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

Contrast-enhanced CT in determining resectability in patients with pancreatic carcinoma: a meta-analysis of the positive predictive values of CT

OBJECTIVE

To obtain a summary positive predictive value (sPPV) of contrast-enhanced CT in determining resectability.

METHODS

The MEDLINE and EMBASE databases from JAN2005 to DEC2015 were searched and checked for inclusion criteria. Data on study design, patient characteristics, imaging techniques, image evaluation, reference standard, time interval between CT and reference standard, and data on resectability/unresectablity were extracted by two reviewers. We used a fixed-effects or random-effects approach to obtain sPPV for resectability. Several subgroups were defined: 1) bolus-triggering versus fixed-timing; 2) pancreatic and portal phases versus portal phase alone; 3) all criteria (liver metastases/lymphnode involvement/local advanced/vascular invasion) versus only vascular invasion as criteria for unresectability.

RESULTS

Twenty-nine articles were included (2171 patients). Most studies were performed in multicentre settings, initiated by the department of radiology and retrospectively performed. The I2-value was 68%, indicating heterogeneity of data. The sPPV was 81% (95%CI: 75-86%). False positives were mostly liver, peritoneal, or lymphnode metastases. Bolus-triggering had a slightly higher sPPV compared to fixed-timing, 87% (95%CI: 81-91%) versus 78% (95%CI: 66-86%) (p = 0.077). No differences were observed in other subgroups.

CONCLUSIONS

This meta-analysis showed a sPPV of 81% for predicting resectability by CT, meaning that 19% of patients falsely undergo surgical exploration.

KEY POINTS

• Predicting resectability of pancreatic cancer by CT is 81% (95%CI: 75-86%). • The percentage of patients falsely undergoing surgical exploration is 19%. • The false positives are liver metastases, peritoneal metastases, or lymph node metastases.

The diagnostic pathway for solid pancreatic neoplasms: are we applying too many tests?

BACKGROUND

The single best diagnostic and staging test for pancreatic cancer remains a contrast-enhanced computed tomography scan. It is frequently the only imaging test required before surgical resection for solid pancreatic lesions. Unfortunately, many patients undergo additional testing that often delays definitive care.

MATERIALS AND METHODS

A retrospective review of all patients with solid pancreatic lesions concerning for adenocarcinoma referred to a high volume Hepato-Pancreato-Biliary (HPB) service over 4 y (2008-2012) was completed. The time intervals between the initial imaging test and both consultation with HPB surgery and operative intervention, as well as the number of additional tests, were evaluated. Standard statistical methodology was used (P < 0.05).

RESULTS

Among 130 patients with solid pancreatic lesions, the index imaging modality was ultrasonography and computed tomography for 75 (58%) and 52 (40%), respectively. Patients underwent a mean of 1.3 diagnostic tests after the index study and before consultation with HPB surgery (range: 0-5). There was a significant increase in time to HPB consultation and operative intervention with an increasing number of interval imaging tests. The mean time to surgical consultation and operation if 0 interval diagnostic tests were performed was 15.9 and 45.4 d, respectively. If four interval tests were conducted, the mean was 69.4 and 122.6 d, respectively. Sixty-two patients (48%) were initially referred to a nonsurgical service. The mean time to surgical consultation and operation if an intervening referral occurred was 36.6 and 66.8 d, respectively. This compares to 19.8 and 48.1 d, respectively, in cases of direct referral to an HPB surgeon. The mean number of diagnostic tests performed before HPB consultation if a nonsurgical referral occurred was 2.1 (versus 0.7 if direct HPB surgeon referral).

CONCLUSIONS

Despite a relatively simple algorithm for the investigation of solid pancreatic lesions, considerable heterogeneity remains in how these patients are evaluated before referral to HPB surgery. As the number of investigations increases after the index imaging test, there is increasing delay to both surgical consultation and definitive intervention. Education is required to expedite care and mitigate excess diagnostic tests.

