[Pancreas divisum and pancreatitis]. / Pankreas divisum und Pankreatitis.

CLINICAL/METHODOLOGICAL ISSUE: Diagnostic and clinical relevance of pancreas divisum. STANDARD RADIOLOGICAL METHODS: Ultrasonography (US), magnetic resonance cholangiopancreatography (MRCP), magnetic resonance imaging (MRI), computed tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP). PERFORMANCE: Pancreas divisum is an anatomic variation of pancreatic duct system with an incidence in general population of about 10%. It can become symptomatic in approximately 5% of patients. MRI with MRCP is the method of choice to diagnose pancreas divisum. ACHIEVEMENTS: MRCP is equal to ERCP in diagnosing pancreas divisum in routine clinical practice as it is noninvasive, offers the possibility to evaluate the adjacent tissues and has almost no contraindications. PRACTICAL RECOMMENDATIONS: It is important to be familiar with the anatomy of the pancreatic duct system in order to plan interventional procedures for symptomatic patients in due time.

Radiological evaluation of pancreatic cancer: What is the significance of arterial encasement >180° after neoadjuvant treatment?

PURPOSE: This study aimed to evaluate contrast-enhanced computed tomography (CE-CT) features for prediction of arterial tumor invasion in pancreatic cancer (PDAC) patients in the event of arterial encasement >180° after neoadjuvant (radio-)chemotherapy (NAT). METHODS: Seventy PDAC patients with seventy-five arteries showing encasement >180° after completion of NAT were analyzed. All patients underwent surgical exploration with either tumor resection including arterial resection, periadventitial dissection (arterial divestment) or confirmation of locally irresectable disease. CE-CT scans were assessed regarding tumor extent and artery-specific imaging features. The results were analyzed on a per-artery basis. Based on the intraoperative and histopathological findings, encased arteries were classified as either invaded or non-invaded. RESULTS: Eighteen radiologically encased arteries were resected; of these, nine had pathologic evidence for tumor invasion. In 42 encased arteries, the tumor could be removed by arterial divestment. In 13 patients with 15 encased arteries, the tumor was deemed technically irresectable. Median tumor size, length of solid soft tissue contact, and degree of circumferential contiguity by solid soft tissue along the artery in CE-CT were significantly lower in the non-invaded than in the invaded artery group (p ≤ 0.017). Imaging features showed moderate accuracies for prediction of arterial invasion (≤72.0 %). The thresholds ≤26 mm for post-NAT solid soft tissue contact and ≤270° for circumferential contiguity by solid soft tissue had high negative predictive values (≥87.5 %). CONCLUSION: Although post-NAT prediction of arterial invasion remains difficult, arteries with ≤270° contiguity by soft tissue and arteries with ≤26 mm length of solid soft tissue contact are unlikely to be invaded, with possible implications for surgical planning.

Dual-Energy Perfusion-CT in Recurrent Pancreatic Cancer - Preliminary Results.

