Pancreatic cysts: can surveillance interval for small low-risk lesions be lengthened?

BACKGROUND: Surveillance of pancreatic cysts are necessary due to risk of malignant transformation. However, reported progression rates to advanced neoplasia are variable and the high frequency of surveillance scans may pose a considerable burden on healthcare resources. PURPOSE: To validate the effectiveness of the Fukuoka Guidelines surveillance regime and determine if a longer surveillance interval can be established. MATERIAL AND METHODS: All magnetic resonance imaging (MRI) studies of the pancreas performed at our institution between January 2014 and December 2016 with at least one pancreatic cystic lesion and follow-up MRI or computed tomography (CT) over at least two years were reviewed for size, worrisome feature (WF), and high-risk stigmata (HRS) at diagnosis and follow-up imaging (up to year 6). Reference standards for advanced neoplasia were based on endoscopic ultrasound, fine needle aspiration cytology, or the presence of ≥2 WF or ≥1 HRS on imaging. Comparison of MRI features of progression and outcomes of diagnostic endpoints between lesions <20 mm and ≥20 mm was performed. RESULTS: A total of 270 patients were included (201 cysts <20 mm, 69 cysts ≥20 mm). Compared with cysts <20 mm, cysts ≥20 mm were more likely to be associated with WF or HRS (40.6% vs. 12.4%; P ≤0.00001), demonstrate increase in size of ≥5 mm in two years (20.3% vs. 10.9%; P = 0.049), and develop advanced neoplasia (24.6% vs. 0.5%; P <0.00001). CONCLUSION: Pancreatic cysts <20 mm have a low risk of developing WF and HRS and surveillance interval may be lengthened.

Is the extent of functional liver remnant increase truly "functional"? A single-institution case series of patients with Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS).

Aim of the study: Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS) aims to induce rapid hypertrophy of the future liver remnant (FLR) to reduce the risk of post-hepatectomy liver failure (PHLF). However, volumetric increase does not correspond to functional increase. This is a novel study which aims to compare the increase in standardized FLR (sFLR) vs. indocyanine green retention at 15 minutes (ICG-R15). Material and methods: This is a retrospective case series of patients who underwent ALPPS between May 2015 and January 2022. Primary outcomes were sFLR and ICG-R15. Secondary outcomes were incidence of PHLF, morbidity, recurrence, overall survival (OS) and disease-free survival (DFS). Results: There were 10 patients with median age of 60.5 years (range 29-69). Most patients had adenocarcinoma secondary to colorectal origin (80%). There were 7 patients who received neoadjuvant chemotherapy [median 6 cycles (range 5-9)]. Median size of the primary tumour was 5.0 cm (range 2.0-7.0 cm). There was a significant increase in median ICG-R15 after stage 1 ALPPS (8.8% vs. 10.2%, p = 0.024) and increase in median sFLR after stage 1 ALPPS (34.4% vs. 53.0%, p = 0.012). Linear regression showed no significant correlation between sFLR increase and ICG-R15 (B = 0.26, 95% CI: -0.82, 1.34, p = 0.565). One patient had PHLF. Median time to local recurrence and metastatic recurrence was 14.4 months (range 6.9-21.9) and 7.5 months (range 6.9-17.3) respectively. OS and DFS were 50% and 40% respectively. Conclusions: No significant relationship was observed between ICG-R15 and sFLR. Volume increase may overestimate the functional increase following ALPPS. Larger studies are needed to validate our findings.

Efficacy of texture analysis of pre-operative magnetic resonance imaging in predicting microvascular invasion in hepatocellular carcinoma.

