Dual-phase versus single-phase helical CT to detect and assess resectability of pancreatic carcinoma

Can a simplified CT response criteria for vascular involvement in pancreatic adenocarcinoma after neoadjuvant therapy predict survival in patients who achieved subsequent R0 resection?

PURPOSE

To investigate if a simplified image based scoring system assessing treatment response after neoadjuvant therapy (NAT) can predict survival in patients with pancreatic ductal adenocarcinoma (PDAC) who achieved subsequent R0 resection.

METHODS

Retrospective analysis of 57 PDAC patients (male = 29, 51%) with mean age of 64 at diagnosis (range 42-79) who received NAT and R0 resection. Post-NAT overall, arterial and venous imaging response was characterized as improved, similar, or worse by 2 readers independently followed by consensus review. Kaplan-Meier Analysis was performed to compare overall survival (OS) with post-NAT overall imaging response. A Multivariable Cox proportional hazards analysis was performed to evaluate the association of the following variables with OS: overall, arterial and venous radiology response, clinical staging, postoperative CA19-9, and patient age.

RESULTS

At study conclusion, 30/57 patients were deceased (53%), 26/57 (46%) alive, and 1 patient unknown. Post-NAT, 39/57 (68.4%) had overall improved disease and 18/57 (31.6%) had similar disease. The median OS was 55.7 months (95% CI 33.4-not reached, NR) for those with improved disease vs. 53.9 months (95% CI 14.3-NR) with similar disease (p = 0.859) after NAT. Among all clinical parameters, only post-operative CA 19-9 level was associated with OS (p = 0.002) and PFS (p = 0.005), respectively.

CONCLUSION

Pancreatic cancer patients who underwent R0 resection showed no difference in survival when comparing those with similar vs improved disease on post-NAT imaging.

Use of imaging as staging and surgical planning for pancreatic surgery

Importance

In the past few decades, there has been rapid advancements in imaging technologies that have become irreplaceable in the pre-operative assessment of patients with pancreatic tumors. Modern imaging modalities, including computed tomography (CT) and endoscopic ultrasound (EUS), can provide critical information of the absence or presence of metastatic disease in pancreatic cancer, as well as details on the local extent and resectability, allowing for the selection of stage appropriate treatments and pre-operatively determined surgical approach.

Objective

The aim of this review is to discuss staging, resectability, and imaging for patients with pancreatic tumors.

Evidence Review

A literature review was performed of articles relevant to the topics of staging, resectability, and imaging of pancreatic tumors. Imaging modalities included CT, EUS, magnetic resonance imaging (MRI), positron emission tomography (PET), antibody-based and narrow band imaging.

Findings

CT pancreas protocol combined with EUS serve as the primary modalities in diagnosis, staging, and surgical planning in patients with pancreatic tumors. MRI is an alternative to CT with near equivalent utility in the pre-operative setting. In some circumstances, PET-CT may be a cost-effective initial study to detect distant disease.

Conclusions and Relevance

Current imaging technologies play a critical role in the evaluation of patients with pancreatic tumors. Advances in the past 3 decades in imaging technologies have revolutionized the process of assessment of stage and resectability in patients with pancreatic tumors. Future imaging technologies will address current limitation in the evaluation of occult metastatic disease.

Intravoxel incoherent motion MRI for the differentiation between mass forming chronic pancreatitis and pancreatic carcinoma

PURPOSE

To determine which of the quantitative parameters obtained from intravoxel incoherent motion diffusion weighted imaging (DWI) is the most significant for the differentiation between pancreatic carcinoma and mass-forming chronic pancreatitis.

MATERIALS AND METHODS

Twenty-nine patients with pancreatic masses were included, 9 proved to have a mass-forming pancreatitis and 20 had a pancreatic carcinoma. The patients were studied using intravoxel incoherent motion DWI with 11 b-values and the apparent diffusion coefficient (ADC), the true diffusion constant (D) and the perfusion fraction (f) were calculated. The diagnostic strength of the parameters was evaluated using receiver operating characteristic analysis.