PURPOSE: To evaluate the diagnostic performance of dual energy (DE) perfusion-CT for the differentiation between postoperative soft-tissue formation and tumor recurrence in patients after potentially curative pancreatic cancer resection. MATERIAL AND METHODS: 24 patients with postoperative soft-tissue formation in the conventional regular follow-up CT acquisition after pancreatic cancer resection with curative intent were included prospectively. They were examined with a 64-row dual-source CT using a dynamic sequence of 34 DE acquisitions every 1.5 s (80 ml of iodinated contrast material, 370 mg/ml, flow rate 5 ml/s). Weighted average (linearly blended M0.5) 120kVp-equivalent dual-energy perfusion image data sets were evaluated with a body-perfusion CT tool (see above) for estimating blood flow, permeability, and blood volume. Diagnosis was confirmed by histological study (n = 4) and by regular follow-up. RESULTS: Final diagnosis was local recurrence of pancreatic cancer in 15 patients and unspecific postoperative tissue formation in 9 patients. The blood-flow values for recurrence tissue trended to be lower compared to postoperative tissue formation with 16.6 ml/100 ml/min and 24.7 ml/100 ml/min, respectively for weighted average 120kVp-equivalent image data, which was not significant (n.s.) (p = 0.06, significance level 0.05). Permeability- and blood-volume values were only slightly lower in recurrence tissue (n.s.). CONCLUSION: DE perfusion-CT is feasible in patients after pancreatic cancer resection and a promising functional imaging technique. As only a trend for lower perfusion values in local recurrence compared to unspecific postoperative alterations was found, the perfusion differences are not yet sufficient to differentiate between malignancy and unspecific postoperative alterations for this new technique. Further studies and technical improvements are needed to generate reliable data for this clinically highly relevant differentiation. KEY POINTS: • DE Perfusion CT is feasible in patients after pancreatic cancer resection.• While reliable differentiation of unspecific postoperative tissue formation from recurrent malignancy cannot be achieved yet, it is within reach.• DE Perfusion CT has the potential to overcome todays limitations of pure morphological diagnosis of recurrent pancreatic cancer. Citation Format: • Fritz F, Skornitzke S, Hackert T et al. Dual-Energy Perfusion-CT in Recurrent Pancreatic Cancer - Preliminary RESULTS. Fortschr Röntgenstr 2016; 188: 559 - 565.

[Diagnostic strategy and differential therapeutic approach for cystic lesions of the pancreas]. / Diagnostische Strategie und differenzialtherapeutisches Vorgehen bei zystischen Läsionen des Pankreas.

CLINICAL/METHODICAL ISSUE: Cystic pancreatic lesions (CPL) are diagnosed with increasing frequency. Because up to 60% of CPL are classified as malignant or premalignant, every CPL should be fully investigated and clarified. Serous CPL with low risk of malignancy must be differentiated from mucinous CPL with relevant potential malignancy (intraductal papillary mucinous neoplasm IPMN) and mucinous cystic neoplasm (MCN) as well as from harmless pseudocysts. STANDARD RADIOLOGICAL METHODS: Cross-sectional imaging with computed tomography (CT) and magnetic resonance imaging (MRI) plays a crucial role in the diagnostics of CPL. METHODICAL INNOVATIONS: An algorithm for the differential diagnostic classification of CPL is presented. PERFORMANCE: The connection to the pancreatic duct is the key diagnostic criterion to differentiate IPMN from all other CPL. An exception to this rule is that pseudocysts can also show a connection to the pancreatic duct. A further classification of CPL with no connection to the pancreatic duct can be made by morphological criteria and correlation of the radiological findings with patient age, sex, history and symptoms. PRACTICAL RECOMMENDATIONS: Depending on the diagnosis and hence the malignant potential the indications for surgery or watch and wait have to be discussed in an interdisciplinary cooperation. Due to its higher soft tissue contrast MRI is often superior to CT for depiction of CPL morphology.

Risk of pancreatic fistula after enucleation of pancreatic tumours.

BACKGROUND: Enucleation is used increasingly for small pancreatic tumours. Data on perioperative outcome after pancreatic enucleation, especially regarding the significance and risk factors associated with postoperative pancreatic fistula (POPF), are limited. This study aimed to assess risk-dependent perioperative outcome after pancreatic enucleation, with a focus on POPF. METHODS: Patients undergoing enucleation for pancreatic lesions between October 2001 and February 2014 were identified from a prospective database. A detailed analysis of morbidity was performed. Risk factors for POPF were assessed by univariable and multivariable analyses. RESULTS: Of 166 enucleations, 94 (56.6 per cent) were performed for cystic and 72 (43.4 per cent) for solid lesions. Morbidity was observed in 91 patients (54.8 per cent). Severe complications occurred in 30 patients (18.1 per cent), and one patient (0.6 per cent) died. Reoperation was necessary in nine patients (5.4 per cent). POPF was the main determinant of outcome and occurred in 68 patients (41.0 per cent): grade A POPF, 34 (20.5 per cent); grade B, ten (6.0 per cent); and grade C, 24 (14.5 per cent). Risk factors independently associated with POPF were: cystic tumour, localization in the pancreatic tail, history of pancreatitis and cardiac co-morbidity. Only cystic morphology was independently associated with clinically relevant POPF (grade B or C), occurring after enucleation in 25 (27 per cent) of 94 patients with cystic tumours versus nine (13 per cent) of 72 patients with solid tumours. Tumour size and distance to the main duct were not associated with risk of POPF. CONCLUSION: Enucleation is a safe procedure in appropriately selected patients with a low rate of severe complications. POPF is the main determinant of outcome and is more frequent after the enucleation of cystic lesions.

