison of FDG and Radiolabeled FAPI PET: A Systematic Review of the Literature

FAPI-based radiopharmaceuticals are a novel class of tracers, mainly used for PET imaging, which have demonstrated several advantages over [18F]FDG, especially in the case of low-grade or well-differentiated tumors. We conducted this systematic review to evaluate all the studies where a head-to-head comparison had been performed to explore the potential utility of FAPI tracers in clinical practice. FAPI-based radiopharmaceuticals have shown promising results globally, in particular in detecting peritoneal carcinomatosis, but studies with wider populations are needed to better understand all the advantages of these new radiopharmaceuticals.

Unravelling Peritoneal Carcinomatosis Using Cross-Sectional Imaging Modalities

Peritoneal carcinomatosis (PC) refers to malignant epithelial cells that spread to the peritoneum, principally from abdominal malignancies. Until recently, PC prognosis has been considered ill-fated, with palliative therapies serving as the only treatment option. New locoregional treatments are changing the outcome of PC, and imaging modalities have a critical role in early diagnosis and disease staging, determining treatment decision making strategies. The aim of this review is to provide a practical approach for detecting and characterizing peritoneal deposits in cross-sectional imaging modalities, taking into account their appearances, including the secondary complications, the anatomical characteristics of the peritoneal cavity, together with the differential diagnosis with other benign and malignant peritoneal conditions. Among the cross-sectional imaging modalities, computed tomography (CT) is widely available and fast; however, magnetic resonance (MR) performs better in terms of sensitivity (92% vs. 68%), due to its higher contrast resolution. The appearance of peritoneal deposits on CT and MR mainly depends on the primary tumour histology; in case of unknown primary tumour (3-5% of cases), their behaviour at imaging may provide insights into the tumour origin. The timepoint of tumour evolution, previous or ongoing treatments, and the peritoneal spaces in which they occur also play an important role in determining the appearance of peritoneal deposits. Thus, knowledge of peritoneal anatomy and fluid circulation is essential in the detection and characterisation of peritoneal deposits. Several benign and malignant conditions show similar imaging features that overlap those of PC, making differential diagnosis challenging. Knowledge of peritoneal anatomy and primary tumour histology is crucial, but one must also consider clinical history, laboratory findings, and previous imaging examinations to achieve a correct diagnosis. In conclusion, to correctly diagnose PC in cross-sectional imaging modalities, knowledge of peritoneal anatomy and peritoneal fluid flow characteristics are mandatory. Peritoneal deposit features reflect the primary tumour characteristics, and this specificity may be helpful in its identification when it is unknown. Moreover, several benign and malignant peritoneal conditions may mimic PC, which need to be considered even in oncologic patients.

Primary and secondary tumors of the peritoneum: key imaging features and differential diagnosis with surgical and pathological correlation

Peritoneal malignancies represent a diagnostic challenge for abdominal radiologists, oncologists, surgeons and pathologists in multidisciplinary teams, who must address their differential diagnosis, staging and treatment. In this article, we explain the pathophysiology of these processes and lay out the role of different imaging techniques in their evaluation. Then, we review the clinical and epidemiological aspects, the main radiological features and the therapeutic approaches for each primary and secondary peritoneal neoplasm, with surgical and pathological correlation. We further describe other rare peritoneal tumors of uncertain origin and a variety of entities that may mimic peritoneal malignancy. Finally, we summarize the key imaging findings of each peritoneal neoplasm to facilitate an accurate differential diagnosis that may impact patient management.Clinical relevance statementImaging plays an essential role in the evaluation of peritoneal malignancies, assessing their extension, detecting unfavorable sites of involvement and facilitating an accurate differential diagnosis, helping to choose the best therapeutic approach.

A Novel Diagnostic Imaging Method for the Early Detection of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, with a survival rate of less than 10% [...].

Targeting Oncometabolites in Peritoneal Cancers: Preclinical Insights and Therapeutic Strategies

Peritoneal cancers present significant clinical challenges with poor prognosis. Understanding the role of cancer cell metabolism and cancer-promoting metabolites in peritoneal cancers can provide new insights into the mechanisms that drive tumor progression and can identify novel therapeutic targets and biomarkers for early detection, prognosis, and treatment response. Cancer cells dynamically reprogram their metabolism to facilitate tumor growth and overcome metabolic stress, with cancer-promoting metabolites such as kynurenines, lactate, and sphingosine-1-phosphate promoting cell proliferation, angiogenesis, and immune evasion. Targeting cancer-promoting metabolites could also lead to the development of effective combinatorial and adjuvant therapies involving metabolic inhibitors for the treatment of peritoneal cancers. With the observed metabolomic heterogeneity in cancer patients, defining peritoneal cancer metabolome and cancer-promoting metabolites holds great promise for improving outcomes for patients with peritoneal tumors and advancing the field of precision cancer medicine. This review provides an overview of the metabolic signatures of peritoneal cancer cells, explores the role of cancer-promoting metabolites as potential therapeutic targets, and discusses the implications for advancing precision cancer medicine in peritoneal cancers.

