Response assessment of locally advanced rectal cancer after neoadjuvant chemoradiotherapy: Is apparent diffusion coefficient useful on 3 T magnetic resonance imaging?

AIM: To assess the diagnostic value of apparent diffusion coefficient (ADC) on 3 T device for the prediction of tumoral response to neoadjuvant chemoradiotherapy (nCRT) and for the response assessment after nCRT in patients with locally advanced rectal cancer (LARC), using pathology as a reference. METHODS: Forty-one patients affected by LARC undergoing 3.0 T MRI before and after nCRT were retrospectively selected. After the conventional acquisition of high resolution T2-weighted sequences, diffusion-weighted MRI (DW-MRI) was performed using a spin-echo echo-planar sequence with multiple b values (150, 500, 1000, 1500 s/mm2 ). Fitted ADC values were calculated for each rectal lesion before and after nCRT by drawing a hand-made region of interest (ROI) around the tumour outline. All patients underwent surgery and pathological staging (classified according to tumour regression grading [TRG] and to tumour and node [TN]) represented the reference standard. Pretreatment ADC value (pre-ADC), ADC value obtained after nCRT (post-ADC) and the difference between post-ADC and pre-ADC (ΔADC) were correlated with both the TRG classes and the TN staging system in each patient. RESULTS: The ADC values obtained in the post nCRT examination and the ΔADC were statistically related both to TRG (p = 0.0004; p = 0.0126, respectively) and TN (p = 0.0484; p = 0.0673, respectively) stages at histopathology. On the contrary, the pre-ADC was not related either to the TRG classes or to the lesion TN staging system (p > 0.05). CONCLUSIONS: 3 T DW-MRI using ADC value can be useful to assess the efficacy of nCRT in LARC; in fact, post-ADC and ΔADC values improve MR capability to evaluate tumour response.

Cystic Lesions of the Pancreas: Is Apparent Diffusion Coefficient Value Useful at 3 T Magnetic Resonance Imaging?

OBJECTIVE: The objective of this study is to determine the role of apparent diffusion coefficient (ADC) value at 3T magnetic resonance imaging (MRI) in the characterization of pancreatic cystic lesions. METHODS: We retrospectively selected a total number of 223 patients with a conclusive diagnosis of pancreatic cystic lesion, previously undergoing MR examination on a 3 T system. The MRI protocol first included axial T1/T2-weighted sequences and magnetic resonance cholangiopancreatography. Diffusion-weighted MRI was performed using a spin-echo echo-planar sequence with multiple b values (0, 150, 500, 1000, and 1500 s/mm2) in all diffusion directions, obtaining an ADC map. Contrast-enhanced T1-weighted sequences were performed during the initial work-up of a pancreatic cystic lesion and when signs of malignancy were suspected during the MRI follow-up. The ADC value of each pancreatic lesion was measured using a monoexponential curve fitting with all the multiple b. RESULTS: The final diagnosis of our study group included the following: serous cystadenomas (n = 42), mucinous cystadenomas (n = 14), intraductal papillary mucinous neoplasms (IPMNs) (n = 121), IPMNs with signs of malignancy at histopathologic examination (n = 24), pseudocysts (n = 9), other cystic lesions (n = 13). A statistically significant difference was observed between the ADC values of malignant IPMNs and those of each other group of pancreatic lesions (P < 0.001). The ADC value of benign IPMN was significantly higher than that of serous cystadenomas (P = 0.024). A statistically significant difference was observed between the ADCs of all mucinous cystic tumors (benign IPMNs together to mucinous cystadenomas) and the ADCs of serous cystadenomas (P = 0.014). CONCLUSIONS: Fitted ADC value obtained at 3T MRI may be helpful in the characterization of pancreatic cystic lesions with particular regards of differential diagnosis between mucinous and serous cystic tumors and between malignant and benign IPMNs.

Gadoxetate Disodium-Enhanced MR Cholangiography for Evaluation of Biliary-Enteric Anastomoses: Added Value Beyond Conventional T2-Weighted Images.