Qualitative and quantitative evaluation of rigid and deformable motion correction algorithms using dual-energy CT images in view of application to CT perfusion measurements in abdominal organs affected by breathing motion.

OBJECTIVE: To compare six different scenarios for correcting for breathing motion in abdominal dual-energy CT (DECT) perfusion measurements. METHODS: Rigid [RRComm(80 kVp)] and non-rigid [NRComm(80 kVp)] registration of commercially available CT perfusion software, custom non-rigid registration [NRCustom(80 kVp], demons algorithm) and a control group [CG(80 kVp)] without motion correction were evaluated using 80 kVp images. Additionally, NRCustom was applied to dual-energy (DE)-blended [NRCustom(DE)] and virtual non-contrast [NRCustom(VNC)] images, yielding six evaluated scenarios. After motion correction, perfusion maps were calculated using a combined maximum slope/Patlak model. For qualitative evaluation, three blinded radiologists independently rated motion correction quality and resulting perfusion maps on a four-point scale (4 = best, 1 = worst). For quantitative evaluation, relative changes in metric values, R(2) and residuals of perfusion model fits were calculated. RESULTS: For motion-corrected images, mean ratings differed significantly [NRCustom(80 kVp) and NRCustom(DE), 3.3; NRComm(80 kVp), 3.1; NRCustom(VNC), 2.9; RRComm(80 kVp), 2.7; CG(80 kVp), 2.7; all p < 0.05], except when comparing NRCustom(80 kVp) with NRCustom(DE) and RRComm(80 kVp) with CG(80 kVp). NRCustom(80 kVp) and NRCustom(DE) achieved the highest reduction in metric values [NRCustom(80 kVp), 48.5%; NRCustom(DE), 45.6%; NRComm(80 kVp), 29.2%; NRCustom(VNC), 22.8%; RRComm(80 kVp), 0.6%; CG(80 kVp), 0%]. Regarding perfusion maps, NRCustom(80 kVp) and NRCustom(DE) were rated highest [NRCustom(80 kVp), 3.1; NRCustom(DE), 3.0; NRComm(80 kVp), 2.8; NRCustom(VNC), 2.6; CG(80 kVp), 2.5; RRComm(80 kVp), 2.4] and had significantly higher R(2) and lower residuals. Correlation between qualitative and quantitative evaluation was low to moderate. CONCLUSION: Non-rigid motion correction improves spatial alignment of the target region and fit of CT perfusion models. Using DE-blended and DE-VNC images for deformable registration offers no significant improvement. ADVANCES IN KNOWLEDGE: Non-rigid algorithms improve the quality of abdominal CT perfusion measurements but do not benefit from DECT post processing.

[Capabilities of computed tomography to evaluate polymorphic changes in destructive pancreatitis].