European expert panel consensus on the clinical management of BRAFV600E-mutant metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) is a heterogenous disease caused by various genetic alterations. The BRAF^V600E mutation occurs in approximately 8-12% of patients and is characterised by an aggressive clinical course and poor prognosis. Here we review the current knowledge on BRAF^V600E-mutant mCRC and provide a series of consensus statements on its clinical management. The treatment landscape for BRAF^V600E-mutant mCRC has changed greatly due to the emergence of molecular targeted therapies (including BRAF inhibitors) and immune checkpoint inhibitors. A scientific literature search identified available data on molecular testing, treatments, and clinical monitoring of patients with BRAF^V600E-mutant mCRC. Consensus statements were discussed and developed by a European expert panel. This manuscript provides consensus management guidance for different clinical presentations of BRAF^V600E-mutant mCRC and makes recommendations regarding treatment sequencing choices. To guide appropriate clinical management and treatment decisions for mCRC patients, tumour tissue analysis for DNA mismatch repair/microsatellite status and, at a minimum, KRAS, NRAS, and BRAF mutational status is mandatory at the time of diagnosis. Finally, we discuss the rapidly evolving treatment landscape for BRAF^V600E-mutant mCRC and define priorities for the development of novel therapeutic strategies that are needed to improve patient outcomes.

Diagnosis and treatment of peritoneal carcinomatosis - a comprehensive overview

Peritoneal carcinomatosis, which is the most common malignant process of the peritoneal cavity, originates mostly from colorectal, gastric, and gynaecological malignancies. The differential diagnosis is broad and covers primary peritoneal malignancies, as well as many benign disorders such as endometriosis, and inflammatory and infectious diseases. Peritoneal implants tend to locate in the areas of the physiological stasis of the peritoneal fluid: pelvic peritoneal reflections, right and left paracolic gutters, superior part of the sigmoid mesocolon, ileocolic area, and the right subdiaphragmatic space. The 3 most common imaging findings are ascites, nodular implants, and infiltration of the peritoneal fatty tissue. Several imaging modalities may be applied in patients with peritoneal carcinomatosis. Ultrasound has low sensitivity and specificity, and therefore plays only a marginal role. Computed tomography is the method of choice, due to its availability, cost-effectiveness, and relatively high sensitivity. The sensitivity of magnetic resonance imaging depends on the size of peritoneal implants - in cases of implants larger than 10 mm is comparable to CT. Some studies suggest that PET/CT may be the most sensitive method, yet its usefulness in everyday practice is controversial. The Peritoneal Carcinomatosis Index (PCI) is a scale used to assess the tumour burden in the peritoneum and may serve as a communication tool between clinicians and radiologists. The imaging findings may influence the surgeon's decision on performing cytoreductive surgery, which may be followed by intraperitoneal chemotherapy (HIPEC or EPIC procedures). The introduction of these therapeutic methods has significantly improved the life expectancy of patients with peritoneal carcinomatosis.

Patterns and Timing of Recurrence following CRS and HIPEC in Colorectal Cancer Peritoneal Metastasis

INTRODUCTION

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (CRS/HIPEC) is an established treatment of Colorectal Peritoneal Metastases (CRPM). This study aims to determine the timing and patterns of recurrent disease on imaging following complete CRS/HIPEC.

METHODS

Retrospective analysis of a national peritoneal tumour service database identified CRPM patients with complete CRS/HIPEC(CC0) from 2005 to-2018. Patients with<2 years follow-up or and those where post-operative histology from the CRS/HIPEC procedure did not confirm CRPM from their original colorectal cancer were excluded. Time to recurrence was measured from surgery to first radiologically illustrated recurrence. CT was the primary modality used, supplemented by PET-CT or MRI if required. Outcomes of interest were survival data (including overall survival (OS), disease-free survival (DFS) and peritoneal-recurrence free survival (PRFS)), timing and patterns of recurrent disease.

RESULTS

146 of the 176 patients identified were eligible for inclusion. Median OS for all study patients was 45.2 months (95% CI 38-53 months), median DFS was 11.7 months (95% CI 9-14 months), and median PRFS was 25.2 months (95% CI 14.7-30 months). Recurrent disease was seen in 112 cases (77%), radiologically classified as intraperitoneal in 50 patients (44%), single site systemic in 21 patients (19%) and multi-site in 41 patients (37%). CT detection rate for disease recurrence was 88%. Subgroup analyses showed that PCI ≥12, positive nodal primary disease and synchronous peritoneal disease were associated with worse outcomes.

CONCLUSION

Patients selected for CRS/HIPEC for CRPM have an OS > 45 months, with the majority recurring systemically within a year. Peritoneal recurrence is a later event after several years. Surveillance programs in this group should be most intensive in the first 2 years after surgery, using CT with oral and intravenous contrast.

Role and usefulness of mr imaging in the assessment of peritoneal carcinomatosis

BACKGROUND

For many years, peritoneal carcinomatosis (PC) entitled poor prognosis until the development of the cytoreductive surgery technique associated with hyperthermic intraperitoneal chemotherapy. Imaging of peritoneal carcinomatosis plays an essential role in the diagnosis and management of the patients being considered for cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC).

MAIN BODY

The key role of imaging in patients with peritoneal malignancy is to aid surgical decision making. A standardized peritoneal magnetic resonance (MR) imaging protocol, including T2-weighted fat suppressed, diffusion-weighted and gadolinium-enhanced sequences, allows to detect small peritoneal tumours that are often missed on other imaging. A systematic approach to MR imaging and a close collaboration between the radiologist and the oncologic surgeon are key elements for an accurate evaluation of candidate patients for CRS and HIPEC.