OBJECTIVE. The objective of our study was to evaluate image quality and reader confidence in MR cholangiography of bile ducts using conventional T2-weighted MR cholangiography alone in comparison with T2-weighted MR cholangiography and gadoxetate disodium-enhanced MR cholangiography in a series of patients with biliary-enteric anastomosis (BEA). SUBJECTS AND METHODS. Fifty patients with BEA and clinically and sonographically suspected complications underwent 1.5-T MRI. After acquisition of T1- and T2-weighted images, conventional MR cholangiography was performed using 3D fast relaxation fast spin-echo (FRFSE) and single-shot fast spin-echo (SSFSE) T2-weighted sequences (image set 1). In each patient, a 3D fat-suppressed Liver Acquisition with Volume Acceleration (LAVA) sequence was performed before and 15, 20, 25, 30, and 40 minutes after IV administration of 0.1 mL/kg of gadoxetate disodium (Primovist) (image set 2). Two radiologists in consensus evaluated image quality in the anatomic segments of the biliary tract and recorded diagnostic confidence scores for image set 1 alone and image sets 1 and 2 together. MRI findings were compared with postsurgical specimen if surgery was performed, conventional cholangiography, or 12 months of imaging follow-up. RESULTS. A significant improvement in image quality for visualization of all biliary segments was found using gadoxetate disodium-enhanced MR cholangiography in comparison with T2-weighted MR cholangiography alone. Readers judged diagnostic confidence of image set 1 alone and image sets 1 and 2 together as very confident in three and 37 cases, confident in 30 and 11, not confident in 14 and one, and not confident at all in three and 1, respectively. Concordance between image set 1 alone and image sets 1 and 2 together and the reference standard results was present in 23 of 50 cases (46%) and 47 of 50 cases (94%), respectively (p < 0.0001). CONCLUSION. Gadoxetate disodium-enhanced MR cholangiography can improve image quality for visualization of the biliary tract and further enhanced the diagnostic performance of conventional T2-weighted MR cholangiography in the evaluation of patients with BEA.

Incidence and reasons of pancreatic resection in patients with asymptomatic serous cystadenoma.

BACKGROUND/OBJECTIVES: Despite diagnostic refinements, pancreatic resection (PR) is eventually performed in some patients with asymptomatic serous cystadenoma (A-SCA). The aim of this study was to define incidence and reasons of PR in A-SCA. METHODS: A retrospective analysis of a prospectively maintained database was performed for all the patients referred for pancreatic cystic lesions (PCL) between January 2005 and March 2016. RESULTS: Overall, there were 1488 patients with PCL, including 1271 (85.4%) with incidental PCL (I-PCL). During the study period referral of I-PCL increased 8.5-fold. Surgery was immediately advised in 94 I-PCL (7.3%) and became necessary later on in 11 additional patients (0.9%), because of the development of symptoms. Overall, PR was performed in 105/1271 patients presenting with I-PCL (8.2%), including 27 with A-SCA (2.1%). All patients with A-SCA underwent ultrasonography and contrast-enhanced computed tomography. Magnetic resonance imaging was performed in 21 patients (77.8%), 18 F-FDG positron emission tomography in 8 (29.6%), endoscopic ultrasonography (EUS) in 2 (7.4%), and EUS-guided fine needle aspiration (EUS-FNA) in 1 (3.7%). These studies demonstrated a combination of atypical features such as solid tumor (3; 11.1%), oligo-/macrocystic tumor (24; 88.8%), mural nodules (14; 51.8%), enhancing cyst walls (17; 62.9%), dilation of the main pancreatic duct (3; 11.1%), and upstream pancreatic atrophy (1; 3.7%). Additionally, 14/27 patients (51.8%) were females with oligo-/macrocystic tumors located in the body-tail of the pancreas. CONCLUSIONS: Management of patients with A-SCA entails a small risk of PR especially when these tumors demonstrate atypical radiologic features associated with confounding anatomic and demographic characteristics.

Primary sclerosing cholangitis: Is qualitative and quantitative 3 T MR imaging useful for the evaluation of disease severity?