OBJECTIVE: To determine whether the lower-density pancreatic parenchymal areas detected by a computed tomography (CT) study in patients with acute pancreatitis correspond to the necrotic portions of the gland or whether these changes may be reversal. MATERIAL AND METHODS: The investigation covered 25 patients who had undergone or dynamic CT studies made at different time intervals. Two independent investigators with 4 and 19 years of experience retrospectively analyzed the results of both CT studies. Target estimation was made of the extent (volume) of and CT density changes in the hypodense areas of the gland parenchyma. RESULTS: Seven (28%) of the 25 patients were noted to have higher CT density in the areas that had decreased density during primary CT studies (more than a 30 HU increase was rated as significant). There was a statistically significant difference between the patient groups when comparing the extent of hypodense areas and the difference in CT density (t-test, p = 0.006); Mann-Whitney U-test, p = 0.01 for extent difference and t-test, p = 0.00; Mann-Whitney U-test, p = 0.00 for CT density difference. There was also a correlation between the extent of hypodense areas and the difference in their CT density (Pearson: r = -0.533, p = 0.006; Spearman: r = -0.636, p = 0.001). CONCLUSION: The results of our investigation may suggest that the lower-density pancreatic parenchymal areas cannot always correspond to necrotic changes and may be reversible.

Dual-energy perfusion-CT of pancreatic adenocarcinoma.

PURPOSE: To evaluate the feasibility of dual-energy CT (DECT)-perfusion of pancreatic carcinomas for assessing the differences in perfusion, permeability and blood volume of healthy pancreatic tissue and histopathologically confirmed solid pancreatic carcinoma. MATERIALS AND METHODS: 24 patients with histologically proven pancreatic carcinoma were examined prospectively with a 64-slice dual source CT using a dynamic sequence of 34 dual-energy (DE) acquisitions every 1.5s (80 ml of iodinated contrast material, 370 mg/ml, flow rate 5 ml/s). 80 kV(p), 140 kV(p), and weighted average (linearly blended M0.3) 120 kV(p)-equivalent dual-energy perfusion image data sets were evaluated with a body-perfusion CT tool (Body-PCT, Siemens Medical Solutions, Erlangen, Germany) for estimating perfusion, permeability, and blood volume values. Color-coded parameter maps were generated. RESULTS: In all 24 patients dual-energy CT-perfusion was. All carcinomas could be identified in the color-coded perfusion maps. Calculated perfusion, permeability and blood volume values were significantly lower in pancreatic carcinomas compared to healthy pancreatic tissue. Weighted average 120 kV(p)-equivalent perfusion-, permeability- and blood volume-values determined from DE image data were 0.27 ± 0.04 min(-1) vs. 0.91 ± 0.04 min(-1) (p<0.0001), 0.5 ± 0.07 *0.5 min(-1) vs. 0.67 ± 0.05 *0.5 min(-1) (p=0.06) and 0.49 ± 0.07 min(-1) vs. 1.28 ± 0.11 min(-1) (p<0.0001). Compared with 80 and 140 kV(p) the standard deviations of the kV(p)120 kV(p)-equivalent values were manifestly smaller. CONCLUSION: Dual-energy CT-perfusion of the pancreas is feasible. The use of DECT improves the accuracy of CT-perfusion of the pancreas by fully exploiting the advantages of enhanced iodine contrast at 80 kV(p) in combination with the noise reduction at 140 kV(p). Therefore using dual-energy perfusion data could improve the delineation of pancreatic carcinomas.

[Diffusion-weighted imaging of the pancreas]. / Diffusionsbildgebung des Pankreas.