CONCLUSION

MR imaging provides a powerful tool for accurate preoperative imaging in patients considered for curative surgery and assists the surgeon in evaluating patients for CRS and HIPEC.

CT imaging features of fat stranding in cats and dogs with abdominal disorder

BACKGROUND

Fat stranding is a non-specific finding of an increased fat attenuation on computed tomography (CT) images. Fat stranding is used for detecting the underlying lesion in humans.

OBJECTIVES

To assess the clinical significance of fat stranding on CT images for identifying the underlying cause in dogs and cats.

METHODS

In this retrospective study, the incidence, location, extent, distribution, and pattern of fat stranding were assessed on CT studies obtained from 134 cases.

RESULTS

Fat stranding was found in 38% (51/134) of all cases and in 35% (37/107) of tumors, which was significantly higher in malignant tumors (44%) than benign tumors (12%). Moreover, fat stranding was found in more than two areas in malignant tumors (16/33) and in a single area in benign tumors (4/4). In inflammation, fat stranding was demonstrated in 54% (7/13) in a single area (7/7) as a focal distribution (6/7). In trauma, fat stranding was revealed in 50% (7/14) and most were in multiple areas (6/7). Regardless of the etiologies, fat stranding was always around the underlying lesion and a reticular pattern was the most common presentation. Logistic regression analysis revealed that multiple areas (p = 0.040) of fat stranding and a reticulonodular pattern (p = 0.022) are the significant predictors of malignant tumor.

CONCLUSIONS

These findings indicated that CT fat stranding can be used as a clue for identifying the underlying lesion and can be useful for narrowing the differential list based on the extent and pattern.

Prospective Comparison of the Performance of MRI Versus CT in the Detection and Evaluation of Peritoneal Surface Malignancies

Background: The performance of MRI versus CT in the detection and evaluation of peritoneal surface malignancies (PSM) remains unclear in the current literature. Our study is the first prospective study in an Asian center comparing the two imaging modalities, validated against intra-operative findings. Methods: A total of 36 patients with PSM eligible for CRS-HIPEC underwent both MRI and CT scans up to 6 weeks before the operation. The scans were assessed for the presence and distribution of PSM and scored using the peritoneal cancer index (PCI), which were compared against PCI determined at surgery. Results: Both MRI and CT were 100% sensitive and specific in detecting the overall presence of PSM. Across all peritoneal regions, the sensitivity and specificity for PSM detection was 49.1% and 93.0% for MRI, compared to 47.8% and 95.1% for CT (p = 0.76). MRI was more sensitive than CT for small bowel disease, although the difference did not reach statistical significance. Comparing PCI on imaging with intra-operative PCI, the mean difference was found to be −3.4 ± 5.4 (p < 0.01) for MRI, and −3.9 ± 4.1 (p < 0.01) for CT. The correlation between imaging and intra-operative PCI was poor, with a concordance coefficient of 0.76 and 0.79 for MRI and CT, respectively. Within individual peritoneal regions, there was also poor agreement between imaging and intra-operative PCI for both modalities, other than in regions 1 and 3. Conclusion: MRI and CT are comparable in the detection and evaluation of PSM. While sensitive in the overall detection of PSM, they are likely to underestimate the true disease burden.

Peritoneal malignancy: anatomy, pathophysiology and an update on modern day imaging

With increasing subspecialised experience in radical cytoreductive surgery and intra-abdominal chemotherapy for peritoneal malignancy, outcomes have improved significantly in selected patients. The surgery and the treatment regimens are radical and therefore correct patient selection is critical. The radiologist plays a central role in this process by estimating, as precisely as possible, the pre-treatment disease burden. Because of the nature of the disease process, accurate staging is not an easy task. Tumour deposits may be very small and in locations where they are very difficult to detect. It must be acknowledged that no form of modern day imaging has the capability of detecting the smallest peritoneal nodules, which may only be visible to direct inspection or histopathological evaluation. Nonetheless, it behoves the radiologist to be as exact and precise as possible in the reporting of this disease process. This is both to select patients who are likely to benefit from radical treatment, and just as importantly, to identify patients who are unlikely to achieve adequate cytoreductive outcomes. In this review, we outline the patterns of spread of disease and the anatomic basis for this, as well as the essential aspects of reporting abdominal studies in this patient group. We provide an evidence-based update on the relative strengths and limitations of our available multimodality imaging techniques namely CT, MRI and positron emission tomography/CT.

Prostate-Specific Membrane Antigen (PSMA) Expression in Tumor-Associated Neovasculature Is an Independent Prognostic Marker in Patients with Ovarian Cancer

Prostate-specific membrane antigen (PSMA) is present in the tumor-associated neovasculature of many cancer types. Current data in ovarian cancer are limited and controversial; thus, the aim of this study was to investigate PSMA expression in a larger and homogenous patient cohort. This might lead to further studies investigating the use of imaging and therapeutic modalities targeting PSMA. Eighty patients with advanced stage high-grade serous ovarian cancers were included. Using immunohistochemistry, PSMA and CD31, a marker for endothelial cells, were examined in whole tissue sections. Percentage and intensity of PSMA expression were determined in the neovasculature. Expression levels were correlated with clinicopathological parameters and survival. Low (≤10%), medium (20–80%), and high (≥90%) PSMA expression was found in 14, 46, and 20 ovarian cancer samples, respectively. PSMA expression was confined to tumor-associated neovasculature and significantly correlated with progression-free (HR 2.24, 95% CI 1.32–3.82, p = 0.003) and overall survival (HR 2.73, 95% CI 1.41–5.29, p = 0.003) in multivariate models, considering age, FIGO stage, and residual disease. This is the first study showing a clinical relevance for PSMA in patients with ovarian cancer. PSMA was detected in the vast majority of cancer samples and showed an impact on survival.

