Pancreatic cancer outcome-local treatment with radiation using MRI-LINAC.

Introduction: Stereotactic MR-guided on-table adaptive radiotherapy (SMART) allows the precise delivery of high-dose radiation to tumors in great proximity to radiation-sensitive organs. The aim of this study is to evaluate the toxicity and clinical outcome in locally advanced or recurrent pancreatic tumors, with or without prior irradiation, treated with SMART. Methods: Patients were treated for pancreatic cancer (PC) using SMART technology to a prescribed dose of 50 Gy (BED10, 100 Gy) in five fractions, with daily on-table adaptation of treatment plan. Endpoints were acute and late toxicities, local control, local disease-free period, and overall survival. Results: A total of 54 PC patients were treated between August 2019 and September 2022, with a median follow-up of 8.9 months from SMART. The median age was 70.4 (45.2-86.9) years. A total of 40 patients had upfront inoperable PC (55% were locally advanced and 45% metastatic), and 14 had local recurrence following prior pancreatectomy (six patients also had prior adjuvant RT). Of the patients, 87% received at least one chemotherapy regimen (Oxaliplatin based, 72.2%), and 25.9% received ≥2 regimens. Except from lower CA 19-9 serum level at the time of diagnosis and 6 weeks prior to SMART in previously operated patients, there were no significant differences in baseline parameters between prior pancreatectomy and the inoperable group. On-table adaptive replanning was performed for 100% of the fractions. No patient reported grade ≥2 acute GI toxicity. All previously irradiated patients reported only low-grade toxicities during RT. A total of 48 patients (88.9%) were available for evaluation. Complete local control was achieved in 21.7% (10 patients) for a median of 9 months (2.8-28.8); three had later local progression. Eight patients had regional or marginal recurrence. Six- and 12-month OS were 75.0% and 52.1%, respectively. Apart from mild diarrhea 1-3 months after SMART and general fatigue, there were no significant differences in toxicity and outcomes between post-pancreatectomy and inoperable groups. Conclusion: SMART allows safe delivery of an ablative dose of radiotherapy, with minimal treatment-related toxicity, even in previously resected or irradiated patients. In this real-world cohort, local control with complete response was achieved by 20% of the patients. Further studies are needed to evaluate long-term outcome and late toxicity.

Undetected Pancreatic Adenocarcinoma on Computed Tomography: Frequency According to Scan Protocol.

BACKGROUND: Computed tomography (CT) is the main diagnostic modality for detecting pancreatic adenocarcinoma. OBJECTIVES: To assess the frequency of missed pancreatic adenocarcinoma on CT scans according to different CT protocols. METHODS: The medical records of consecutive pancreatic adenocarcinoma patients were retrospectively collected (12/2011-12/2015). Patients with abdominal CT scans performed up to a year prior to cancer diagnosis were included. Two radiologists registered the presence of radiological signs of missed cancers. The frequency of missed cancers was compared between portal and pancreatic/triphasic CT protocols. RESULTS: Overall, 180 CT scans of pancreatic adenocarcinoma patients performed prior to cancer diagnosis were retrieved; 126/180 (70.0%) were conducted using pancreatic/triphasic protocols and 54/180 (30.0%) used portal protocols. The overall frequency of missed cancers was 6/180 (3.3%) in our study population. The frequency of missed cancers was higher with the portal CT protocols compared to the pancreatic/triphasic protocols: 5/54 (9.3%) vs. 1/126 (0.8%), P = 0.01. CT signs of missed cancers included small hypodense lesions, peri-pancreatic fat stranding, and dilated pancreatic duct with a cut-off sign. CONCLUSIONS: The frequency of missed pancreatic adenocarcinoma is higher on portal CT protocols. Physicians should consider the cancer miss rate on different CT protocols.

MRI features of intraductal papillary mucinous neoplasm of the bile ducts, "The myth about the cyst": A systematic review.