BACKGROUND: Presence of microvascular invasion (MVI) indicates poorer prognosis post-curative resection of hepatocellular carcinoma (HCC), with an increased chance of tumour recurrence. By present standards, MVI can only be diagnosed post-operatively on histopathology. Texture analysis potentially allows identification of patients who are considered 'high risk' through analysis of pre-operative magnetic resonance imaging (MRI) studies. This will allow for better patient selection, improved individualised therapy (such as extended surgical margins or adjuvant therapy) and pre-operative prognostication. AIM: This study aims to evaluate the accuracy of texture analysis on pre-operative MRI in predicting MVI in HCC. METHODS: Retrospective review of patients with new cases of HCC who underwent hepatectomy between 2007 and 2015 was performed. Exclusion criteria: No pre-operative MRI, significant movement artefacts, loss-to-follow-up, ruptured HCCs, previous hepatectomy and adjuvant therapy. Fifty patients were divided into MVI (n = 15) and non-MVI (n = 35) groups based on tumour histology. Selected images of the tumour on post-contrast-enhanced T1-weighted MRI were analysed. Both qualitative (performed by radiologists) and quantitative data (performed by software) were obtained. Radiomics texture parameters were extracted based on the largest cross-sectional area of each tumor and analysed using MaZda software. Five separate methods were performed. Methods 1, 2 and 3 exclusively made use of features derived from arterial, portovenous and equilibrium phases respectively. Methods 4 and 5 made use of the comparatively significant features to attain optimal performance. RESULTS: Method 5 achieved the highest accuracy of 87.8% with sensitivity of 73% and specificity of 94%. CONCLUSION: Texture analysis of tumours on pre-operative MRI can predict presence of MVI in HCC with accuracies of up to 87.8% and can potentially impact clinical management.

Algorithm-based approach to focal liver lesions in contrast-enhanced ultrasound.

Focal liver lesions are commonly encountered. Grey-scale and Doppler sonographic characteristics of focal liver lesions are often non-specific and insufficient to conclusively characterise lesions as benign or malignant. Contrast-enhanced ultrasound is useful for the characterisation of FLLs in patients who are unable to undergo contrast-enhanced computed tomography or magnetic resonance imaging. It is also easily available and relatively cheap. However, interpretation of contrast-enhanced ultrasound can be challenging without a systematic approach. In this pictorial essay, we highlight an algorithm-based approach to FLLs and discuss the characteristic contrast-enhanced ultrasound features of commonly encountered and clinically significant focal liver lesions.

Variant Hepatocellular Carcinoma Subtypes According to the 2019 WHO Classification: An Imaging-Focused Review.

The 2019 5th edition of the WHO classification of digestive system tumors estimates that up to 35% of hepatocellular carcinomas (HCCs) can be classified as one of eight subtypes defined by molecular characteristics: steatohepatitic, clear cell, macrotrabecular-massive, scirrhous, chromophobe, fibrolamellar, neutrophil-rich, and lymphocyte-rich HCCs. Due to their distinct cellular and architectural characteristics, these subtypes may not display arterial phase hyperenhancement and washout appearance, which are the classic MRI features of HCC, creating challenges in noninvasively diagnosing such lesions as HCC. Moreover, certain subtypes with atypical imaging features have a worse prognosis than other HCCs. A range of distinguishing imaging features may help raise suspicion that a liver lesion represents one of these HCC subtypes. In this review, we describe the MRI features that have been reported in association with various HCC subtypes according to the 2019 WHO classification, with attention given to the current understanding of these subtypes' pathologic and molecular bases and relevance to clinical practice. Imaging findings that differentiate the subtypes from benign liver lesions and non-HCC malignancies are highlighted. Familiarity with these sub-types and their imaging features may allow the radiologist to suggest their presence, though histologic analysis remains needed to establish the diagnosis.

Imaging patterns in non-traumatic spleen lesions in adults-a review.