When the non-contrast-enhanced phase is unnecessary in abdominal computed tomography scans? A retrospective analysis of 244 cases

Objective: To evaluate the necessity of the non contrast-enhanced phase in abdominal computed tomography scans. Materials and Methods: A retrospective, cross-sectional, observational study was developed, evaluating 244 consecutive abdominal computed tomography scans both with and without contrast injection. Initially, the contrast-enhanced images were analyzed (first analysis). Subsequently, the observers had access to the non-contrast-enhanced images for a second analysis. The primary and secondary diagnoses were established as a function of the clinical indications for each study (such as tumor staging, acute abdomen, investigation for abdominal collection and hepatocellular carcinoma, among others). Finally, the changes in the diagnoses resulting from the addition of the non-contrast-enhanced phase were evaluated. Results: Only one (0.4%; p > 0.999; non-statistically significant) out of the 244 reviewed cases had the diagnosis changed after the reading of non-contrast-enhanced images. As the secondary diagnoses are considered, 35 (14%) cases presented changes after the second analysis, as follows: nephrolithiasis (10%), steatosis (3%), adrenal nodule (0.7%) and cholelithiasis (0.3%). Conclusion: For the clinical indications of tumor staging, acute abdomen, investigation of abdominal collections and hepatocellular carcinoma, the non-contrast-enhanced phase can be excluded from abdominal computed tomography studies with no significant impact on the diagnosis.

Quando a fase de equilíbrio pode ser suprimida nos exames de tomografia computadorizada de abdome?

OBJETIVO: Avaliar a necessidade de realização da fase de equilíbrio nos exames de tomografia computadorizada de abdome. MATERIAIS E MÉTODOS: Realizou-se estudo retrospectivo, transversal e observacional, avaliando 219 exames consecutivos de tomografia computadorizada de abdome com contraste intravenoso, realizados num período de três meses, com diversas indicações clínicas. Para cada exame foram emitidos dois pareceres, um avaliando o exame sem a fase de equilíbrio (primeira análise) e o outro avaliando todas as fases em conjunto (segunda análise). Ao final de cada avaliação, foi estabelecido se houve mudança nos diagnósticos principais e secundários, entre a primeira e a segunda análise. Foi utilizada a extensão do teste exato de Fisher para avaliar a modificação dos diagnósticos principais (p < 0,05 como significante). RESULTADOS: Entre os 219 casos avaliados, a supressão da fase de equilíbrio provocou alteração no diagnóstico principal em apenas um exame (0,46%; p > 0,999). Com relação aos diagnósticos secundários, cinco exames (2,3%) foram modificados. CONCLUSÃO: Para indicações clínicas como estadiamento tumoral, abdome agudo e pesquisa de coleção abdominal, a fase de equilíbrio não acrescenta contribuição diagnóstica expressiva, podendo ser suprimida dos protocolos de exame.

Multimodality imaging of pancreatic ductal adenocarcinoma: a review of the literature

BACKGROUND

Accurate pre-operative imaging in pancreatic cancer helps avoid unsuccessful surgical explorations and forewarns surgeons regarding aberrant anatomy. This review aimed to determine the role of current imaging modalities in the diagnosis and determination of resectability of pancreatic and peri-ampullary adenocarcinomas.

METHODS

A systematic search of the scientific literature was carried out using EMBASE, PubMed/MEDLINE and the Cochrane Central Register of Controlled Trials for the years 1990 to 2011 to obtain access to all publications, especially randomized controlled trials, reporting on the diagnostic accuracy of ultrasonography, multi-detector computed tomography (MDCT), magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) or positron emission tomography (PET)-computed tomography (CT) and the evaluation of resectability of pancreatic and peri-ampullary adenocarcinomas.

RESULTS

Based on 66 articles analysed in the review, MDCT and MRI/MRCP have comparable sensitivity and specificity rates for diagnosis and staging of pancreatic cancers. EUS offers the best sensitivity and specificity rates for lesions <2 cm. Improved staging has been noted when PET-CT scans are added to pre-operative evaluation.

CONCLUSIONS

MDCT with angiography or MRI/MRCP should constitute the first imaging modality in suspected pancreatic adenocarcinomas. EUS is recommended for assessing lesions not clearly detected, but suspected, on CT/MRI and in tumours considered 'borderline resectable' on MDCT to assess vascular involvement. PET-CT in locally advanced lesions will help rule out distant metastases.