Rationale and objectives: Intraductal papillary mucinous neoplasm of the bile ducts (IPMN-B) is a true pre-cancerous lesion, which shares common features with pancreatic IPMN (IPMN-P). While IPMN-P is a well described entity for which guidelines were formulated and revised, IPMN-B is a poorly described entity.We carried out a systematic review to evaluate the existing literature, emphasizing the role of MRI in IPMN-B depiction. Materials and methods: PubMed database was used to identify original studies and case series that reported MR Imaging features of IPMN-B. The search keywords were "IPMN OR intraductal papillary mucinous neoplasm OR IPNB OR intraductal papillary neoplasm of the bile duct AND Biliary OR biliary cancer OR hepatic cystic lesions". Risk of bias and applicability were evaluated using the QUADAS-2 tool. Results: 884 Records were Identified through database searching. 12 studies satisfied the inclusion criteria, resulting in MR features of 288 patients. All the studies were retrospective. Classic features of IPMN-B are under-described. Few studies note worrisome features, concerning for an underlying malignancy. 50 % of the studies had a high risk of bias and concerns regarding applicability. Conclusions: The MRI features of IPMN-B are not well elaborated and need to be further studied. Worrisome features and guidelines regarding reporting the imaging findings should be established and published. Radiologists should be aware of IPMN-B, since malignancy diagnosis in an early stage will yield improved prognosis.

Perivascular Cuffing as the Sole Imaging Finding of Pancreatic Cancer.

BACKGROUND: Perivascular cuffing as the sole imaging manifestation of pancreatic ductal adenocarcinoma (PDAC) is an under-recognized entity. OBJECTIVES: To present this rare finding and differentiate it from retroperitoneal fibrosis and vasculitis. METHODS: Patients with abdominal vasculature cuffing were retrospectively collected (January 2011 to September 2017). We evaluated vessels involved, wall thickness, length of involvement and extra-vascular manifestations. RESULTS: Fourteen patients with perivascular cuffing were retrieved: three with celiac and superior mesenteric artery (SMA) perivascular cuffing as the only manifestation of surgically proven PDAC, seven with abdominal vasculitis, and four with retroperitoneal fibrosis. PDAC patients exhibited perivascular cuffing of either or both celiac and SMA (3/3). Vasculitis patients showed aortitis with or without iliac or SMA cuffing (3/7) or cuffing of either or both celiac and SMA (4/7). Retroperitoneal fibrosis involved the aorta (4/4), common iliac (4/4), and renal arteries (2/4). Hydronephrosis was present in 3/4 of retroperitoneal fibrosis patients. PDAC and vasculitis demonstrated reduced wall thickness in comparison to retroperitoneal fibrosis (PDAC: 1.0 ± 0.2 cm, vasculitis: 1.2 ± 0.5 cm, retroperitoneal fibrosis: 2.4 ± 0.4 cm; P = 0.002). There was no significant difference in length of vascular involvement (PDAC: 6.3 ± 2.1 cm, vasculitis: 7.1 ± 2.6 cm, retroperitoneal fibrosis: 8.7 ± 0.5 cm). CONCLUSIONS: Celiac and SMA perivascular cuffing can be the sole finding in PDAC and may be indistinguishable from vasculitis. This entity may differ from retroperitoneal fibrosis as it spares the aorta, iliac, and renal arteries and demonstrates thinner walls and no hydronephrosis.

Outcome of the first 200 patients with prostate cancer treated with MRI-Linac at Assuta MC.

Background: We present our experience with MR-guided stereotactic body radiotherapy (SBRT) for 200 consecutive patients with prostate cancer with minimum 3-month follow-up. Methods: Treatment planning included fusion of the 0.35-Tesla planning MRI with multiparametric MRI and PET-PSMA for Group Grade (GG) 2 or higher and contour review with an expert MRI radiologist. No fiducials or rectal spacers were used. Prescription dose was 36.25 Gy in 5 fractions over 2 weeks to the entire prostate with 3-mm margins. Daily plan was adapted if tumor and organs at risk (OAR) doses differed significantly from the original plan. The prostate was monitored during treatment that was automatically interrupted if the target moved out of the PTV range. Results: Mean age was 72 years. Clinical stage was T1c, 85.5%; T2, 13%; and T3, 1.5%. In addition, 20% were GG1, 50% were GG2, 14.5% were GG3, 13% were GG4, and one patient was GG5. PSA ranged from 1 to 77 (median, 6.2). Median prostate volume was 57cc, and 888/1000 (88%) fractions required plan adaptation. The most common acute GU toxicity was Grade I, 31%; dysuria and acute gastrointestinal toxicity were rare. Three patients required temporary catheterization. Prostate size of over 100cc was associated with acute fatigue, urinary hesitance, and catheter insertion. Prostate Specific Antigen (PSA) decreased in 99% of patients, and one patient had regional recurrence. Conclusion: MR-guided prostate SBRT shows low acute toxicity and excellent short-term outcomes. Real-time MRI ensures accurate positioning and SBRT delivery.