Positive Versus Neutral Oral Contrast Material for Detection of Malignant Deposits in Intraabdominal Nonsolid Organs on CT

Background: Data are limited regarding utility of positive oral contrast material for peritoneal tumor detection on CT. Objective: To compare positive versus neutral oral contrast material for detection of malignant deposits in nonsolid intraabdominal organs on CT. Methods: This retrospective study included 265 patients (133 men, 132 women; median age, 61 years) who underwent an abdominopelvic CT examination where the report did not suggest presence of malignant deposits and subsequent CT examination within 6 months where the report indicated at least one unequivocal malignant deposit. Examinations used positive (iohexol; n=100) or neutral (water; n=165) oral agents. A radiologist reviewed images to assess whether the deposits were visible (despite clinical reports indicating no deposits) on unblinded comparison with the follow-up examinations; identified deposits were assigned to one of seven intraabdominal compartments. The radiologist also assessed adequacy of bowel filling with oral contrast material. Two additional radiologists independently reviewed examinations in blinded fashion for malignant deposits. NPV was assessed of clinical CT reports and blinded retrospective readings for detection of malignant deposits visible on unblinded comparison with follow-up examinations. Results: Unblinded review identified malignant deposits in 58.1% (154/265) of examinations. In per-patient analysis of clinical reports, NPV for malignant deposits was higher for examinations with adequate bowel filling with positive oral contrast material [65.8% (25/38)] than for examinations with inadequate bowel filling with positive oral contrast material [45.2% (28/62]], p=.07) or with neutral oral contrast material regardless of bowel filling adequacy [35.2% (58/165), p=.002]. In per-compartment analysis of blinded interpretations, NPV was higher for examinations with adequate and inadequate bowel filling with positive oral contrast material than for examinations with neutral oral contrast regardless of bowel filling adequacy [reader 1: 94.7% (234/247) and 92.5% (382/413) vs 88.3% (947/1072), both p=.045; reader 2: 93.1% (228/245) and 91.6% (361/394) vs 85.9% (939/1093), both p=.01]. Conclusion: CT has suboptimal NPV for malignant deposits in intraabdominal nonsolid organs. Compared to neutral material, positive oral contrast material improves detection, particularly with adequate bowel filling. Clinical Impact: Optimization of bowel preparation for oncologic CT may help avoid potentially severe clinical consequences of missed malignant deposits.

Primary peritoneal serous carcinoma: a primer for radiologists

Primary peritoneal serous carcinoma (PPSC) is a rare primary peritoneal tumor characterized by a unique range of clinical features and imaging findings. Though it shares many clinical, histologic, and imaging features with serous ovarian carcinoma, it remains a distinct clinical entity. Although less common than its primary ovarian counterpart, PPSC is characterized by a prognosis that is often equally poor with presentations common in late stages of disease. Key imaging modalities used in the evaluation of PPSC include ultrasound, CT, MRI, and PET/CT. For radiologists, an understanding of the pertinent imaging findings, pathologic correlations, and clinical features of PPSC is essential for arriving at the correct diagnosis and guiding the subsequent appropriate management of this complex malignancy.

Primary and metastatic peritoneal surface malignancies

Peritoneal surface malignancies comprise a heterogeneous group of primary tumours, including peritoneal mesothelioma, and peritoneal metastases of other tumours, including ovarian, gastric, colorectal, appendicular or pancreatic cancers. The pathophysiology of peritoneal malignancy is complex and not fully understood. The two main hypotheses are the transformation of mesothelial cells (peritoneal primary tumour) and shedding of cells from a primary tumour with implantation of cells in the peritoneal cavity (peritoneal metastasis). Diagnosis is challenging and often requires modern imaging and interventional techniques, including surgical exploration. In the past decade, new treatments and multimodal strategies helped to improve patient survival and quality of life and the premise that peritoneal malignancies are fatal diseases has been dismissed as management strategies, including complete cytoreductive surgery embedded in perioperative systemic chemotherapy, can provide cure in selected patients. Furthermore, intraperitoneal chemotherapy has become an important part of combination treatments. Improving locoregional treatment delivery to enhance penetration to tumour nodules and reduce systemic uptake is one of the most active research areas. The current main challenges involve not only offering the best treatment option and developing intraperitoneal therapies that are equivalent to current systemic therapies but also defining the optimal treatment sequence according to primary tumour, disease extent and patient preferences. New imaging modalities, less invasive surgery, nanomedicines and targeted therapies are the basis for a new era of intraperitoneal therapy and are beginning to show encouraging outcomes.

Multidetector computed tomography in diagnosing peritoneal metastases in ovarian carcinoma

Multidetector computed tomography (MDCT) of the abdomen is currently the imaging examination of choice for the staging and follow-up of ovarian carcinoma (OC). Peritoneal metastases (PMs) represent the most common pathway for the metastatic spread of OC. MDCT scanners, due to several advantages-including increased volume coverage, reduced scanning time, acquisition of thin slices and creation of multiplanar reformations, and three-dimensional reconstructions-provide useful information regarding the early and accurate detection of PMs. Detailed mapping of peritoneal carcinomatosis is feasible, with improved detection of sub-centimeter peritoneal implants and thorough evaluation of curved peritoneal surfaces.