Purpose: To analyze the role of qualitative and quantitative 3 T MR imaging assessment as a non-invasive method for the evaluation of disease severity in patients with primary sclerosing cholangitis (PSC). Methods: A series of 26 patients, with histological diagnosis of PSC undergoing 3 T MRI and hepatological evaluation, was retrospectively enrolled. All MR examinations included diffusion-weighted imaging (DWI), T2-weighted (T2w) and T1-weighted (T1w) sequences, before and after administration of Gd-EOB-DTPA with the acquisition of both dynamic and hepato-biliary phase (HBP). Qualitative analysis was performed by assessment of liver parenchyma and biliary tract changes, also including biliary excretion of gadoxetic acid on HBP. Quantitative evaluation was conducted on liver parenchyma by measurement of apparent diffusion coefficient (ADC) and relative enhancement (RE) on 3-minute delayed phase and on HBP. Results of blood tests (ALT, ALP, GGT, total and direct bilirubin, albumin, and platelets) and transient elastography-derived liver stiffness measurements (TE-LSM) were collected and correlated with qualitative and quantitative MRI findings. Results: Among qualitative and quantitative findings, fibrosis visual assessment and RE had the best performance in estimating disease severity, showing a statistically significant correlation with both biomarkers of cholestasis and TE-LSM. Statistical analysis also revealed a significant correlation of gadoxetic acid biliary excretion with ALT and direct bilirubin, as well as of ADC with total bilirubin. Conclusion: Qualitative and quantitative 3 T MR evaluation is a promising non-invasive method for the assessment of disease severity in patients with PSC.

Biliary-enteric anastomoses: spectrum of findings on Gd-EOB-DTPA-enhanced MR cholangiography.

Biliary-enteric anastomosis is a common surgical procedure performed for the management of a variety of benign and malignant diseases. This procedure presents a high risk of developing complications such as anastomotic leak, hemorrhage, cholangitis, stones, stricture formation, that have been reported as ranging from 3 % to 43 %. Because the endoscopic approach of the biliary tract is generally precluded in this setting, there is clearly a role for a non-invasive imaging technique to follow up these patients and to detect the possible complications. T2-weighted MR cholangiography has been shown to be effective in the evaluation of patients with biliary-enteric anastomosis. Some of these patients may have mild duct dilatation in spite of a patent anastomosis, and stenosis should be considered only when duct dilatation is associated with narrowing of the anastomotic site. T2-weighted MRC depicts the site of biliary-enteric anastomosis, the cause of obstruction, and the status of the biliary ducts upstream. However, the disadvantages of conventional MRC are that it lacks functional information and so, differentiation between obstructive and non-obstructive dilatation of the bile ducts is often extremely difficult. T1-weighted contrast-enhanced MR cholangiography using Gd-EOB-DTPA is a recently emerging technique that is useful for delineating the anatomy of biliary-enteric anastomoses and detecting complications such as strictures, intraductal stones, and biliary leaks; besides, this technique can provide functional information that are extremely promising in the grading of biliary obstruction. We present the spectrum of findings of biliary-enteric anastomoses on Gd-EOB-DTPA-enhanced MR cholangiography focusing on the main clinical applications.

Intraductal oncocytic papillary neoplasm (IOPN): two case reports and review of the literature.

Background: Intraductal oncocytic papillary neoplasms (IOPNs) place at the oncocytic extreme of the intraductal pancreatic neoplasm spectrum and display typical morphological features. Their identification in 1996 by Adsay et al. has been followed by a growing number of cases, paving the way for a deeper understanding of this underestimated entity. Contrarily to intraductal papillary mucinous neoplasms (IPMNs), most IOPNs run an indolent course and surgery is usually curative. Pancreatic IOPNs tend to develop from the main pancreatic duct (MPD) and their diagnosis is either incidental or subsequent to mass-related symptoms. Up to 30% of cases show concomitant areas of minimal stromal invasion and loco-regional or systemic spread are confined to a minority of cases. Biological hallmarks of IOPNs are being identified, including recurrent kinase gene rearrangements. Morphological and biological traits of IOPNs seem to overlap with those of other malignancies. A deeper understanding of these entities is needed in order to shed light upon the nature of pancreato-biliary oncocytic neoplasms. This case report describes two patients with a diagnosis of IOPN-one of them accounting for the largest IOPN ever described-and provides a brief review of recent discoveries on the subject. Case Description: We describe two cases of IOPN occurring in adult male patients, respectively in their 60s and 70s. Both patients had unremarkable clinical history. In case 1 the diagnosis was coincidental to a right renal colic; case 2 complained a right lumbar pain radiating to the homolateral groin. In both cases imaging analyses revealed a voluminous pancreatic mass, posing the indication to laparoscopic pancreatectomy. Gross and histological features were consistent with the diagnosis of IOPN. Surgical margin were free from disease and the patient did not undergo further treatment. After a 10- and 7-month follow-up respectively, patients did not experience relapse. Conclusions: Recent immunohistochemical (IHC) and molecular data reveal unique characteristics of IOPNs, highlighting the substantial differences from IPMNs. Further research is needed in order to identify novel prognostic and predictive markers applicable to oncocytic neoplasms of the pancreato-biliary tract.