Diffusion-weighted MRI for predicting and assessing treatment response of liver metastases from CRC - A systematic review and meta-analysis.

The evaluation of response to chemotherapy and targeted therapies in colorectal liver metastases has traditionally been based on size changes, as per the RECIST criteria. However, therapy may alter tissue composition and not only tumor size, therefore, functional imaging techniques such as diffusion-weighted magnetic resonance imaging (DWI) may offer a more comprehensive assessment of treatment response. The aim of this systematic review and meta-analysis was to evaluate the use of DWI in the prediction and assessment of response to treatment in colorectal liver metastases and to determine if there is a baseline apparent diffusion coefficient (ADC) cut-off value that can predict a favorable response. A literature search was conducted using the MEDLINE/PubMed database, and risk of bias was evaluated using the QUADAS-2 tool. The mean differences between responders and non-responders were pooled. A total of 16 studies met the inclusion criteria, and various diffusion-derived techniques and coefficients were found to have potential for predicting and assessing treatment response. However, discrepancies were noted between studies. The most consistent predictor of response was a lower baseline ADC value calculated using traditional mono-exponential methods. Non-mono-exponential techniques for calculating DWI-derived parameters were also reported. A meta-analysis of a subset of studies failed to establish a cut-off value of ADC due to heterogeneity, but revealed a pooled mean difference of -0.12 × 10-3 mm2/s between responders and non-responders. The results of this systematic review suggest that diffusion-derived techniques and coefficients may contribute to the evaluation and prediction of treatment response in colorectal liver metastases. Further controlled prospective studies are needed to confirm these findings and to guide clinical and radiological decision-making in the management of patients with CRC liver metastases.

The Role of 68 Ga-FAPI PET/CT in Detection of Metastatic Lobular Breast Cancer.

PURPOSE: Invasive lobular breast cancer (ILC) may be hard to detect using conventional imaging modalities and usually shows less avidity to 18 F-FDG PET/CT. 68 Ga-fibroblast activation protein inhibitor (FAPI) PET/CT has shown promising results in detecting non- 18 F-FDG-avid cancers. We aimed to assess the feasibility of detecting metastatic disease in patients with non- 18 F-FDG-avid ILC. METHODS: This prospective study included patients with metastatic ILC, infiltrative to soft tissues, which was not 18 F-FDG avid. The patients underwent 68 Ga-FAPI PET/CT for evaluation, which was correlated with the fully diagnostic CT performed at the same time. RESULTS: Seven women (aged 57 ± 10 years) were included. Among the 30 organs and structures found to be involved by tumor, the number of findings observed by FAPI PET/CT was significantly higher than that observed by CT alone ( P = 0.022), especially in infiltrative soft tissue and serosal locations. CONCLUSIONS: This small pilot trial suggests a role for 68 Ga-FAPI PET/CT in ILC, which needs to be confirmed by subsequent trials.

Palliative urinary diversion in patients with malignant ureteric obstruction due to gynaecological cancer.

OBJECTIVES: To identify factors aiding the selection of patients with gynaecological cancer with malignant urinary obstruction who are least likely to benefit from palliative urinary diversion (UD), and to create a risk-stratification model for decision-making. METHODS: This historic cohort study comprised 74 consecutive patients with urinary obstruction resulting from gynaecological malignancies. All underwent palliative UD by percutaneous nephrostomy (PCN). Using the Cox proportional hazards regression model and Kaplan-Meier curves with the log-rank test, we developed a prognostic score identifying candidates least likely to benefit from the intervention. RESULTS: The median follow-up was 4.72 (range 0-5.71) years. Hydronephrosis was diagnosed in most patients on recurrent or persistent disease (81%). It was bilateral in 37.8%. Intervention-related complications included urinary sepsis (8%), catheter dislodgment requiring replacement (17%) and gross haematuria necessitating blood transfusions (13%). After PCN, conversion to an internal ureteral stent was feasible in 46%. The median survival was 11.13 (range 0-67) months. Two patients died within a month of UD. Multivariate analysis identified diabetes mellitus (DM), poor Eastern Cooperative Oncology Group (ECOG) performance status >1 and ascites as significant negative survival factors. A prognostic index based on those factors identified the short-term and long-term survivors. Risk factor-based mortality HRs were 11.37 (95% CI 4.12 to 31.37) with one factor, 26.57 (95% CI 9.14 to 77.26) with two factors and 67.25 (95% CI 15.6 to 289.63) with three factors (all with p<0.0001). CONCLUSIONS: Our proposed prognostic index, based on ascites, ECOG performance status and DM, might help select patients with gynaecological cancer least likely to benefit from palliative UD.