The spleen is a complex organ involved in multiple physiological processes in the human body. Elective splenectomy is an uncommon operation, and the precise characterization of the lesion should be achieved to determine the risks and benefits of this operation accurately. Given the significant role of the spleen in homeostasis and the potential risks of the surgery itself and following sequelae such as infection susceptibility, accurate recognition, and classification of splenic lesions is required before surgery. This review provides an overview of malignant (e.g., lymphoma, angiosarcoma) and benign (e.g., cysts, hemangioma, hamartoma) splenic lesions that may warrant an elective splenectomy. Images from a cohort of adult patients undergoing isolated splenectomy for non-traumatic indications in a single center are provided. This review highlights the considerable overlap in imaging patterns between splenic lesions, splenic lesions masquerading as lesions in other organs, increased detection of asymptomatic splenic incidentalomas due to improvements in imaging modalities. This review also provides clinical correlations for each lesion, providing additional information to help clinicians differentiate between lesions and accurately identify diseases amenable to surgical management.

Imaging mimickers of cholangiocarcinoma: a pictorial review.

Cholangiocarcinoma (CCA) is the second most common primary hepatobiliary malignancy and presents as three separate morphological subtypes; namely mass-forming, periductal-infiltrating, and intraductal-growing patterns. Each of these subtypes have distinct imaging characteristics, as well as a variety of benign and malignant mimics, making accurate diagnosis of CCA on imaging challenging. Whilst histopathological examination is required to arrive at a definitive diagnosis, it is still important for radiologists to be cognizant of these entities and provide reasonable differential diagnoses, as these potentially have a large impact on patient management. This pictorial essay illustrates the three morphological subtypes of CCA, as well as some important mimics for each subtype, that are encountered in clinical practice.

Association between Visceral Adipose Tissue and Non-Alcoholic Steatohepatitis Histology in Patients with Known or Suspected Non-Alcoholic Fatty Liver Disease.

(1) Purpose: To determine the association between visceral adipose tissue (VAT) and proton density fat fraction (PDFF) with magnetic resonance imaging (MRI), and hepatic steatosis (HS), non-alcoholic steatohepatitis (NASH) and hepatic fibrosis (HF) in patients with known or suspected non-alcoholic fatty liver disease (NAFLD). (2) Methods: 135 subjects that had a liver biopsy performed within 3 months (bariatric cohort) or 1 month (NAFLD cohort) of an MRI exam formed the study group. VAT volume was quantified at L2-L3 level on opposed-phase images with signal intensity-based painting using a semi-quantitative software. Liver PDFF and pancreas PDFF were calculated on fat fraction maps. Liver volume (Lvol) and spleen volume (Svol) were also calculated using a semi-automated 3D volume tool available on PACS. A histological analysis was performed by an expert hepatopathologist blinded to imaging findings. (3) Results: The mean Lvol, Svol, liver PDFF, pancreas PDFF and VAT of the study population were 2492.2 mL, 381.6 mL, 13.2%, 12.7% and 120.6 mL, respectively. VAT showed moderate correlation with liver PDFF (r = 0.41, p < 0.001) and weak correlation with Lvol (r = 0.38, p < 0.001), Svol (r = 0.20, p = 0.025) and pancreas PDFF (rs = 0.29, p = 0.001). VAT, Lvol and liver PDFF were significantly higher in patients with HS (p < 0.001), NASH (p < 0.05) and HF (p < 0.05). VAT was also significantly higher in the presence of lobular inflammation (p = 0.019) and hepatocyte ballooning (p = 0.001). The cut-off VAT volumes for predicting HS, NASH and HF were 101.8 mL (AUC, 0.7), 111.8 mL (AUC, 0.64) and 111.6 mL (AUC, 0.66), respectively. (4) Conclusion: The MRI determined VAT can be used for predicting the presence of HS, NASH and HF in patients with known or suspected NAFLD.

Benign focal liver lesions masquerading as primary liver cancers on MRI.

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the most common primary liver malignancies. HCC and ICC have characteristic imaging findings, but a number of benign entities can appear similar and can cause diagnostic dilemma. Ideally, accurate and timely diagnosis of these conditions can help the patient to avoid a needle biopsy or even unnecessary treatment. In this article, we present various benign liver lesions that display imaging characteristics that are similar to HCC and ICC on magnetic resonance imaging (MRI) and discuss salient features that may assist in accurate diagnosis.