RESULTS

The ADC in chronic pancreatitis was higher than in pancreatic carcinoma with significant differences at b = 50, 75, 100, 150, 200, 300 s/mm (ADC50 = 3.17 ± 0.67 vs. 2.55 ± 1.09, ADC75 = 2.46 ± 0.4 vs. 1.93 ± 0.52, ADC100 = 2.28 ± 0.48 vs. 1.73 ± 0.45, ADC150 = 1.97 ± 0.26 vs. 1.63 ± 0.40, ADC200 = 1.98 ± 0.24 vs. 1.53 ± 0.28, and ADC300 = 1.76 ± 0.19 vs. 1.46 ± 0.31 × 10(-3) mm2/s). No significant differences were found at b = 25, 400, 600, and 800 s/mm (ADC25 = 4.69 ± 0.65 vs. 4.04 ± 1.35, ADC400 = 1.57 ± 0.21 vs. 1.37 ± 0.30, ADC600 = 1.38 ± 0.18 vs. 1.24 ± 0.25, and ADC800 = 1.27 ± 0.10 vs. 1.18 ± 0.19 × 10(-3) mm2/s) nor using ADCtot (1.42 ± 0.23 vs. 1.28 ± 0.12 × 10(-3) mm2/s). The perfusion fraction f was significantly higher in pancreatitis compared with pancreatic carcinoma (16.3% ± 5.30% vs. 8.2% ± 4.00%, P = 0.0001). There was no significant difference between groups for D (1.07 ± 0.224 × 10(-3) mm2/s for chronic pancreatitis and 1.09 ± 0.3 × 10(-3) mm2/s for pancreatic carcinoma, P = 0.66). For f, the highest area under the curve (0.894) and combined sensitivity (80%) and specificity (89.9%) were found.

CONCLUSIONS

There were significant differences in ADC50-300 between chronic pancreatitis and pancreatic carcinoma. Because D is not significantly different between groups, differences in ADC can be attributed mainly to differences in perfusion. The perfusion fraction f proved to be the superior DWI-derived parameter for differentiation of mass-forming pancreatitis and pancreatic carcinoma.

Vascular invasion in pancreatic cancer: Imaging modalities, preoperative diagnosis and surgical management

Pancreatic cancer is associated with a poor prognosis, and surgical resection remains the only chance for curative therapy. In the absence of metastatic disease, which would preclude resection, assessment of vascular invasion is an important parameter for determining resectability of pancreatic cancer. A frequent error is to misdiagnose an involved major vessel. Obviously, surgical exploration with pathological examination remains the “gold standard” in terms of evaluation of resectability, especially from the point of view of vascular involvement. However, current imaging modalities have improved and allow detection of vascular invasion with more accuracy. A venous resection in pancreatic cancer is a feasible technique and relatively reliable. Nevertheless, a survival benefit is not achieved by curative resection in patients with pancreatic cancer and vascular invasion. Although the discovery of an arterial invasion during the operation might require an aggressive management, discovery before the operation should be considered as a contraindication. Detection of vascular invasion remains one of the most important challenges in pancreatic surgery. The aim of this article is to provide a complete review of the different imaging modalities in the detection of vascular invasion in pancreatic cancer.

Comparison between multislice CT and MR imaging in the diagnostic evaluation of patients with pancreatic masses

PURPOSE

This study compared the results of multislice computed tomography (MSCT) and high-field magnetic resonance imaging (MRI) in the diagnostic evaluation of pancreatic masses.

MATERIALS AND METHODS

Forty patients with clinical and ultrasonographic evidence of pancreatic masses underwent MSCT and MRI. The majority of patients (31/40, 78%) had proven malignant pancreatic tumours (24 ductal adenocarcinoma, six mucinous cystadenocarcinoma, one intraductal papillary mucinous carcinoma), whereas the remaining patients (9/40, 22%) were found to have benign lesions (eight chronic pancreatitis, one serous cystadenoma). Results of the imaging studies were compared with biopsy (n=33) and/or histology (n=7) findings to calculate sensitivity, specificity, accuracy and positive (PPV) and negative (NPV) predictive value for correct identification of tumours and evaluation of resectability of malignancies.