Spontaneous versus morcellator-related benign metastasizing leiomyoma-A retrospective study.

OBJECTIVE: To compare characteristics, disease course, and prognosis of spontaneous versus iatrogenic benign metastasizing leiomyoma (BML). METHODS: A retrospective cohort study comparing iatrogenic and spontaneous BML. RESULTS: Twenty cases were included, 12 (60%) spontaneous and 8 (40.0%) iatrogenic with a median follow up of 3.4 years. The rate of asymptomatic presentation did not differ between study groups (P = 0.157). When symptoms occurred, dyspnea was more common in the spontaneous group (66.6% vs 0%, P = 0.023) and self-palpation was more common in the iatrogenic group (57.1% vs 0%, P = 0.023). Intravascular masses were more common in the spontaneous group (66.6% vs 0%, P = 0.029). Rate of BML located in abdominal/pelvic cavity was higher in the iatrogenic group (100.0% vs 41.6%, P = 0.014). Of the 12 women in the spontaneous group, 50% had recurrent disease following surgical resection or unresectable lesions surgical resection was successfully attempted in seven of the eight (87.5%) women in the iatrogenic group, with no residual/recurrent disease. None of the patients died of her disease. CONCLUSION: Spontaneous and iatrogenic BML can probably be regarded as two separate etiologies of the same pathologic phenomenon, usually with favorable prognosis. However, spontaneous BML may have a less favorable course.

The association between adrenal adenoma size, autonomous cortisol secretion and metabolic derangements.

OBJECTIVE: Autonomous cortisol secretion (ACS) is common in patients with adrenal incidentalomas (AI). ACS is associated with increased cardiovascular morbidity and mortality. Data regarding the association between radiological characteristics of adrenal adenomas, their hormonal functionality and metabolic outcomes, are scarce and inconclusive. In this study, we aim to delineate the association between radiological characteristics of AI, ACS and metabolic status. METHODS: A cross-sectional study of 77 patients with AI who underwent a comprehensive hormonal evaluation. Radiological assessments were performed by an independent radiologist blinded to the clinical and hormonal phenotype of each case. Linear regression models were used to evaluate the association between post dexamethasone suppression test (DST) cortisol levels, metabolic indices and radiological measurements. RESULTS: Mean maximal adenoma diameter was greater in patients with versus without ACS (20.35 ± 6 vs. 27.09 ± 9.3 mm, respectively, p < .01). Maximal adenoma diameter was found to be positively and linearly correlated with post-DST morning cortisol levels across their entire range (R = .474, p < .01). Linear correlations between maximal adenoma diameter and indices of glycemic control showed a correlation coefficient (R) of .481 and .463 for fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c), respectively, p < .01. When analysis included only patients with ACS, an R = .584 and R = .565 was observed for FPG and HbA1c, respectively (p < .01 for both). The association between maximal adenoma diameter and both FPG and post-DST morning cortisol intensified in patients with metabolic syndrome. CONCLUSION: There is a quantitative positive mild correlation between AI size and both cortisol autonomy and metabolic parameters.

Clinical Significance of Pancreatic Atrophy Induced by Immune-Checkpoint Inhibitors: A Case-Control Study.