Diffusion-weighted imaging (DWI) has increasingly gained in importance over the last 10 years especially in cancer imaging for differentiation of malignant and benign lesions. Through development of fast magnetic resonance imaging (MRI) sequences DWI is not only applicable in neuroradiology but also in abdominal imaging. As a diagnostic tool of the pancreas DWI enables a differentiation between normal tissue, cancer and chronic pancreatitis. The ADC values (apparent diffusion coefficient, the so-called effective diffusion coefficient) reported in the literature for healthy pancreatic tissue are in the range from 1.49 to 1.9×10(-3) mm(2)/s, for pancreatic cancer in the range from 1.24 to 1.46×10(-3) mm(2)/s and for autoimmune pancreatitis an average ADC value of 1.012×10(-3) mm(2)/s. There are controversial data in the literature concerning the differentiation between chronic pancreatitis and pancreatic cancer. Using DWI-derived IVIM (intravoxel incoherent motion) the parameter f (perfusion fraction) seems to be advantageous but it is important to use several b values. In the literature the mean f value in chronic pancreatitis is around 16%, in pancreatic cancer 8% and in healthy pancreatic tissue around 25%. So far, DWI has not been helpful for differentiating cystic lesions of the pancreas. There are many references with other tumor entities and in animal models which indicate that there is a possible benefit of DWI in monitoring therapy of pancreatic cancer but so far no original work has been published.

Multidetector CT evaluation of the course of nonresectable pancreatic carcinomas with neoadjuvant therapy.

OBJECTIVE: A prospective study to determine the value of multidetector CT (MD-CT) in assessing the course of nonresectable pancreatic carcinoma during therapy. MATERIAL AND METHODS: 26 patients with nonresectable pancreatic carcinoma underwent MD-CT before and after therapy. The examinations were evaluated with regard to tumor size and vascular invasion using an invasion score (IS) by 2 radiologists independently (kappa analysis). Diagnosis was confirmed surgically, by biopsy or clinical course. RESULTS: Sensitivity for the assessment of irresectability was 100%. Following therapy, 54% of all the tumors were smaller (14/26), 42% had increased in volume (11/26), and one tumor remained stable (1/26). The IS (veins) during follow-up changed in 26 patients (portal vein: 5 higher (mean score 10.4/16.2), 4 lower (mean score 17.5/11.5); superior mesenteric vein: 12 higher (11/14.4), 5 lower (16.2/14.6); p = 0.026). The IS (arteries) changed in 13 patients (celiac trunk: 3 higher (3.3/10); hepatic artery: 4 higher (5.7/10.2), 3 lower (11.6/10.3); superior mesenteric artery: 2 higher (4.5/9.5), 1 lower (12/11)). The kappa values were calculated between 0.56 and 0.87. CONCLUSION: MD-CT is suitable for evaluating tumor spread during therapy for nonresectable pancreatic carcinoma. The IS is useful for assessing the degree of change in vessel invasion.

[Computed tomography of pancreatic tumors]. / Computertomographie bei Pankreastumoren.

Computed tomography (CT) and in particular multi-detector row computed tomography (MDCT), also known as multislice CT (MSCT), is ideally suited for detecting pancreatic tumors because of the high spatial resolution.The method of choice is hydro-CT which involves distension of the stomach and duodenum by administration of 1-1.5 l water as a negative contrast medium under medically induced hypotension by administration of buscopan. The patient is laid on the right side at an angle of 30-45 degrees in order to obtain an artefact-free image of the close anatomical relationship around the pancreas head. In addition, curved MPRs or in rare cases 3D reconstructions could be very helpful in identifying the critical anatomic tumor site in the neighbourhood of the visceral vessel system. After the correct diagnosis of an adenocarcinoma has been made only 20% of all patients are shown to have a surgically resectable disease, but the overall survival rate is significantly higher after resection in combination with a multimodal tumor therapy strategy. The reason is that the correct diagnosis of the resectability of the tumor is one of the main criteria for overall survival of these patients. Currently practically all pancreatic tumors can be detected using MDCT and the detection rate varies between 70% and 100% (most recent literature references give a sensitivity of 89% and specificity up to 99%). In some rare cases the differentiation between focal necrotizing pancreatitis and pancreatic carcinoma can be difficult even with sophisticated protocols. Resectability can be correctly diagnosed with MDCT with a sensitivity of 94% and a specificity of 89%. MDCT is an ideal tool for the detection of neuroendocrine tumors, metastases and for the differentiation of cystic pancreatic lesions such as pseudocysts, microcystic adenomas or intraductal papillary mucinous neoplasms (IPMN). Particularly, the differentiation of the latter into benign, borderline or malignant transformation is not always possible, but indirect signs, such as small nodules adjacent to the ductal wall, the diameter of the pancreatic duct, or a direct communication between cystic lesions and duct can be detected because of the high spatial resolution and is comparable to the findings in MRI. Moreover MD-CT is an ideal procedure for the differentiation of local tumor stages in patients under neoadjuvant or adjuvant chemotherapy.