Radiomics based on multisequence magnetic resonance imaging for the preoperative prediction of peritoneal metastasis in ovarian cancer

OBJECTIVES

To develop a radiomics signature based on multisequence magnetic resonance imaging (MRI) to preoperatively predict peritoneal metastasis (PM) in ovarian cancer (OC).

METHODS

Eighty-nine patients with OC were divided into a training cohort including patients (n = 54) with a single lesion and a validation cohort including patients (n = 35) with bilateral lesions. Radiomics features were extracted from the T2-weighted images (T2WIs), fat-suppressed T2WIs, multi-b-value diffusion-weighted images (DWIs), and corresponding parametric maps. A radiomics signature and nomogram incorporating the radiomics signature and clinical predictors were developed and validated on the training and validation cohorts, respectively.

RESULTS

The radiomics signature generated by 6 selected features showed a favorable discriminatory ability to predict PM in OC with an area under the curve (AUC) of 0.963 in the training cohort and an AUC of 0.928 in the validation cohort. The nomogram, comprising the radiomics signature, pelvic fluid, and CA-125 level, showed more favorable discrimination with an AUC of 0.969 in the training cohort and 0.944 in the validation cohort. Net reclassification index with values of 0.548 in the training cohort and 0.500 in the validation cohort.

CONCLUSION

Radiomics signature based on multisequence MRI serves as an effective quantitative approach to predict PM in OC patients. A nomogram of radiomics signature and clinical predictors could further improve the prediction ability of PM in patients with OC.

KEY POINTS

• Multisequence MRI-based radiomics showed a favorable discriminatory ability to predict PM in OC. • The nomogram incorporating the radiomics signature and clinical predictors was clinically useful to preoperatively predict PM in patients with OC.

Nanotechnology for Cancer Imaging: Advances, Challenges, and Clinical Opportunities

Nanoparticle (NP) imaging applications have the potential to improve cancer diagnostics, therapeutics, and treatment management. In biomedical research and clinical practice, NPs can serve as labels or labeled carriers for monitoring drug delivery or serve as imaging agents for enhanced imaging contrast, as well as providing improved signal sensitivity and specificity for in vivo imaging of molecular and cellular processes. These qualities offer exciting opportunities for NP-based imaging agents to address current limitations in oncologic imaging. Despite substantial advancements in NP design and development, very few NP-based imaging agents have translated into clinics within the past 5 years. This review highlights some promising NP-enabled imaging techniques and their potential to address current clinical cancer imaging limitations. Although most examples provided herein are from the preclinical space, discussed imaging solutions could offer unique in vivo tools to solve biologic questions, improve cancer treatment effectiveness, and inspire clinical translation innovation to improve patient care. Keywords: Molecular Imaging-Cancer, Molecular Imaging-Nanoparticles, Molecular Imaging-Optical Imaging, Metastases, Oncology, Surgery, Treatment Effects.

Micro-Biopsy Forceps in the Assessment of Peritoneal Carcinomatosis: A Possible New Indication?

Peritoneal carcinomatosis (PC) is defined as a metastatic involvement of the peritoneum by several other primary sites and it is characterized by a marked worsening of prognosis, with limited treatment opportunities. Subsequently, PC should be ruled out before any invasive treatment is administered. A new through-the-needle micro-biopsy forceps (MF) was recently introduced that permits micro-histology cores. In this case series, we evaluated the feasibility of MF in the assessment of PC to complete patient diagnostic work-ups. Five consecutive patients referred for endoscopic ultrasound staging were sampled using MF. Sampling was feasible in all patients with a technical success of 100%. No adverse events were reported in any cases. This technique was feasible and safe with a technical success rate of 100%. It permitted sampling of peritoneal irregularity, obtained high-quality tissue fragments in all cases, and enabled an additional assessment, i.e., immunohistochemical staining.

Additional Value of Integrated 18F-FDG PET/MRI for Evaluating Biliary Tract Cancer: Comparison with Contrast-Enhanced CT

Objective

To evaluate the value of ¹⁸F-fluorodeoxyglucose PET/MRI added to contrast-enhanced CT (CECT) in initial staging, assessment of resectability, and postoperative follow-up of biliary tract cancer.

Materials and Methods

This retrospective study included 100 patients (initial workup [n = 65] and postoperative follow-up [n = 35]) who had undergone PET/MRI and CECT for bile duct or gallbladder lesions between January 2013 and March 2020. Two radiologists independently reviewed the CECT imaging set and CECT plus PET/MRI set to determine the likelihood of malignancy, local and overall resectability, and distant metastasis in the initial workup group, and local recurrence and distant metastasis in the follow-up group. Diagnostic performances of the two imaging sets were compared using clinical-surgical-pathologic findings as standards of reference.

Results

The diagnostic performance of CECT significantly improved after the addition of PET/MRI for liver metastasis (area under the receiver operating characteristic curve [A_z]: 0.77 vs. 0.91 [p = 0.027] for reviewer 1; 0.76 vs. 0.92 [p = 0.021] for reviewer 2), lymph node metastasis (0.73 vs. 0.92 [p = 0.004]; 0.81 vs. 0.92 [p = 0.023]), and overall resectability (0.79 vs. 0.92 [p = 0.007]; 0.82 vs. 0.94 [p = 0.021]) in the initial workup group. In the follow-up group, the diagnostic performance of CECT plus PET/MRI was significantly higher than that of CECT imaging for local recurrence (0.81 vs. 1.00 [p = 0.029]; 0.82 vs. 0.94 [p = 0.045]).