Immune-checkpoint inhibitor (ICI)-related diarrhea is attributed to inflammatory colitis, with no other drug-related differential diagnosis. Here, we investigated the occurrence of pancreatic atrophy (PA) in ICI-treated cancer patients and its correlation to exocrine pancreatic insufficiency (EPI). Metastatic melanoma, non-small cell lung carcinoma, and head and neck squamous cell carcinoma patients (n = 403) treated with anti-PD-1 (n = 356) or anti-CTLA-4 (n = 47) were divided into a case group (radiologic evidence of PA); control group matched by age, gender, and previous lines of treatment; and colitis group (ICI-induced colitis). Quantitative pancreatic volumetry was used for calculation of the decrease in pancreatic volume over time (atrophy rate). Thirty-one patients (7.7%) developed PA compared with 41 matched controls (P = 0.006). Four patients developed EPI, all from the anti-PD-1-treated group, which resolved with oral enzyme supplementation. The atrophy rate did not correlate with EPI (P = 0.87). EPI-related diarrhea presented at a median of 9 months, whereas the diarrhea of anti-PD-1-induced colitis patients (n = 22) was presented at a median of 2 months (P = 0.029). ICI-induced PA is irreversible and can result in EPI. EPI should be suspected in cases of late-onset steroid-resistant diarrhea with features of steatorrhea and treated with oral enzyme supplements.

Gynecological Lymphoma: A Case Series and Review of the Literature.

OBJECTIVE: The aim of the study was to evaluate the radiological characteristics of gynecological lymphoproliferative disease (LPD) and specific imaging features that may suggest the diagnosis. METHODS: Two readers conducted a retrospective evaluation of imaging studies of 13 female patients presenting with a gynecological LPD. A literature review was also performed. RESULTS: Of the 13 evaluated women, 9 had ovarian involvement, 3 had cervical involvement, and 1 had uterine involvement. The most common lesion characteristics were homogenous masses (11), with mild contrast enhancement (9), followed by soft-tissue necrosis (4), prominent blood vessels displaced by the lesions (4), linear arrangement of cysts at the periphery of the ovaries (3), and "touching" ovaries in all cases of bilateral ovarian involvement. CONCLUSIONS: A solid large homogeneous mass with mild contrast enhancement should alert the radiologist to the possibility of the differential diagnosis of LPD. Radiologists should be "the gatekeepers" by raising this possibility to avoid unnecessary surgery and enable appropriate treatment.

Fat necrosis after abdominal surgery: A pitfall in interpretation of FDG-PET/CT.

OBJECTIVE: We describe FDG-PET/CT findings of postoperative fat necrosis in patients following abdominal surgery, and evaluate their changes in size and FDG uptake over time. METHODS: FDG-PET/CT scans from January 2007-January 2016 containing the term 'fat necrosis' were reviewed. Lesions meeting radiological criteria of fat necrosis in patients with prior abdominal surgery were included. RESULTS: Forty-four patients, 30 males, mean age 68.4 ± 11.0 years. Surgeries: laparotomy (n=37; 84.1 %), laparoscopy (n=3; 6.8 %), unknown (n=4; 9.1 %). CTs of all lesions included hyperdense well-defined rims surrounding a heterogeneous fatty core. Sites: peritoneum (n=34; 77 %), omental fat (n=19; 43 %), subcutaneous fat (n=8; 18 %), retroperitoneum (n=2; 5 %). Mean lesion long axis: 33.6±24.9 mm (range: 13.0-140.0). Mean SUVmax: 2.6±1.1 (range: 0.6-5.1). On serial CTs (n=34), lesions decreased in size (p=0.022). Serial FDG-PET/CT (n=24) showed no significant change in FDG-avidity (p=0.110). Mean SUVmax did not correlate with time from surgery (p=0.558) or lesion size (p=0.259). CONCLUSION: Postsurgical fat necrosis demonstrated characteristic CT features and may demonstrate increased FDG uptake. However, follow-up of subsequent imaging scans showed no increases in size or FDG-avidity. Awareness of this entity is important to avoid misinterpretation of findings as recurrent cancer. KEY POINTS: • Postsurgical fat necrosis may mimic cancer in FDG-PET/CT. • Follow-up of fat necrosis showed no increase in FDG intensity. • CT follow-up showed a decrease in lesion size. • FDG uptake did not correlate with time lapsed from surgery.

Physiologic uptake of 18F-FDG in transposed ovaries may mimic metastasis on 18F-FDG PET/CT imaging.