A new invasion score for determining the resectability of pancreatic carcinomas with contrast-enhanced multidetector computed tomography.

OBJECTIVE: It was the aim of this study to evaluate a new infiltration score to determine the resectability of pancreatic carcinomas in preoperative planning. MATERIALS AND METHODS: Eighty patients with suspected pancreatic tumor were examined prospectively using 16-row spiral CT. The scans were evaluated for the presence of pancreatic carcinoma, peripancreatic tumor extension and vascular invasion using a standardized questionnaire. Invasion of the surgically relevant vessels was evaluated using a new invasion score. The operative and histological findings and the clinical follow-up served as the gold standard. RESULTS: Forty patients had a pancreatic carcinoma, 5 had metastasis of a different primary tumor, and in 35 patients, there was no malignant pancreatic disease. The sensitivity for tumor detection was 100%, with a specificity of 88% for differentiating between malignant and benign pancreatic tumors. Invasion of the surrounding vessels was evaluated correctly using the invasion score, with a sensitivity of 89% and a specificity of 99%. In evaluation of resectability, a sensitivity of 94% and a specificity of 89% were achieved. CONCLUSION: Using 16-row spiral CT, the invasion score is a valid tool for correctly assessing invasion in relevant vessels in cases of pancreatic carcinoma and for determining resectability.

[Diagnosis and staging of pancreatic carcinoma: MRI versus multislice-CT -- a prospective study]. / Hochauflösende Bildgebung beim Pankreaskarzinom: Prospektiver Vergleich von MRT und 4-Zeilen-Spiral-CT.

PURPOSE: To evaluate multislice-CT versus MRI in the diagnosis and staging of pancreatic carcinoma in a prospective multi-reader analysis. MATERIALS AND METHODS: Fifty patients with suspected pancreatic carcinoma underwent both multislice-CT (4-Row, "hydro-technique") and state-of-the-art MRI (two 1.5 T units). In correlation with histopathologic findings or in case of a non-lesion diagnosis by follow-up (6-month interval), we evaluated MRI versus CT in a multi-reader analysis (2 reader pairs) for: 1. diagnostic quality; 2. examination time; 3. accuracy of potential resectability; 4. kappa analysis of observer variations; and 5. overall diagnostic reliability. RESULTS: A total of 28 lesions (n = 22 malignant, n = 6 benign) were present in the cohort group versus 22 patients without a focal lesion (n = 10 pancreatitis, n = 12 no tumor). For lesion detection, CT had a sensitivity of 100/89 % (reader pair 1/2) and specificity of 77 %, and MRI had a sensitivity of 75/89 % and specificity of 77/73 %. For the subgroup of adenocarcinomas of the pancreas (n = 17), we found a sensitivity of 100 % and a specificity of 61 % for CT versus a sensitivity of 82/94 % and a specificity of 67/61 % for MRI. The accuracy for determining the resectability was 91/82 % for CT and 90/82 % for MRI. The kappa analysis showed a good correlation for CT (0.71) and a moderate correlation of both groups for MRI (0.49). CONCLUSION: CT and MRI showed comparable results in the detection of pancreatic carcinomas as well as in the determination of resectability. Chronic pancreatitis as a "tumor-like-lesion" was the major factor of a missed diagnosis. The results of multi-reader analysis for both reading groups were almost identical with a moderate to good kappa correlation. There is no reason to prefer MRI (more expensive) over CT for patients with the presumptive diagnosis of pancreatic cancer.