Rationale and Objectives
Pancreatic lesions are frequently detected in pancreatic phase only, which may lead to false negative findings in CT-guided biopsies. We evaluated the accuracy and complication rate of CT guided biopsies of pancreatic lesions with i.v.-contrast application following needle placement in comparison to biopsy after contrast enhanced CT.
Materials and Methods
In 30 patients planning and needle placement was performed on the basis of a native planning CT and prior diagnostic CT or MRT. After needle placement contrast enhanced CT was performed to confirm needle course and adjusted if necessary (group 1). In 30 additional patients biopsy was planned based on contrast enhanced CT and needle was placed in the lesion. Control scans confirmed correct needle position (group 2). An 18G coaxial system was used for both groups. Statistical analysis was performed with Student’s t and Fisher’s exact test for comparison of lesion size, location as well as accuracy and complication rates.
Results
Mean lesion size was significantly smaller in group 1 (31 mm vs. 39 mm; p = 0.02). Diagnostic accuracy and sensitivity for malignancy in group 1 was 93% and 92% versus 80% and 77% in group 2. Complications related to the procedure, i.e. haematoma (n = 5, group 1/n = 2, group 2) and pain (n = 0, group 1/n = 2, group 2) did not statistically differ.
Conclusion
CT-guided biopsy of pancreatic lesions with i.v.-contrast application following needle placement is a reliable method and provides superior accuracy compared to biopsies performed after contrast enhanced planning CT.
Computed-tomography (CT)-guided percutaneous biopsy of pancreatic lesions has become commonplace . Biopsies of the pancreas are performed to confirm a diagnosis of malignant pancreatic tumour, mostly ductal adenocarcinoma. Unfortunately, the majority of patients with carcinoma are diagnosed at advanced stage of the disease. Potentially curative resection can be performed in only about 10%–15% of these cases . Without treatment, the median survival time is reported to be only a few months . In several studies, both neoadjuvant radiochemotherapy and palliative chemotherapy were shown to improve survival rates .
However, in addition to the most frequent ductal adenocarcinoma, various other types of tumors with different prognosis and treatment options such as neuroendocrine tumors, lymphomas, ampullary tumors, or acinar carcinomas may give rise to a pancreatic mass. Thus, histologic assessment of any unclear lesion is required to establish the final diagnosis and to exclude patients with pseudotumors or benign lesions which would not undergo aggressive therapies . The sensitivity reported in biopsy studies ranges between 45% and 100% . The low sensitivity in some studies may be explained by the fact that several pancreatic lesions are only detected with cross-sectional imaging in special contrast phase scans, mostly in the arterial/pancreatic phase as hypoattenuating tumors from hypervascularization compared to healthy pancreatic tissue . In CT-guided biopsies, the poor or even absent delineation of the tumor at the time of biopsy/tissue sampling may lead to an increased number of false-negative biopsy findings. Therefore, the aim of our study was to evaluate the accuracy and complication rate of CT-guided biopsies of pancreatic lesions with intravenous contrast application following needle placement in comparison to a contrast-enhanced prebiopsy planning CT.
Material and methods
Patients
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Table 1
Gender, Mean Age of the Patients, Locations, Mean Sizes of the Lesions in Both Groups
Group 1 Group 2P Value Gender 14 ♂, 16 ♀ 15 ♂, 15 ♀ 1.00 Mean age (y) 63 64 .58 Lesion location (%): .10 Head 80.0 66.7 Body 6.7 26.7 Tail 13.3 6.7 Mean lesion size (mm) All lesions 31 ± 13 ( n = 30) 39 ± 12 ( n = 30) .02 Tumors 32 ± 13 ( n = 25) 39 ± 12 ( n = 27) .05 Nontumors 29 ± 9 ( n = 5) 36 ± 16 ( n = 3) .40 Incorrect diagnoses 27 ± 8 ( n = 2) 39 ± 7 ( n = 6) .10 Malignancy in biopsy_n_ = 23n = 20 0.57 Malignancy in final histology_n_ = 25n = 26 1.00 Correct final diagnosis_n_ = 28n = 24 .25 Complication rates Minor complications 5 4 1.00 Hematomas 5 2 .42 Pain 0 2 .37 Major complications 0 0
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Biopsy Technique
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Standard of Reference and Complications
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Statistical Analysis
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Results
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Table 2
Final Diagnoses of the Lesions in Both Groups
Final diagnoses: Group 1 ( n ) Group 2 ( n ) Tumors 25 27 Adenocarcinoma of pancreas 23 26 Carcinoma of choledochus 1 0 Neuroendocrine carcinoma 1 0 Neuroendocrine tumor 0 1 Nontumors 5 3 Chronic pancreatitis 2 2 Cicatricial tissue 0 1 Normal pancreatic tissue 3 0
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Table 3
Accuracy, Sensitivity and Specificity, Positive Predictive Value, and Negative Predictive Value for Malignancy in Both Groups
Group 1 Group 2 Accuracy 93% 80% Sensitivity 92% 77% Specificity 100% 100% Positive predictive value 100% 100% Negative predictive value 70% 40%
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Complications
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Discussion
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Limitations
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Conclusion
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