RESULTS

Both for tumour identification and resectability, MSCT and MRI had comparable diagnostic accuracy, with no statistically significant differences between them. Tumour identification CT/MRI: accuracy 98/98%, sensitivity 100/100%, specificity 88/88%, PPV 97/97%, NPV 100/100%; tumour resectability CT/MRI: accuracy 94/90%, sensitivity 92/88%, specificity 100/100%, PPV 100/100%, NPV 78/70%.

CONCLUSIONS

MRI represents a valid diagnostic alternative to CT in the evaluation of patients with pancreatic masses, both for correct identification and characterisation of primary lesions and to establish resectability in the case of malignancies. New high-field MRI equipment allows optimal imaging quality with good contrast resolution in evaluating the upper abdomen.

MDCT of the pancreas: optimizing scanning delay with a bolus-tracking technique for pancreatic, peripancreatic vascular, and hepatic contrast enhancement

OBJECTIVE

The purpose of this study was to determine the optimal MDCT scanning delay for peripancreatic arterial, pancreatic parenchymal, peripancreatic venous, and hepatic parenchymal contrast enhancement with a bolus-tracking technique.

SUBJECTS AND METHODS

Three-phase 8-MDCT of the pancreas was performed on 170 patients after administration of 2 mL/kg of 300 mg I/mL contrast medium injected at 4 mL/s to a total dose of 150 mL. Patients were prospectively randomized into three groups with different scanning delays for the three phases (arterial, pancreatic, and venous) after bolus tracking was triggered at 50 H of aortic contrast enhancement: group 1 (5, 20, 45 seconds); group 2 (10, 25, 50 seconds); and group 3 (15, 30, 55 seconds). Mean attenuation values of the abdominal aorta, superior mesenteric artery, pancreatic parenchyma, splenic vein, superior mesenteric vein, portal vein, and hepatic parenchyma were measured. Increases in attenuation values after contrast administration were assessed as change in attenuation value. Qualitative analysis also was performed.

RESULTS

Mean contrast enhancement in the aorta (change in attenuation, 321-327 H) and the superior mesenteric artery (change in attenuation, 304-307 H) approached peak enhancement 5-10 seconds after bolus tracking was triggered. Pancreatic parenchyma became most intensely enhanced (change in attenuation, 84-85 H) 15-20 seconds after triggering, and then the enhancement gradually decreased. Enhancement of the splenic vein and portal vein peaked 25 seconds and that of the superior mesenteric vein peaked 30 seconds after triggering. Liver parenchyma reached 52 H 30 seconds after triggering and reached a plateau (change in attenuation, 58-61 H) at a further scanning delay of 45-55 seconds. Qualitative results were in good agreement with quantitative results.

CONCLUSION

For the injection protocol used in this study, optimal scanning delay after triggering of bolus tracking at 50 H of aortic contrast enhancement was 5-10 seconds for the peripancreatic arterial phase, 15-20 seconds for the pancreatic parenchymal phase, and 45-55 seconds for the hepatic parenchymal phase.

Evaluation of vascular infiltration in resected patients for pancreatic cancer: comparison among multidetector CT, intraoperative findings and histopathology

BACKGROUND

To assess vascular infiltration is crucial in surgical planning of pancreatic cancer. Our aim was to assess the capability of multidetector CT in detecting vascular infiltration.

METHODS

We evaluated 37 patients with pancreatic tumors. The relation between tumor and vessels was classified: grade 0: no contact between lesion and vessel; grade I: focal contiguity without modification of the vessel caliber; grade II: lesion surrounding the vessel, without reduction of its lumen; grade III: cancer surrounding the vessel with reduction or obstruction of its lumen. CT grades were compared to intraoperative findings and histopathology.

RESULTS

We evaluated 52 critical vessels with the following CT grades: grade 0 (4 cases), grade I (13 cases), grade II (17 cases), grade III (18 cases). Vascular resection was performed in 26 patients, with a total of 31 resected vessels (3 of grade 0, 5 of grade I, 8 of grade II, 15 of grade III). Histopathology excluded vascular infiltration in 4/4 cases with grade 0 and in 10/13 cases with grade I and confirmed it in 14/17 cases with grade II and 14/18 cases with grade III.