Diagnostic and Therapeutic Radiology of the GI Tract, Liver, and Pancreas in Patients with COVID.

Coronavirus disease 2019 (COVID-19) pulmonary involvement has been extensively reported in the literature. Current data highlight how COVID-19 is a systemic disease, affecting many other organs, including the gastrointestinal, hepatobiliary, and pancreatic organs. Recently, these organs have been investigated using imaging modalities of ultrasound and particularly computed tomography. Radiological findings of the gastrointestinal, hepatic, and pancreatic involvement in patients with COVID-19 are generally nonspecific but are nonetheless helpful to evaluate and manage COVID-19 patients with involvement of these organs.

Exploring the Outcome of Disappearance or Small Remnants of Colorectal Liver Metastases during First-Line Chemotherapy on Hepatobiliary Contrast-Enhanced and Diffusion-Weighted MR Imaging.

We aimed to evaluate the outcome of the disappearance or small remnants of colorectal liver metastases during first-line chemotherapy assessed by hepatobiliary contrast-enhanced and diffusion-weighted MR imaging (DW-MRI). Consecutive patients with at least one disappearing liver metastasis (DLM) or small residual liver metastases (≤10 mm) assessed by hepatobiliary contrast-enhanced and DW-MRI during first-line chemotherapy were included. Liver lesions were categorized into three groups: DLM; residual tiny liver metastases (RTLM) when ≤5 mm; small residual liver metastases (SRLM) when >5mm and ≤10 mm. The outcome of resected liver metastases was assessed in terms of pathological response, whereas lesions left in situ were evaluated in terms of local relapse or progression. Fifty-two outpatients with 265 liver lesions were radiologically reviewed; 185 metastases fulfilled the inclusion criteria: 40 DLM, 82 RTLM and 60 SRLM. We observed a pCR rate of 75% (3/4) in resected DLM and 33% (12/36) of local relapse for DLM left in situ. We observed a risk of relapse of 29% and 57% for RTLM and SRLM left in situ, respectively, and a pCR rate of about 40% overall for resected lesions. DLM assessed via hepatobiliary contrast-enhanced and DW-MRI very probably indicates a complete response. The surgical removal of small remnants of liver metastases should always be advocated whenever technically possible.

Vessel-Guided Mesohepatectomy for Liver Partition and Staged Major Parenchyma-Sparing Hepatectomies with Super-Selective Portal Vein Embolization or Enhanced ALPPS to Achieve R0 Resection for Colorectal Liver Metastases at the Hepatocaval Confluence.

Background. R0 minor parenchyma-sparing hepatectomy (PSH) is feasible for colorectal liver metastases (CRLM) in contact with hepatic veins (HV) at hepatocaval confluence since HV can be reconstructed, but in the case of contact with the first-order glissonean pedicle (GP), major hepatectomy is mandatory. To pursue an R0 parenchyma-sparing policy, we proposed vessel-guided mesohepatectomy for liver partition (MLP) and eventually combination with liver augmentation techniques for staged major PSH. Methods. We analyzed 15 consecutive vessel-guided MLPs for CRLM at the hepatocaval confluence. Patients had a median of 11 (range: 0-67) lesions with a median diameter of 3.5 cm (range: 0.0-8.0), bilateral in 73% of cases. Results. Grade IIIb or more complications occurred in 13%, median hospital stay was 14 (range: 6-62) days, 90-day mortality was 0%. After a median follow-up of 17.5 months, 1-year OS and RFS were 92% and 62%. In nine (64%) patients, MLP was combined with portal vein embolization (PVE) or ALPPS to perform staged R0 major PSH. Future liver remnant (FLR) volume increased from a median of 15% (range: 7-20%) up to 41% (range: 37-69%). Super-selective PVE was performed in three (33%) patients and enhanced ALPPS (e-ALPPS) in six (66%). In two e-ALPPS an intermediate stage of deportalized liver PSH was necessary to achieve adequate FLR volume. Conclusions. Vessel-guided MLP may transform the liver in a paired organ. In selected cases of multiple bilobar CRLM, to guarantee oncological radicality (R0), major PSH is feasible combining advanced surgical parenchyma sparing with liver augmentation techniques when FLR volume is insufficient.