Comparison of liver stiffness measurement with MRE and liver and spleen volumetry for prediction of disease severity and hepatic decompensation in patients with primary sclerosing cholangitis.

PURPOSE: To compare liver stiffness measurement (LSM) with magnetic resonance elastography (MRE) and liver and spleen volumetry for prediction of disease severity and hepatic decompensation in primary sclerosing cholangitis (PSC). METHODS: This retrospective study was approved by the institutional review board. Magnetic resonance imaging (MRI) and MRE studies were reviewed, and mean LSM of entire liver, right lobe and left lobe, total liver, right lobe, left lobe, caudate lobe, and spleen volumes were calculated. Qualitative evaluation of lobar atrophy or hypertrophy and presence of macronodular regeneration (MNR) was recorded. Statistical analysis was performed to evaluate correlations between LSM, volumetry measurements, and Mayo risk score. Univariate and multivariate analyses were performed to predict hepatic decompensation. RESULTS: A total of 266 patients with PSC were included in the study. Lobar stiffness measures were higher in the presence of relative lobe atrophy. Mean LSM was higher in the presence of MNR. Significant correlations were observed between mean LSM and volumetry measurements with a fair correlation between LSM and spleen volume (rs = 0.526, p < 0.0001). Among the measurements, the best correlation was observed between mean LSM and Mayo risk score (rs = 0.646, p < 0.0001). In the multivariate analyses, mean LSM and Mayo risk score were significantly associated with liver decompensation (hazard ratio, 1.18; 95%CI 1.02-1.36 and hazard ratio, 1.65; 95%CI 1.08-2.53, respectively). CONCLUSION: LSM with MRE performs significantly better than liver and spleen volumes for prediction of both disease severity and hepatic decompensation.

Clinics in diagnostic imaging (198). Small bowel obstruction secondary to a bezoar.

A 60-year-old man presented with abdominal pain. He was later diagnosed on imaging to have high-grade small bowel obstruction. The patient underwent surgery, and a hard, rounded bezoar resembling the endosperm of Nypa fruticans, colloquially known as attap chee, was found at the point of obstruction. Small bowel obstruction is a common acute surgical condition with multiple causes, including bezoars. We discuss the typical imaging features of bezoars causing small bowel obstruction as well as potential pitfalls that can mimic the appearance of a bezoar.

Pathological variants of hepatocellular carcinoma on MRI: emphasis on histopathologic correlation.

Hepatocellular carcinoma (HCC) is a unique tumor because it is one of the few cancers which can be treated based on imaging alone. Magnetic resonance imaging (MRI) carries higher sensitivity and specificity for the diagnosis of HCC than either computed tomography (CT) or ultrasound. MRI is imaging modality of choice for the evaluation of complex liver lesions and HCC because of its inherent ability to depict cellularity, fat, and hepatocyte composition with high soft tissue contrast. The imaging features of progressed HCC are well described. However, many HCC tumors do not demonstrate classical imaging features, posing a diagnostic dilemma to radiologists. Some of these can be attributed to variations in tumor biology and histology, which result in radiological features that differ from the typical progressed HCC. This pictorial review seeks to demonstrate the appearance of different variants of HCC on MRI imaging, in relation to their histopathologic features.

Clinics in diagnostic imaging (172). Colocolic intussusception with a lipoma as the lead point.

A 50-year-old Chinese man presented with abdominal pain associated with bloody mucoid stools, loss of appetite and weight loss. Contrast-enhanced computed tomography of the abdomen and pelvis revealed a colocolic intussusception secondary to a lipoma. The patient subsequently underwent a left hemicolectomy. Clinical and imaging findings of intussusception in adults are discussed in this article.