Conclusion

PET/MRI may add value to CECT in patients with biliary tract cancer both in the initial workup for staging and determination of overall resectability and in follow-up for local recurrence.

Diagnostic value of diffusion-weighted imaging/magnetic resonance imaging for peritoneal metastasis from malignant tumor: A systematic review and meta-analysis

BACKGROUND

Previous meta-analyses examined either multiple tools for the diagnosis of peritoneal metastases (PMs), but not diffusion-weighted imaging (DWI), or included only 1 tumor type. This study aimed to determine the summary diagnostic value of DWI/magnetic resonance imaging in determining PMs originating from various tumors.

METHODS

PubMed, Embase, and Cochrane library were searched for available papers up to 2019/12. Pooled estimates for sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and accuracy were calculated using random-effects models.

RESULTS

Ten studies were included and could be used to calculate the pooled sensitivity and specificity. The pooled sensitivity of DWI for PMs was 89% (95% confidence interval [CI]: 83%-93%). The pooled specificity was 86% (95% CI: 79%-91%). When considering only the retrospective studies, the pooled sensitivity of DWI for PMs was 85% (95% CI: 81%-89%). The pooled specificity was 84% (95% CI: 72%-92%). When considering only the studies about gastrointestinal tumors, the pooled sensitivity of DWI for PMs was 97% (95% CI: 68%-100%). The pooled specificity was 86% (95% CI: 69%-95%). No publication bias was observed (P = dd.27).

CONCLUSION

DWI magnetic resonance imaging is highly sensitive and specific for the detection of PMs from various abdominal cancers.

Carcinoma of unknown primary with hepatic metastases: a need of judicious and contemplative diagnostic algorithm

Carcinoma of Unknown Primary presenting primarily as hepatic metastases encompasses a dismal subgroup of tumors with a median survival of 5.9 months. Adenocarcinoma is the most common histological subtype identified upon biopsy and the primary tumor remains undetectable in the majority of cases despite extensive workup. It is important to have a validated and standardized algorithm to follow these tumors to avoid unnecessary tests, as the wishes and health status of the patient represent the principal concerns. The purpose of this paper is to briefly review the current literature on carcinoma of unknown primary with hepatic metastases and propose a standardized diagnostic approach.

Photodynamic Diagnosis and Therapy for Peritoneal Carcinomatosis from Gastrointestinal Cancers: Status, Opportunities, and Challenges

Selective accumulation of a photosensitizer and the subsequent response in only the light-irradiated target are advantages of photodynamic diagnosis and therapy. The limited depth of the therapeutic effect is a positive characteristic when treating surface malignancies, such as peritoneal carcinomatosis. For photodynamic diagnosis (PDD), adjunctive use of aminolevulinic acid- protoporphyrin IX-guided fluorescence imaging detects cancer nodules, which would have been missed during assessment using white light visualization only. Furthermore, since few side effects have been reported, this has the potential to become a vital component of diagnostic laparoscopy. A variety of photosensitizers have been examined for photodynamic therapy (PDT), and treatment protocols are heterogeneous in terms of photosensitizer type and dose, photosensitizer-light time interval, and light source wavelength, dose, and dose rate. Although several studies have suggested that PDT has favorable effects in peritoneal carcinomatosis, clinical trials in more homogenous patient groups are required to identify the true benefits. In addition, major complications, such as bowel perforation and capillary leak syndrome, need to be reduced. In the long term, PDD and PDT are likely to be successful therapeutic options for patients with peritoneal carcinomatosis, with several options to optimize the photosensitizer and light delivery parameters to improve safety and efficacy.

MR Imaging of the Perihepatic Space

The perihepatic space is frequently involved in a spectrum of diseases, including intrahepatic lesions extending to the liver capsule and disease conditions involving adjacent organs extending to the perihepatic space or spreading thanks to the communication from intraperitoneal or extraperitoneal sites through the hepatic ligaments. Lesions resulting from the dissemination of peritoneal processes may also affect the perihepatic space. Here we discuss how to assess the perihepatic origin of a lesion and describe the magnetic resonance imaging (MRI) features of normal structures and fluids that may be abnormally located in the perihepatic space. We then review and illustrate the MRI findings present in cases of perihepatic infectious, tumor-related, and miscellaneous conditions. Finally, we highlight the value of MRI over computed tomography.

Greater Omentum Imaging-Reporting and Data System: establishing the grade of benign and malignant lesions of the greater omentum using ultrasonography

OBJECTIVE

To establish Greater Omentum Imaging-Reporting and Data System (GOI-RADS) to evaluate the possibility of omental diseases being malignant.

METHOD

A retrospective analysis was made of 883 patients who had undergone biopsy of the greater omentum in our center from October 2009 to October 2019. Twelve parameters of ultrasonographic images were evaluated, and the odds ratio of each group calculated. We assigned scores for the direct signs (omental echo, omental structure, and omental nodules) and indirect signs (separation of ascites, echo of ascites, mesenteric lymph nodes, and thickening of parietal peritoneum) of omental lesions. We created an omental score (OS) for each patient and receiver operating characteristic (ROC) curve to analyze its effectiveness in the differential diagnosis of benign and malignant omental diseases.