BACKGROUND: Ovarian transposition is aimed at preserving ovarian function before irradiation in pelvic malignancies. The extrapelvic location of the ovaries and their physiologic fluorine-18-fluorodeoxyglucose (F-FDG)-uptake is a potential source of misdiagnosis as metastasis on F-FDG PET/CT. We describe the F-FDG PET/CT characteristics of transposed ovaries and their changes over time. PATIENTS AND METHODS: We reviewed F-FDG PET/CT studies of all consecutive women with pelvic malignancies who underwent ovarian transposition between 2007 and 2013. Studies were grouped according to the time period over which they were carried out. Findings were categorized by location, size, appearance (solid/mixed/cystic), presence of surgical clips, ovarian F-FDG uptake (maximum standardized uptake value), and attenuation values on CT (Hounsfield units). Group time-period differences were assessed. RESULTS: Seventy-nine F-FDG PET/CT studies were reviewed, 30 before and 49 after transposition. Time-period groups after transposition were up to 4 months (18 studies), 4.1-12 months (n=14), and more than 12 months (n=17). After transposition, ovaries were located mainly in the paracolic gutter (n=32) and subhepatic regions (n=18). Surgical clips were present in 67%. Both ovaries appeared more solid 1 year after surgery than preoperatively (13.7% before vs. 61.3% after surgery; P<0.001). Transient F-FDG-avidity was observed in 11 ovaries. Hounsfield unit values were higher within 4 months after surgery than preoperatively, reverting thereafter to preoperative values. CONCLUSION: After ovarian transposition, nonanatomic location, loss of cysts formation in favor of solid appearance over time, and intermittent F-FDG uptake of functioning transposed ovaries might mimic metastatic lesions. Careful interpretation of F-FDG PET/CT findings is mandatory in women with pelvic malignancies who have undergone ovarian transposition.

Intraluminal Uterine Hypodensity in CT Scans of Postmenopausal Women: Recommendations for Interpretation.

OBJECTIVE: This study aims to investigate the association between intraluminal uterine hypodensity and uterine malignancy and establish thresholds that would minimize routine gynecological evaluation. METHODS: Two groups were recruited retrospectively: cancer group, which comprised 32 sequential endometrial cancer patients, and postmenopausal group, which comprised 63 women, with no known gynecologic malignancy.Two radiologists independently measured hypodensity, transversely in the axial plane and anterioposteriorly in the sagittal plane.The association between cancer and hypodensity was evaluated. Receiver operating characteristic curves were evaluated diameters predictive of cancer. RESULTS: Hypodensity was associated with cancer (cancer group, 93.8% vs. postmenopausal group, 38.1%; P < 0.0001). Hypodensity diameters correlated highly with prediction of cancer (transverse area under the curve, 0.899; anteroposterior area under the curve, 0.892). Diameters of 19.5 mm transverse and 6.0 mm anteroposterior yielded a sensitivity of 87% and 83% and specificity of 91% and 83%, respectively. CONCLUSIONS: Intrauterine hypodensity is a common finding in computed tomography scans of postmenopausal women. A transverse diameter of 19.5 mm and an anteroposterior diameter of 6.0 mm are suggested as thresholds for further gynecological sonographic evaluation.

Role of Emergency Magnetic Resonance Imaging for the Workup of Suspected Appendicitis in Pregnant Women.

BACKGROUND: Pregnant women with acute abdominal pain pose a diagnostic challenge. Delay in diagnosis may result in significant risk to the fetus. The preferred diagnostic modality is magnetic resonance imaging (MRI), since ultrasonography is often inconclusive, and computed tomography (CT) would expose the fetus to ionizing radiation. OBJECTIVES: To describe the process in setting up an around-the-clock MRI service for diagnosing appendicitis in pregnant women and to evaluate the contribution of abdominal MR in the diagnosis of acute appendicitis. METHODS: We conducted a retrospective study of consecutive pregnant women presenting with acute abdominal pain over a 6 year period who underwent MRI studies. A workflow that involved a multidisciplinary team was developed. A modified MRI protocol adapted to pregnancy was formulated. Data regarding patients' characteristics, imaging reports and outcome were collected retrospectively. RESULTS: 49 pregnant women with suspected appendicitis were enrolled. Physical examination was followed by ultrasound: when positive, the patients were referred for MR scan or surgery treatment; when the ultrasound was inconclusive, MR scan was performed. In 88% of women appendicitis was ruled out and surgery was prevented. MRI diagnosed all cases with acute appendicitis and one case was inconclusive. The overall statistical performance of the study shows a negative predictive value of 100% (95%CI 91.9-100%) and positive predictive value of 83.3% (95%CI 35.9-99.6%). CONCLUSIONS: Creation of an around-the-clock imaging service using abdominal MRI with the establishment of a workflow chart using a dedicated MR protocol is feasible. It provides a safe way to rule out appendicitis and to avoid futile surgery in pregnant women.