CONCLUSIONS

Multidetector CT is accurate in detecting vascular involvement and provides pre-operative information to effectively plan resection.

Pancreatic adenocarcinoma: MDCT versus MRI in the detection and assessment of locoregional extension

PURPOSE

To compare dynamic-contrast enhanced multirow detector computed tomography (MDCT) including multiplanar reformatted images (MPR) and magnetic resonance imaging (MRI) including magnetic resonance cholangiopancreatography images for the detection and assessment of locoregional extension of pancreatic adenocarcinoma.

MATERIALS AND METHODS

Twenty-four patients with and 21 patients without pancreatic adenocarcinoma underwent triple-phase MDCT and MRI. Three radiologists independently attempted to detect pancreatic adenocarcinoma and assess locoregional extension in 3 sessions. First session involved MDCT images. In the second session, radiologists had access to coronal and sagittal MPR images together with the axial images (MDCT + MPR). Third session involved MR images. Results were compared with surgical findings using receiver operating characteristic analysis and kappa statistics.

RESULTS

Regarding tumor detection, MDCT + MPR had a significantly higher value for areas under the curve (0.96 +/- 0.02) at receiver operating characteristic analysis compared with those of MRI (0.90 +/- 0.03) and MDCT (0.85 +/- 0.04). MDCT + MPR had the highest mean sensitivity (96%), and MRI had the highest mean specificity (98%). For locoregional extension, MDCT + MPR showed the highest kappa values of the study for all factors evaluated (range, 0.63-0.86).

CONCLUSIONS

In conclusion, multiphasic MDCT imaging with MPR images was superior to multiphasic MDCT imaging without MPR images and to comprehensive MRI employing 2-D sequences and magnetic resonance cholangiopancreatography for both the detection and assessment of locoregional extension of pancreatic adenocarcinomas. MRI might be used for further lesion characterization regarding its high specificity.

The inherited genetics of pancreatic cancer and prospects for secondary screening

It is estimated that pancreatic cancer has a familial component in approximately 5-10% of cases. Some of these cases are part of a defined cancer syndrome with a known gene mutation but in the remaining the causative gene remains unknown. In recent years, a better understanding of the molecular events that occur in the progression model of pancreatic cancer has lead to the development of secondary screening programmes with the aim of identifying early precursor lesions or pre-invasive cancer at a stage amenable to curative resection. High-risk groups who have an inherited predisposition for pancreatic cancer form the ideal group to study in developing a robust screening programme. Multimodality screening using computed tomography and endoluminal ultrasound in combination with molecular analysis of pancreatic juice are proving promising as diagnostics tools or at least serving as predictors of risk over a defined period.

Pancreatic head cancer: accuracy of CT in determination of resectability

BACKGROUND

Pancreatic cancer is a devastating disease whose early detection remains difficult. There is no 100% reliable imaging test to diagnose and stage pancreatic cancer. We assessed the surgical value of contrast-enhanced spiral computed tomography (CT) in predicting the resectability and survival rates of patients who had pancreatic head cancer.

METHODS

Eighty-nine patients who had pancreatic head cancer were investigated with spiral CT. Based on the preoperative CT results, we assigned patients to one of three CT groups based on resectability.

RESULTS

A correlation between classification of CT resectability and intraoperative finding was found in 83% of patients. The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of spiral CT in identifying predictive unresectability were 79%, 82%, 91%, 62%, and 81%, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT in diagnosis of vascular invasion were 94%, 84.2%, 94%, 84%, and 91.3%, respectively.

CONCLUSION

The use of CT in the evaluation of pancreatic tumors provides valuable preoperative assessment of surgical resectability and should be performed for clinical examination. Classifying patients by tumor resectability on CT helps to estimate more precisely the tumor stage and to prognosticate survival rates of these patients.

Ultrasonography, computed tomography and magnetic resonance imaging for diagnosis and determining resectability of pancreatic adenocarcinoma: a meta-analysis

OBJECTIVE

To compare ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) in the diagnosis and determination of resectability of pancreatic adenocarcinoma.