Pictorial review: radiological diagnosis of anastomotic leakage with water-soluble contrast enema after anterior resection of the rectum.

For patients who have undergone colorectal surgery, anastomotic leakage is a serious and challenging complication with a variable rate ranging between 1.8% and 19.2%. Postoperative anastomotic leaks after colorectal surgery can have severe consequences for patients, particularly ones who present with few or no symptoms. Computed tomography and/or water-soluble contrast enema (WSE) are the most frequently utilized imaging methods to identify and diagnose anastomotic leaks early. WSE is a safe and complication-free procedure that allows to identify the presence of otherwise unrecognized anastomotic leaks, both in asymptomatic and symptomatic patients. Fluoroscopic rectal examination using a water-soluble contrast agent for postoperative patients is never an easy examination to perform since it requires careful preparation, skill, and knowledge. Four morphological types of anastomotic dispersion have been described: "saccular type", "horny type", "serpentine type" and "dendritic type". Among 4 types of leakage, dendritic and serpentine types are more frequently followed by clinical symptoms and none of the dendritic type resolves spontaneously. On the other hand, the saccular and horny types have a better prognosis after healing of the loss and subsequent restoration of the ostomy as they consist of a cavity that provides a sort of physical barrier to the spread of inflammation. The aim of this pictorial essay was to illustrate the spectrum of imaging findings of morphological types of radiologic leakages on WCE in patients with colorectal surgical anastomosis. We have also tried to provide tips and tools to enable identification of radiological leakages on retrograde WCE, particularly of the smallest leaks which can be more easily missed.

Chemotherapy-Induced Liver Injury in Patients with Colorectal Liver Metastases: Findings from MR Imaging.

Chemotherapy-induced liver injury has been found to be quite common in cancer patients undergoing chemotherapy. Being aware of chemotherapy-induced hepatotoxicity is important for avoiding errors in detecting liver metastases and for defining the most appropriate clinical management strategy. MRI imaging has proven to be a useful troubleshooting tool that helps overcome false negatives in tumor response imaging after chemotherapy due to liver parenchyma changes. The purpose of this review is, therefore, to describe the characteristics of magnetic resonance imaging of the broad spectrum of liver damage induced by systemic chemotherapeutic agents in order to avoid misdiagnoses of liver metastases and disease progression and to define the most appropriate clinical management strategy.

Impact of baseline gadoxetic acid-enhanced liver magnetic resonance and diffusion-weighted imaging in resectable colorectal liver metastases: A prospective, monocentric study.