Characterization of small solid tumors in the pancreas: the value of contrast-enhanced harmonic endoscopic ultrasonography

OBJECTIVES

Contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS), a novel technology, visualizes parenchymal perfusion in the pancreas. This study prospectively evaluated how accurately CH-EUS characterizes pancreatic lesions and compared its diagnostic ability with that of contrast-enhanced multidetector-row computed tomography (MDCT) and endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA).

METHODS

A total of 277 consecutive patients with pancreatic solid lesions that were detected by conventional EUS underwent CH-EUS for evaluation of vascularity. After infusing an ultrasound contrast, CH-EUS was performed by using an echoendoscope and a specific mode for contrast harmonic imaging. On the basis of the intensity of enhancement, the lesions were categorized into four patterns: nonenhancement, hypoenhancement, isoenhancement, and hyperenhancement. For comparison, all patients underwent MDCT. The ability of CH-EUS to differentiate ductal carcinomas from the other solid tumors, particularly small lesions (≤2 cm in diameter) was assessed, and compared with the differentiating abilities of MDCT and EUS-FNA.

RESULTS

In terms of reading the CH-EUS images, the κ-coefficient of the interobserver agreement test was 0.94 (P<0.001). CH-EUS-depicted hypoenhancement diagnosed ductal carcinomas with a sensitivity and specificity of 95.1% (95% confidence interval (CI) 92.7-96.7%) and 89.0% (95% CI 83.0-93.1%), respectively. For diagnosing small carcinomas by CH-EUS, the sensitivity and specificity were 91.2 % (95% CI 82.5-95.1%) and 94.4% (95% CI 86.2-98.1%), respectively. CH-EUS-depicted hypervascular enhancement diagnosed neuroendocrine tumors with a sensitivity and specificity of 78.9% (95% CI 61.4-89.7%) and 98.7% (95% CI 96.7-98.8%), respectively. Although CH-EUS and MDCT did not differ significantly in diagnostic ability with regard to all lesions, CH-EUS was superior to MDCT in diagnosing small (≤2 cm) carcinomas (P<0.05). In 12 neoplasms that MDCT failed to detect, 7 ductal carcinomas and 2 neuroendocrine tumors had hypoenhancement and hyperenhancement on CH-EUS, respectively. When CH-EUS was combined with EUS-FNA, the sensitivity of EUS-FNA increased from 92.2 to 100%.

CONCLUSIONS

CH-EUS is useful for characterizing conventional EUS-detected solid pancreatic lesions. EUS equipped with contrast harmonic imaging may play an important role in the characterization of small tumors that other imaging methods fail to depict and may improve the diagnostic yield of EUS-FNA.

Contrast-enhanced sonography of nonfunctioning pancreatic neuroendocrine tumors

OBJECTIVE

Diagnosis of malignancy and prognostic assessment continue to be problems in the management of nonfunctioning pancreatic endocrine tumors. Histologic examination is the reference standard. The aim of our study was to compare B-mode and contrast-enhanced sonographic findings regarding nonfunctioning pancreatic endocrine tumors. Signs of malignancy, such as Ki67 index and presence of hepatic metastasis, were considered.

MATERIALS AND METHODS

We retrospectively reviewed the cases of 38 consecutively registered patients with nonfunctioning pancreatic endocrine tumors evaluated with B-mode and contrast-enhanced sonography and resected. At contrast-enhanced sonography all lesions were divided into hypovascular lesions and isovascular or hypervascular lesions. On the basis of homogeneity of enhancement, lesions were classified as homogeneous and inhomogeneous. During the late phase of contrast enhancement, all solid focal hypoechoic liver lesions detected at contrast-enhanced sonography were considered hepatic metastatic lesions. Among pathologic data, grading, mitotic index, and Ki67 index were evaluated. Spearman's test was used to compare contrast-enhanced sonographic enhancement pattern with pathologic grade.