METHODS

Articles reporting US, CT, or MRI data of patients with known or suspected pancreatic adenocarcinoma and at least 20 patients verified with histopathology, surgical findings, or follow-up were included. A bivariate random effects approach was used to calculate sensitivity and specificity for diagnosis and resectability of pancreatic adenocarcinoma.

RESULTS

Sixty-eight articles fulfilled all inclusion criteria. For diagnosis, sensitivities of helical CT, conventional CT, MRI, and US were 91%, 86%, 84%, and 76% and specificities were 85%, 79%, 82%, and 75% respectively. Sensitivities for MRI and US were significantly lower compared with helical CT (P = 0.04 and P = 0.0001). For determining resectability, sensitivities of helical CT, conventional CT, MRI, and US were 81%, 82%, 82, and 83% and specificities were 82%, 76%, 78%, and 63% respectively. Specificity of US was significantly lower compared with helical CT (P = 0.011).

CONCLUSIONS

Helical CT is preferable as an imaging modality for the diagnosis and determination of resectability of pancreatic adenocarcinoma.

Value of the single-phase technique in MDCT assessment of pancreatic tumors

OBJECTIVE

The purpose of our study was to determine the diagnostic value of single-phase MDCT in patients with suspected pancreatic carcinoma.

SUBJECTS AND METHODS

Seventy-one patients (41 men, 30 women; mean age, 63 years; range, 29-80 years) with suspected pancreatic tumor underwent MDCT. Scanning was performed on an MDCT scanner with 0.5-sec gantry rotation and acquisition of 4 slices per rotation. Unenhanced scanning was followed by one set of scanning in the caudocranial direction from the inferior hepatic margin to the diaphragm with a scanning delay of 60 sec after the IV injection of 150 mL of contrast material delivered at 3 mL/sec. Two reviewers independently scored images in a blinded fashion for the presence of tumor and assessment of resectability. Receiver operating characteristic analysis was performed.

RESULTS

A final histopathologic diagnosis derived from surgical findings was obtained in 42 patients; in the remaining 29 patients, percutaneous fine-needle aspiration biopsy coupled with a 1-year clinical follow-up to determine development of local, regional or distant neoplasm served as gold standard proof of diagnosis. Final diagnosis was pancreatic cancer in 40 patients (27 ductal adenocarcinoma, nine mucinous cystoadenocarcinoma, two neuroendocrine tumors, one lymphoma, and one papillary cystoadenocarcinoma) and chronic pancreatitis in 31. The mean tumor size was 2.4 cm (range, 4-1 cm). Values for the area under the curve (A(z)) for the assessment of tumor detection were 0.97 for reviewer 1 and 0.96 for reviewer 2 (p = not significant). A(z) values for tumor resectability were 0.90 for reviewer 1 and 0.90 for reviewer 2 (p = not significant). No statistically significant differences were observed between superior mesenteric artery and vein opacification with the hepatic parenchyma enhanced at a time closer to the peak hepatic enhancement, optimizing the detection of hepatic lesions.

CONCLUSION

Thin-section single-phase MDCT is an accurate technique for the diagnosis and assessment of resectability in patients with a suspected pancreatic neoplasm. This technique provides optimal tumor-to-pancreas contrast and maximal pancreatic parenchymal and peripancreatic vascular enhancement. It allows visualization of the entire liver and the whole upper abdomen during the portal phase for accurate identification of liver metastases and peritoneal seeding.

Time interval between abnormalities seen on CT and the clinical diagnosis of pancreatic cancer: retrospective review of CT scans obtained before diagnosis

OBJECTIVE

Our purpose was to determine whether abdominal CT can detect pancreatic cancer before its clinical diagnosis.

SUBJECTS AND METHODS

Two radiologists interpreted in a blinded manner 62 CT scans in 28 pancreatic cancer patients that were obtained before histologic diagnosis and 89 CT scans in 89 control subjects and noted specific CT findings. The presence of pancreatic cancer was characterized as definite, suspicious, low probability, or normal. The scans of the pancreatic cancer patients were divided into four groups on the basis of the time interval preceding cancer diagnosis (0-2, 2-6, 6-18, or > 18 months), and one scan (closest to 18 months) was selected per patient per time interval. Sensitivity and specificity for pancreatic cancer and interobserver agreement for CT findings were calculated.