RESULTS

The OS was divided into ≤5, 6, 7, 8, 9, 10, 11, 12, 13, and ≥ 14 points, and the malignant rate was 0, 1.85, 5.56, 30.36, 37.25, 87.72, 96.72, 98.28, 99.08, and 100%, respectively. The area under the ROC curve (AUC) was 0.976. When taking 10 points as the cutoff value to diagnose benign and malignant omental diseases, the sensitivity and specificity was 93.85 and 98.21%, respectively. A grading system was established: grade 1: omental score ≤ 5, malignant rate 0%; grade 2: omental score 6-7, malignant rate ≤ 5.56%; grade 3: omental score 8--9, malignant rate ≤ 37.25%; grade 4: omental score ≥ 10, malignant rate ≥ 87.72.

CONCLUSION

GOI-RADS had high sensitivity and specificity in the differential diagnosis of benign and malignant omental lesions. We believe that GOI-RADS will aid the diagnosis of omental diseases based on objective and accurate interpretation of ultrasound features, and also to promote the ultrasonography of omental diseases in clinical application.

Migrating pseudolipoma of Glisson's capsule

Pseudolipomas of Glisson's capsule are rare benign subcapsular liver lesions that typically affect older men. They are composed of degenerating fat that is thought to originate from a detached epiploic appendage. On Computed Tomographic (CT) imaging, pseudolipomas of Glisson's capsule are well-circumscribed and hypoattenuating compared to the hepatic parenchyma. This case report examines three consecutive CT studies in the same patient that show the pseudolipoma migrating to a hepatic subcapsular location over a period of 4.5 months. To our knowledge, this is the first documented case of a pseudolipoma migrating over time and it supports the hypothesis of a migrating epiploic appendage forming a pseudolipoma of Glisson's capsule. A comprehensive review of relevant literature and a discussion of the presented case are provided.

Diffusion-Weighted Magnetic Resonance Imaging as a Noninvasive Parameter for Differentiating Benign and Malignant Intraperitoneal Collections

Background and Objective: The imaging differentiation of benign from malignant intraperitoneal collections (IPCs) relies on the tumoral morphological modifications of the peritoneum, which are not always advocating for malignancy. We aimed to assess ascitic fluid with the apparent diffusion coefficient (ADC) to determine non-invasive, stand-alone, differentiation criteria for benign and malignant intraperitoneal effusions. Materials and Methods: Sixty-one patients with known IPCs who underwent magnetic resonance examinations for reasons such as tumor staging, undetermined abdominal mass and disease follow up were retrospectively included in this study. All subjects had a final diagnosis of the fluid based on pathological examinations, which were divided into benign (n = 37) and malignant (n = 24) IPCs groups. ADC values were measured separately by two radiologists, and the average values were used for comparing the two groups by consuming the independent samples t-test. The receiver operating characteristic analysis was performed to test the ADC values' diagnostic ability to distinguish malignant from benign collections. Results: The differentiation between benign and malignant IPCs based on ADC values was statistically significant (p = 0.0034). The mean ADC values were higher for the benign (3.543 × 10^-3 mm²/s) than for the malignant group (3.057 × 10^-3 mm²/s). The optimum ADC cutoff point for the diagnosis of malignant ascites was <3.241 × 10^-3 mm²/s, with a sensitivity of 77.78% and a specificity of 80%. Conclusions: ADC represents a noninvasive and reproducible imaging parameter that may help to assess intraperitoneal collections. Although successful in distinguishing malignant from benign IPCs, further research must be conducted in order to certify if the difference in ADC values is a consequence of the physical characteristics of the ascitic fluids or their appurtenance to a certain histopathological group.

Detection of Mesenteric Tumor Using Dynamic Contrast Enhanced MRI

PURPOSE

This study was designed to evaluate the use of a novel imaging technique, dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), for detecting mesenteric peritoneal metastases.

METHODS

Thirty-four patients underwent preoperative conventional MRI, including T1, T2, diffusion-weighted (DWI), and delayed gadolinium MRI, as well as DCE MRI. DCE MRI involved imaging the peritoneal cavity every 9 s for 6 min. DCE images were processed to generate parametric maps of tumor vascularity. Two oncologic surgeons and a radiologist reviewed conventional MRI for all tumor and then later reviewed the conventional MRI plus the DCE parametric maps. Images were reviewed for tumor of the parietal peritoneum, porta hepatis, bowel serosa, upper small bowel mesentery, lower small bowel mesentery, and pelvis. Conventional MRI and DCE + MRI findings were compared to operative and histopathologic reports for tumor detection. PCI scores were calculated for surgery, MRI, and DCE.

RESULTS

Upper mesenteric tumor was present in 21 patients. DCE images showed a sensitivity of 100%, specificity of 92%, and accuracy of 97% compared with conventional MRI sensitivity of 24%, specificity of 93%, and accuracy of 50% (p = 0.006). Lower mesenteric tumor was present in 22 patients. DCE images showed a sensitivity of 100%, specificity of 92%, and accuracy of 97% compared with conventional MRI sensitivity of 45%, specificity of 92%, and accuracy of 62% (p = 0.008). The mean surgical PCI for all 34 patients was 23.4 compared with MRI 20.0 (p = 0.003) and DCE MRI 24.1 (p = 0.26). The addition of the DCE images improved the accuracy of total PCI by > 10% in 16 (0.46) patients. For PCI regions 9-12, the mean surgical PCI was 6.0 compared with MRI 4.8 (p = 0.08) and DCE 6.6 (p = 0.02). The addition of DCE images improved the accuracy of the regional PCI > 10% in 15 (0.43) patients.