BACKGROUND: Liver magnetic resonance imaging (MRI) utilizing hepatocyte-specific contrast agent and diffusion-weighted imaging (DWI) is currently used to properly stage colorectal liver metastases (CRLM) in patients candidate to liver surgery. However, the added value of liver MRI in choosing the treatment strategy in resectable CRLM over computed tomography (CT)-scan is not clear. PATIENTS AND METHODS: This is a prospective monocentric collection of consecutive cases of patients with CRLM conceived with the aim to assess the added value of liver MRI in changing the initial treatment strategy planned according to CT-scan. Potential changes in the initially planned strategy were defined as: - from upfront surgery to perioperative chemotherapy (fluoropyrimidine and oxaliplatin) - from upfront surgery to first-line systemic therapy (doublet or triplet plus a biological agent) - from perioperative chemotherapy to first-line systemic therapy. Hypothesising that MRI may induce a change in the choice of the treatment strategy in the 20% of cases (alternative hypothesis), against a null hypothesis of 5%, with one-tailed alpha and beta errors of 0.05 and 0.20 respectively, 27 patients were needed. The added value of liver MRI would have been considered clinically meaningful if at least 4 changes in the treatment strategy were observed. RESULTS: Among 27 enrolled patients, upfront surgery and perioperative chemotherapy strategies were chosen in 17 (63%) and 10 (37%) cases, respectively, based on CT-scan. After liver MRI, additional liver lesions were found in 8 patients (30%) and the initial strategy was changed in 7 patients (26%) (4 initially deemed candidate to upfront surgery and 3 initially sent to perioperative chemotherapy) that were treated with first-line systemic therapy. CONCLUSIONS: Our results support the indication of the current guidelines on the routine use of liver MRI in the initial workup of patients with resectable CRLM with an MRI-driven changes of initial treatment plan in a relevant percentage of cases.

MR imaging features of multiple biliary hamartomas (Von Meyenburg Complex): A pictorial review and differential diagnosis.

Biliary hamartomas (BHs) are rare malformative cystic/cystic-like lesions of the liver affecting the biliary tree, named after Hanns von Meyenburg who described them for the first time and still known with this eponym to this day. They usually lack clinical symptoms, and abnormalities in liver function tests are unusual; thus, it is typically an incidental finding of liver imaging. Despite being benign lesions, BHs can pose clinical challenges; the first one is differential diagnosis with other more relevant pathological conditions. Therefore, knowledge of MR imaging findings of BHs is helpful for a prompt and correct diagnosis, avoiding unnecessary invasive procedures and/or an excessive number of radiological investigations. This pictorial review is aimed to depict the most typical MR imaging features of multiple biliary hamartomas (von Meyenburg Complex), in order to familiarize the diagnosis and facilitate the differentiation from other hepato-biliary cystic diseases.

Diffusion-weighted MRI of solid pancreatic lesions: Comparison between reduced field-of-view and large field-of-view sequences.

PURPOSE: To compare the image quality, presence of artifacts and apparent diffusion coefficient (ADC) values of reduced field-of-view (rFOV) and large FOV (lFOV) single-shot spin-echo echo-planar diffusion-weighted imaging (DWI) in the evaluation of solid pancreatic lesion. METHOD: The 3T MR examinations of 60 patients with solid pancreatic lesions were examined. Two Readers independently performed qualitative analysis and quantitative measurements of the ADC values of the solid pancreatic lesions in both rFOV and lFOV DWI sequence. The qualitative analysis parameters included: 1) Sharpness, 2) Distortion, Ghosting, Motion and Susceptibility artifacts, 3) Lesion Conspicuity and 4) Overall Image Quality. These parameters were evaluated using a 4-point scale. The T-test for paired data was used to compare qualitative scores and the ADC values of the rFOV and lFOV DWI sequences, and to assess inter-reader agreement. RESULTS: The qualitative analysis yielded scores for the rFOV DWI sequence, which were better for sharpness, artifacts, and overall image quality as compared to the lFOV DWI sequence according to the only Reader 2 (the most experienced) (p ≤ 0.001). As to lesion conspicuity, no significant difference was found by either Reader (p ≥ 0.245). As to quantitative analysis, both Readers found no significant difference between the two sequences in the ADC values of various solid pancreatic lesions (p ≥ 0.156). CONCLUSIONS: The rFOV DWI sequence of the pancreas provides better anatomic structure visualization, reduced artifacts, and better overall image quality as compared to the lFOV DWI sequence according to the Reader with the more experience in abdominal MRI. The ADC values were not significantly different in the two sequences. The rFOV DWI sequence could be included in the standard MRI protocol for the pancreas.

Abdominal and gastrointestinal manifestations in COVID-19 patients: Is imaging useful?