RESULTS

Radiologists agreed that CT findings definite or suspicious for pancreatic cancer were present in 50% of the scans obtained 2-6 and 6-18 months before the diagnosis of pancreatic cancer (3/6 and 4/8 scans, respectively), but they noted such CT findings in only 7% (1/15) of the scans obtained more than 18 months before diagnosis. Pancreatic duct dilatation and cutoff were early CT findings identified by both radiologists and were associated with near-perfect and substantial interobserver agreement (kappa = 0.84 and 0.76, respectively). Ninety-five percent confidence intervals of specificity for tumor absence ranged from 92% to 100%.

CONCLUSION

CT can detect a significant proportion of asymptomatic incident pancreatic cancers before the clinical diagnosis of pancreatic cancer. CT should be considered in screening at-risk patient populations. Pancreatic duct dilatation and cutoff are early findings associated with the development of pancreatic cancer and can be detected on CT with a high degree of reproducibility.

Radial endoscopic ultrasound and spiral computed tomography in the diagnosis and staging of periampullary tumors

BACKGROUND AND STUDY AIMS

The early detection and accurate staging of pancreatic and ampullary cancer is of utmost importance for the achievement of surgical radical treatment. The aim of this study was to assess prospectively the role of endoscopic ultrasonography (EUS) in detection and staging of pancreatic and ampullary cancer, comparing its results to those obtained with spiral computed tomography (SCT).

PATIENTS AND METHODS

Sixty-one patients with suspected pancreatic and ampullary tumors were included, 46 (75, 4%) of whom presented with obstructive jaundice. Patients underwent EUS and SCT within a 7-day period. Examiners were unaware of the previous imaging results, except conventional echography. Image interpretation was compared to surgical and histopathological findings.

RESULTS

Fifty-six (91, 8%) patients were surgically explored. Clinical follow-up and/or tissue diagnosis determined the correct diagnosis in the remaining five patients. Pancreatic cancer and ampullary cancer were observed in 29 (47, 6%) and 10 (16, 4%) patients, respectively. Chronic pancreatitis and choledocholithiasis were the most common diagnosis in patients with non-neoplastic disease. EUS was more effective than SCT for the definition of the final diagnosis in patients with obstructive jaundice (87.0 vs. 67.4%, p = 0.04). Both exams were equally effective for detecting pancreatic cancer but EUS predicted more accurately the involvement of portal-mesenteric axis by the tumor (87.0 vs. 67.4%, p = 0.04). EUS was particularly useful in the diagnosis of cancer of papilla of Vater.

CONCLUSION

In patients with pancreatic adenocarcinoma without unequivocal signs of distant metastatic disease, EUS is more accurate than SCT to predict venous involvement by the tumor. EUS is superior to SCT to detect ampullary adenocarcinoma. Both methods are equally ineffective to detect nodal involvement in pancreatic and ampullary cancer.

Impact of multislice CT on imaging of acute abdominal disease

The increased speed, greater coverage, and thinner slices of MSCT are exciting developments in radiology, and these feature should only improve with newer generation multislice scanners. The impact of this technology on abdominal imaging has just begun.

Peripancreatic masses that simulate pancreatic disease: spectrum of disease and role of CT

A number of entities can simulate pancreatic disease at computed tomography (CT), which may lead to misdiagnosis. Common pitfalls include peripancreatic lesions of the foregut, adrenal gland, and kidney as well as disease of the mesentery and neurovascular structures. Optimal design and application of multi-detector row CT protocols with multiplanar reformation and maximum-intensity-projection and volume-rendering postprocessing improves the specificity of image interpretation. In most cases, helical CT is highly accurate for distinguishing primary disease of the pancreas from adjacent disease, although there are cases in which the differential diagnosis is more challenging and the potential for misdiagnosis still exists. Familiarity with some of the entities that can simulate pancreatic disease, careful attention to scanning protocol and contrast material administration, use of the full potential of multi-detector row CT data sets, and judicious application of postprocessing tools may help avoid some of the pitfalls caused by peripancreatic lesions.