Main Imaging Features of Crohn's Disease: Agreement between MR-Enterography and CT-Enterography.

BACKGROUND: Only a few studies have compared the accuracy of magnetic resonance enterography (MRE) and computed tomography enterography (CTE) in the diagnosis of Crohn's disease and its complications. OBJECTIVES: To compare the sensitivity of MRE and CTE analysis in their ability to detect, sign-by-sign, 10 classical imaging signs of Crohn's disease. METHODS: The study group comprised 42 biopsy-proven Crohn's disease patients who underwent both CTE and MRE within an average period of 6 weeks. Agreement between the two modalities in detecting the 10 most significant radiological signs of CD was evaluated using the Kappa index. The sensitivity of MRE and CTE was calculated using a standard of reference composed of all the findings seen by CTE and/or MRE. We analyzed MRE and CTE sensitivity separately in two groups, according to the time interval between the examinations. RESULTS: Agreement between CTE and MRE was more than 70% in 8 of the 10 signs: mural thickening, phlegmon, stenosis, skip lesions, mucosal stratification, fistula, abscess, and creeping fat. The Kappa level of agreement values for CTE versus MRE varied between substantial for phlegmon and skip lesions; moderate for fistula, creeping fat, abscess and mural thickening; and fair for stenosis and dilatation. CTE detected more findings than MRE, except for creeping fat and fistula. There was no significant difference in the sensitivity of CTE and MRE in the two groups defined by the time interval (time < 1.5 and time > 1.5 months) except for detection of dilatation. CONCLUSIONS: Almost all imaging signs of Crohn's disease were detected equally well by both modalities regardless of the time interval between examinations. We therefore consider MRE to be reliable for imaging and follow-up in patients with Crohn's disease who may need recurrent imaging.

Diffusion tensor magnetic resonance imaging of the pancreas.

PURPOSE: To develop a diffusion-tensor-imaging (DTI) protocol that is sensitive to the complex diffusion and perfusion properties of the healthy and malignant pancreas tissues. MATERIALS AND METHODS: Twenty-eight healthy volunteers and nine patients with pancreatic-ductal-adenocacinoma (PDAC), were scanned at 3T with T2-weighted and DTI sequences. Healthy volunteers were also scanned with multi-b diffusion-weighted-imaging (DWI), whereas a standard clinical protocol complemented the PDAC patients' scans. Image processing at pixel resolution yielded parametric maps of three directional diffusion coefficients λ1, λ2, λ3, apparent diffusion coefficient (ADC), and fractional anisotropy (FA), as well as a λ1-vector map, and a main diffusion-direction map. RESULTS: DTI measurements of healthy pancreatic tissue at b-values 0,500 s/mm² yielded: λ1 = (2.65±0.35)×10⁻³, λ2 = (1.87±0.22)×10⁻³, λ3 = (1.20±0.18)×10⁻³, ADC = (1.91±0.22)×10⁻³ (all in mm²/s units) and FA = 0.38±0.06. Using b-values of 100,500 s/mm² led to a significant reduction in λ1, λ2, λ3 and ADC (p<.0001) and a significant increase (p<0.0001) in FA. The reduction in the diffusion coefficients suggested a contribution of a fast intra-voxel-incoherent-motion (IVIM) component at b≤100 s/mm², which was confirmed by the multi-b DWI results. In PDACs, λ1, λ2, λ3 and ADC in both 0,500 s/mm² and 100,500 s/mm² b-values sets, as well as the reduction in these diffusion coefficients between the two sets, were significantly lower in comparison to the distal normal pancreatic tissue, suggesting higher cellularity and diminution of the fast-IVIM component in the cancer tissue. CONCLUSION: DTI using two reference b-values 0 and 100 s/mm² enabled characterization of the water diffusion and anisotropy of the healthy pancreas, taking into account a contribution of IVIM. The reduction in the diffusion coefficients of PDAC, as compared to normal pancreatic tissue, and the smaller change in these coefficients in PDAC when the reference b-value was modified from 0 to 100 s/mm², helped identifying the presence of malignancy.