Coronavirus disease 2019 (COVID-19) can be considered a systemic disease with a specific tropism for the vascular system, in which the alterations of the microcirculation have an important pathogenetic role. The lungs are the main organ involved in COVID-19, and severe progressive respiratory failure is the leading cause of death in the affected patients; however, many other organs can be involved with variable clinical manifestations. Concerning abdominal manifestations, the gastrointestinal tract and the hepatobiliary system are mainly affected, although the pancreas, urinary tract and spleen may also be involved. The most common gastrointestinal symptoms are loss of appetite, followed by nausea and vomiting, diarrhea and abdominal pain. Gastrointestinal imaging findings include bowel wall thickening, sometimes associated with hyperemia and mesenteric thickening, fluid-filled segments of the large bowel and rarely intestinal pneumatosis and ischemia. Hepatic involvement manifests as an increase in the enzymatic levels of alanine aminotransferase, aspartate aminotransferase, serum bilirubin and γ-glutamyl transferase with clinical manifestations in most cases mild and transient. The most frequent radiological features are hepatic steatosis, biliary sludge and gallstones. Edematous acute pancreatitis, kidney infarct and acute kidney injury from acute tubular necrosis have been described more rarely in COVID-19. Lastly, splenic involvement is characterized by splenomegaly and by the development of solitary or multifocal splenic infarcts with classic wedge-shaped or even rounded morphology, with irregular or smooth profiles. In summary, the abdominal radiological findings of COVID-19 are nonspecific and with poor pathological correlation reported in the literature. Ultrasound and particularly computed tomography with multiphasic acquisition are the diagnostic methods mainly utilized in COVID-19 patients with abdominal clinical symptoms and signs. Although radiological signs are not specific of abdominal and gastrointestinal involvement, the diagnostic imaging modalities and in particular computed tomography are helpful for the clinician in the management, evaluation of the severity and evolution of the COVID-19 patients.

Colorectal liver metastases: ADC as an imaging biomarker of tumor behavior and therapeutic response.

PURPOSE: To correlate the ADC values of colorectal liver metastases, evaluated before (preADC) and after (postADC) neoadjuvant chemotherapy (ChT), as well as their difference (ΔADC), with the histological tumor regression grade (TRG) and to determine whether the preADC value can be predictive of the lesion ChT response. METHOD: Twenty-four patients with colorectal liver metastases, who had undergone 3 T-MRI before and after ChT and were subsequently treated by parenchymal-spearing surgery, were retrospectively included. Diffusion-weighted MRI (DW-MRI) was performed using a spin-echo echo-planar sequence with multiple b values, obtaining an ADC map. Fitted ADC values were calculated for each lesion before and after ChT. The maximum diameter of each lesion in both examinations was recorded. Diameter variations and RECIST1.1 criteria were assessed. All MRI findings were histopathologically correlated to TRG of resected liver metastases. Statistical analysis was performed on a per-lesion basis. RESULTS: A total of 58 colorectal liver metastases were analysed; after ChT, 8 out of 58 lesions disappeared. TRG1, TRG2, TRG3, TRG4 and TRG5 were observed in 6, 12, 12, 13 and 7 lesions, respectively. The preADC values showed a different distribution according to the TRG scores (p = 0.0027), even though the distribution was not linear. The postADC and ΔADC values were significant different based on the TRG system (both p < 0.0001). A significant correlation between the lesion TRG and the evaluation according to RECIST1.1 criteria was observed by a per-lesion analysis (p = 0.0009). CONCLUSIONS: PostADC and ΔADC could be proposed as reliable biomarkers to assess tumor treatment response after preoperative ChT in patients with colorectal liver metastases.

MR cholangiography in orthotopic liver transplantation: sensitivity and specificity in detecting biliary complications.