RESULTS

In the arterial phase, 24 of 38 nonfunctioning pancreatic endocrine tumors (63.1%) were hypervascular, seven (18.4%) were isovascular, and seven (18.4%) were hypovascular. Positive correlation was found between contrast-enhanced sonographic findings and Ki67 index (r(s) = 0.62; p < 0.0001). The difference between contrast-enhanced and B-mode sonography in the diagnosis of nonfunctioning pancreatic endocrine tumors was statistically significant (p < 0.05). Use of contrast-enhanced sonography increased diagnostic confidence in the detection of hepatic metastasis. The areas under the receiver operating characteristic curves were 0.916 for B-mode sonography and 1.000 for contrast-enhanced sonography (p < 0.05). There was moderate positive correlation between contrast-enhanced sonographic enhancement pattern and the presence of hepatic metastasis at diagnosis (r(s) = 0.46; p = 0.004) and between Ki67 index and the presence of hepatic metastasis (r(s) = 0.48; p = 0.0022).

CONCLUSION

The contrast-enhanced sonographic enhancement pattern of nonfunctioning pancreatic endocrine tumors has a positive correlation with Ki67 index, which is considered the most reliable independent predictor of the presence of malignancy.

Retrospective analysis of dual-phase MDCT and follow-up EUS/EUS-FNA in the diagnosis of pancreatic cancer

BACKGROUND

The optimal approach for detecting small pancreatic tumors is uncertain. We compared multidetector CT (MDCT) with follow-up endoscopic ultrasonography (EUS) without or with fine-needle aspiration (EUS-FNA) for diagnosing pancreatic cancer.

METHODS

Patients with suspicion of pancreatic cancer who underwent dual-phase MDCT and follow-up EUS were retrospectively reviewed. This consisted of scoring MDCT scans independently by three radiologists on a 1-5 scale of certainty, determining whether a stent was present, scoring EUS reports regarding presence of a mass and analyzing EUS-FNA results.

RESULTS

A total of 117 patients underwent MDCT and EUS. ROC values for MDCT were 0.85, 0.87, and 0.91. There was no significant difference in the accuracy of EUS and MDCT. Follow-up EUS (99%) was significantly more sensitive than MDCT (89% and 93%), as interpreted by two radiologists. Follow-up EUS was statistically significantly more sensitive than MDCT (96% vs. 70%) for one radiologist for tumors < 2 cm. Specificity of EUS was 50%, and sensitivity of EUS-FNA was 82%. Negative predictive value of EUS-FNA was significantly less in patients with (21%) than without (70%) biliary stents.

CONCLUSIONS

Follow-up EUS improves lesion detection over MDCT alone. Close follow-up/repeat biopsy should be considered if FNA is negative, but EUS is positive.

Quantitative preoperative assessment of vascular involvement in pancreatic carcinoma by multi-detector row computer tomography

AIM: To evaluate the clinical efficacy of multi-detector row computer tomography (MDCT) in the preoperative quantitative assessment of vascular involvement of pancreatic carcinoma.

METHODS: MDCT was performed on 42 pancreatic carcinoma patients; the celiac trunk and portal vein were reconstructed and their branches to three-dimension vessel were analyzed by volume rendering (VR) technique, multiplanar volume reconstruction (MPVR) and maximum intensity projection (MIP) technique. Combining the source images, the scope and extent of the vessel invaded in the portal vein celiac trunk, and inferior vena cava and their branches were evaluated and measured. Compared the CT scans results with operations and pathological sections, the diagnosis value of MDCT for pancreatic carcinoma was evaluated.

RESULTS: In the 42 pancreatic carcinoma patients with operation, 252 vessels were evaluated, 77 of which were invaded by carcinoma. Celiac trunks were invaded in 12 patients, and the sensitivity and specificity were 84.6% and 96.6%, respectively. Superior mesenteric arteries were invaded in 13 patients, and the sensitivity and specificity were 100% and 96.7%, respectively. Hepatic arteries were invaded in 9 patients, and the sensitivity and specificity were 81.2% and 100%, respectively. Portal veins were invaded in 16 patients, and the sensitivity and specificity were 93.3% and 92.6%, respectively. Inferior vena cava was invaded in 6 patients, and the sensitivity and specificity were 93.3% and 92.6%, respectively. Superior mesenteric veins were invaded in 21 patients, and the sensitivity and specificity were 90% and 86.7%, respectively. In the aspect of thrombosis, MDCT scan results were consistent with the surgical findings. Only one vessel of superior mesenteric artery and vein was not correctly measured in length by MDCT. When the length between invaded vessel and vessel branches was measured, only one patient's MDCT result was consistent with the surgical result on superior mesenteric artery.