CONCLUSIONS

DCE MRI provides a novel contrast tool that improves detection of mesenteric tumor. Depicting small-volume mesenteric tumor is better on DCE MRI compared with conventional MRI.

Staging Laparoscopy in Patients with Intrahepatic Cholangiocarcinoma: Is It Still Useful?

Background

The role of staging laparoscopy in patients with intrahepatic cholangiocarcinoma remains unclear. Despite extensive preoperative imaging, approximately 25% of patients are deemed unresectable at laparotomy due to metastasized disease. The aim of this study was to evaluate the frequency of unresectable disease found at staging laparoscopy and to identify predictors for detecting metastasized intrahepatic cholangiocarcinoma.

Methods

We retrospectively collected records of all patients with intrahepatic cholangiocarcinoma, presenting at our institution from 2008 to 2017. Staging laparoscopy was performed on the suspicion of distant metastases and on indication in larger tumors. The yield and sensitivity of staging laparoscopy was calculated. Reasons for unresectability at staging laparoscopy or laparotomy were recorded.

Results

Among a total of 80 patients with potentially resectable intrahepatic cholangiocarcinoma, 35 patients underwent staging laparoscopy on the suspicion of distant metastases. Unresectable disease was found at staging laparoscopy in 15 patients. Reasons for unresectability were liver metastasis (n = 6), peritoneal metastasis (n = 4), severe cirrhosis (n = 2), locally advanced tumor with satellite lesions (n = 1), and distant lymph node metastasis (n = 2). Considering optimal preoperative imaging, the true yield of staging laparoscopy was 20% (7/35). Two patients did not undergo laparotomy due to progression after staging laparoscopy. Of the remaining 18 patients who underwent laparotomy, 6 patients (30%) had unresectable disease, mostly because of distant metastasis (n = 4).

Conclusions

The role of staging laparoscopy to detect unresectable intrahepatic cholangiocarcinoma is highly dependent on the quality of preoperative imaging. Currently, no accurate selection criteria on imaging exist to select patients with intrahepatic cholangiocarcinoma who potentially benefit from staging laparoscopy.

Diagnostic Laparoscopy and Abdominal Cytology Reliably Detect Peritoneal Metastases in Patients with Urachal Adenocarcinoma

BACKGROUND

Urachal adenocarcinoma (UrAC) is a rare malignancy that can cause peritoneal metastases (PM). Analogous to other enteric malignancies, selected patients with limited PM of UrAC can be treated by cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC).

OBJECTIVE

The aim of this study was to address the value of diagnostic laparoscopy (DLS) and abdominal cytology (ACyt) for the detection and evaluation of the extent of PM in patients with UrAC.

METHODS

A consecutive series of cN0M0 patients with UrAC who underwent DLS with or without ACyt at a tertiary referral center between 2000 and 2018 was assessed. Patients were staged with computed tomography (CT) and/or positron emission tomography (PET)/CT or bone scan. DLS was performed to rule out PM and to evaluate the extent and resectability of PM if seen on imaging. Sensitivity and specificity values were calculated for imaging, DLS, ACyt, and the combination of DLS and ACyt.

RESULTS

Thirty-two patients with UrAC underwent DLS. ACyt was obtained in 19 patients. Four patients had suspicion of PM on imaging. In the 28 patients who were PM-negative on imaging, DLS and ACyt revealed PM in 6 (21%) patients, of whom 5 had macroscopically visible PM; 1 patient had positive ACyt without visible PM. Sensitivity of combined DLS/ACyt for the detection of PM was 91%, with a specificity of 100%, whereas sensitivity of imaging was 36%. DLS correctly predicted resectability in all patients.

CONCLUSION

Combined DLS/ACyt proved an effective tool to detect occult PM and to evaluate the extent of PM to select UrAC patients for possible treatment with CRS/HIPEC.

Two-photon images reveal unique texture features for label-free identification of ovarian cancer peritoneal metastases

For cancer patients, treatment selection fundamentally relies on staging, with "under-staging" considered a common problem. Imaging modalities that can complement conventional white-light laparoscopy are needed to detect more accurately small metastatic lesions in patients undergoing operative cancer care. Biopsies from healthy parietal peritoneum and ovarian peritoneal metastases obtained from 8 patients were imaged employing a two-photon laser scanning microscope to generate collagen-second harmonic generation (SHG) and fluorescence images at 755 nm and 900 nm excitation and 460 ± 20 nm and 525 ± 25 nm emission. Forty-one images were analyzed by automated image processing algorithms and statistical textural analysis techniques, namely gray level co-occurrence matrices. Two textural features (contrast and correlation) were employed to describe the spatial intensity variations within the captured images and outcomes were used for discriminant analysis. We found that healthy tissues displayed large variations in contrast and correlation features as a function of distance, corresponding to repetitive, increased local intensity fluctuations. Metastatic tissue images exhibited decreased contrast and correlation related values, representing more uniform intensity patterns and smaller fibers, indicating the destruction of the healthy stroma by the cancerous infiltration. The textural outcomes resulted in high classification accuracy as evaluated quantitatively by discriminant analysis.