BACKGROUND: To assess the diagnostic value of magnetic resonance cholangiography (MRC) when evaluating biliary complications in a large series of liver transplants. METHODS: One hundred and twenty-nine patients prospectively underwent magnetic resonance (MR) imaging and MR cholangiography at 1.5-T device after orthotopic liver transplantation (OLT). After the preliminary acquisition of axial T1- and T2-weighted images, MRC involved respiratory-triggered, thin-slab (2 mm), heavily T2-weighted fast spin-echo and breath-hold, thick-slab (10-50 mm), single-shot T2-weighted sequences. MR images were blindly evaluated by two experienced readers in conference to determine the biliary anatomy and the presence of complications, whose final diagnosis was based on endoscopic retrograde cholangiography, percutaneous trans-hepatic cholangiography, and by integrating clinical follow-up with ultrasound and/or MR findings. RESULTS: Biliary complications were found in 60 patients (46.5%) and were represented by ischemic-type biliary lesions (n=21); anastomotic strictures (n=13); non-anastomotic strictures (n=5); anastomotic strictures associated to lithiasis (n=6); lithiasis (n=6); papillary dysfunctions (n=9). The sensitivity, specificity, positive predictive value, and negative predictive value of the reviewers for the detection of all types of biliary complications in patients with OLT were 98%, 94%, 94%, and 98%, respectively. CONCLUSIONS: MRC is a reliable technique for detecting post-OLT biliary complications and should be recommended before planning therapeutic interventions.

A Splenic IgG4+ Sclerosing Angiomatoid Nodular Transformation (SANT) Treated by Hemisplenectomy: A Radiologic, Histochemical, and Immunohistochemical Study.

INTRODUCTION: Sclerosing angiomatoid nodular transformation (SANT) is a rare benign lesion of unknown origin for which total splenectomy is the standard treatment. CASE PRESENTATION: A 54-year-old man with a history of recurrent pancreatitis, bicuspid aortic valve, and aortic dissection underwent abdominal ultrasound, Computed tomography and magnetic resonance imaging, which revealed a 6-cm hypoechoic splenic mass diagnosed as cavernous hemangioma. Owing to his relevant past history, he was considered eligible for emisplenectomy and not for total excision, which is associated with long-term risks, especially infections. RESULTS: Histologic examination revealed several nodules of varying size separated by sclerotic stroma with scattered inflammatory cells rich in IgG4+ in a background of splenic red pulp. Immunohistochemical stains showed a characteristic panel for CD34, CD31, and CD8. CONCLUSIONS: The diagnosis of SANT should be considered in any patient presenting with a splenic lesion containing an angiomatoid or inflammatory component. The only method able to establish a correct diagnosis is histologic and immunohistochemical evaluation. Complete splenectomy is generally considered the best approach. However, if the patient is at high risk of infection and localization of the lesion allows for selective devascularization of the affected part of the spleen, the lesion could be removed by hemisplenectomy. In some patients SANT is related to high blood levels of IgG4. Thus, corticosteroids might be useful for treating IgG4+ SANT and for preventing other IgG4-related diseases.

Side-branch intraductal papillary mucinous neoplasms of the pancreas: outcome of MR imaging surveillance over a 10 years follow-up.

PURPOSE: To evaluate the outcome of a MR imaging procotol in assessing the evolution of individuals with branch duct - intraductal papillary mucinous neoplasms (BD-IPMN) without worrisome features (WF) and/or high risk stigmata (HRS) at the time of the diagnosis in a follow-up period of at least 10 years. MATERIAL AND METHODS: A retrospective revision of a prospectively collected radiological database including a total number of 600 patients who were investigated and diagnosed with "presumed" diagnosis of BD-IPMN at MRI/MRCP at our Department since 2008 was performed. Inclusion criteria were: 1) absence of worrisome features and/or high-risk stigmata at the time of diagnosis (baseline); 2) a radiological follow-up with abdominal MRI/MRCP of at least 10 years. Changes in cysts size, development of WF, HRS and pancreatic cancer, and any other modification during the follow-up were retrospectively analysed by two observers in consensus. RESULTS: Sixty-nine patients fulfilled all the inclusion criteria. During surveillance, the cysts remained dimensionally unchanged or slightly reduced in size in 26.2% and 4.3% of cases respectively, whereas cyst enlargement was demonstrated in 69.5% of cases. Median annual growth rate was of 0.97 ± 0.87 mm/yr (range 0.13-5.0). WF and HRS developed in 10/69 (14.5%) and 3/69 (4.3%) cases, respectively. The incidence of pancreatic cancer in patients with BD-IPMN was 2.9%. CONCLUSION: Our data confirm the low risk of pancreatic cancer development in patients with BD-IPMN, thus justifying an imaging follow-up. Worrisome features and high-risk stigmata were promptly identified during the follow-up, supporting the utility of our surveillance MR imaging protocol.