CONCLUSION: MDCT can delineate the vascular involvement of pancreatic carcinoma with high accuracy, measure the invaded vessel correctly and provide valuable information for the preoperative assessment of pancreatic carcinoma.

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.

Pancreaticoduodenectomy for suspected malignancy: have advancements in radiographic imaging improved results?

BACKGROUND

The purpose of this study was to determine the impact of recent improvements in radiographic imaging in detecting malignant pancreatic disease.

METHODS

A review of 132 patients undergoing pancreaticoduodenectomy for suspected malignancy from 1998 to 2005 was performed. Since 1998, patients were evaluated with helical computed tomography and since 2002 with multidetection scanners.

RESULTS

Seventeen patients (12.9%) had nonneoplastic disease. The majority of these patients had chronic fibrosing pancreatitis (11 patients) and sclerosing lymphoplasmacytic pancreatitis (4 patients). The incidence of benign disease in patients undergoing resection from 1998 to 2001 (n = 45) was 8.9% in comparison to 14.9% for patients treated from 2002 to 2005 (n = 87, P = .39).

CONCLUSION

Advances in imaging modalities made during the study period did not improve our ability to discriminate between benign inflammatory conditions and neoplastic disease. The inability to distinguish benign from neoplastic disease justifies the use of pancreaticoduodenectomy in the appropriate clinical setting.

MDCT of pancreatic adenocarcinoma: optimal imaging phases and multiplanar reformatted imaging

OBJECTIVE

The objective of our study was to evaluate the individual contributions of arterial, pancreatic parenchymal, and portal venous phase (PVP) images and the utility of coronal and sagittal multiplanar reformatted (MPR) images in the assessment of pancreatic adenocarcinoma using triple-phase MDCT.

MATERIALS AND METHODS

Thirty-one patients with and 35 patients without pancreatic adenocarcinoma underwent triple-phase MDCT. Three radiologists independently attempted to detect pancreatic adenocarcinoma and assess local extension using the MDCT images in five sessions. The first three sessions involved sets of images obtained in arterial phase, pancreatic parenchymal phase, and PVP separately and respectively. In the fourth session, a combination of axial images from all phases was evaluated. During the fifth session, radiologists had access to coronal and sagittal MPR images together with the axial images obtained in all phases. Results were compared with surgical findings using receiver operating characteristic (ROC) analysis and kappa statistics.

RESULTS

Regarding tumor detection, the image set composed of coronal and sagittal MPR images and of axial images obtained in all phases had a significantly higher value for the area under the ROC curve (A(Z), 0.98 +/- 0.01) than the other image sets and yielded the highest sensitivity (93.5%). The sensitivity of the arterial phase image set (80.6%) was significantly lower than that of all other image sets. Whereas the image set composed of coronal and sagittal MPR images and axial images obtained in all phases yielded the highest kappa values for all local extension factors evaluated, the image set composed of only arterial phase images yielded the lowest kappa values for almost all of the factors.

CONCLUSION

A combination of pancreatic parenchymal phase and PVP imaging is necessary and efficient for the assessment of pancreatic adenocarcinoma. The addition of coronal and sagittal MPR images increased the performance of MDCT, especially in the evaluation of local extension.

New advances in pancreatic imaging

PURPOSE OF REVIEW

This review serves to highlight new technology and novel applications of existing techniques and their role in the management of pancreatic diseases, including acute and chronic pancreatitis, pancreatic cancer, and pancreatic cystic neoplasms.

RECENT FINDINGS

Contrast-enhanced ultrasound has shown promise in evaluating the severity of acute pancreatitis, staging pancreatic cancer, and predicting malignancy in cystic neoplasms. Optical coherence tomography within the pancreatic duct appears to be able to differentiate malignant and normal pancreatic ducts. Spectroscopy may prove useful in differentiating focal chronic pancreatitis from malignancy. Multidetector-row computed tomography may provide more accurate information regarding cancer respectability and differentiation between ductal type of intraductal papillary mucinous tumors.

SUMMARY

These new developments will help with the diagnosis and staging of pancreatic diseases.

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.