2004 SNM Mid-Winter Educational Symposium

Transcription

1 1

2 2

3 20 Numeric values SUV corr hs 18FDG Slope corr hs SUV corr hs Slope corr hs 11C-methionin 3

4 11C-methionine Grading and delineation of brain tumors Differentiation of malignant from benign SPN Staging in lung cancer Localization of enlarged parathyroid tissue 4

5 5

6 6

7 7

8 8

9 Problems in NET imaging In spite of pronounced hormonal symptoms, the tumors may be very small and difficult to detect. Tumors metastasize to various sites other than liver and lymph nodes e.g. bone, skin, lung, breast, pancreas, pleura, eye Staging of the tumor is needed before treatment and surgery. Improved sensitive imaging modalities are needed to detect residual or recurrent disease as early as possible. Patients: 18 patients with extensive disease; 14 MGC s, 1 foregut, 1 hindgut and 2 EPT s were examined with 11 C-5-HTP-PET and compared with CT. 10 patients were monitored with PET during treatment measuring SUV and transport rate constant (Patlak). 9

10 Results All patients showed an increased uptake of 11 C-5-HTP in tumor tissue (SUV ) The Patlak analysis indicated an irreversible trapping of 5-HTP in the tumors Patlak analysis in liver metastasis ( - ), lymph node metastasis ( - ) and normal liver ( - ) Tumor lesions in liver, pancreas, lymph nodes, pleura and bone were imaged by PET. PET detected a total of 232 lesions, whereas CT detected 155 lesions. PET demonstrated more lesions in 10/16 patients and equal number in 6/16. The high tumor-to-background ratio contributed to the better tumor visibility with PET. 10

11 Linear regression analysis showed a strong correlation between the changes in transport rate constant for 5-HTP and the changes in U-5-HIAA during medical treatment (r=0.907). Conclusions PET with 11 C-5-HTP allowed improved visualization compared to CT. Data on regional tumor metabolism provided additional information. The close correlation between the changes in 11 C-5-HTP transport rate and U-5-HIAA during medical treatment indicated the potential of 11 C-5-HTP-PET as a means to monitor therapy. Carbidopa pretreatment improves image interpretation and visualization of neuroendocrine tumors with 11C-5-HTP-PET 11

12 At 11 C-5-HTP-PET high urinary radioactivity concentrations of 11C in occasional patients leads to image artifacts which hampers image interpretation The aim was to investigate if blocking of the enzyme Aromatic Amino Acid Decarboxylase (AADC) could decrease the radioactivity concentration and thereby reduce this problem Carbidopa Conclusions Blocking of the enzyme AADC with Carbidopa in the dose of mg significantly reduced the urinary radioactivity concentration and increased the tumor uptake of 11 C-5-HTP. Carbidopa pretreatment reduced the image artifacts and facilitated tumor detection. Because of similar biochemical pathways, this method could probably be applied to improve PET-imaging also using tracers like 18 F-DOPA and 11 C-DOPA 12

13 Whole-body11C-5-HTP-PET as a general imaging technique for detection of Neuroendocrine tumors a comparison with somatostatin receptor scintigraphy (SRS) and computed tomography (CT) Whole Body PET with 11 C-5-HTP, pretreatment with 200mg Carbidopa Somatostatin Receptor Scintigraphy (Octreoscan ) Computed Tomography (CT) All examinations were performed within a period of w Inclusion criteria Histopathological diagnosis or biochemical evidence of a NET and detected lesion on conventional radiology or SRS 13

14 Conclusions WB-PET with 11 C-5-HTP can be used as a general imaging method for NET s. The method is sensitive in detecting small NETlesions, including the primary tumors, and the detection rate exceeds that of conventional imaging methods like SRS and CT. 11C-5-HTP-PET Final Conclusions I WB- 11 C-5-HTP-PET has a high tumor detection rate for NET s that surpasses both CT and somatostatin receptor scintigraphy (Octreoscan). 11 C-5-HTP-PET is sensitive in detecting small NETlesions and can contribute significantly to the patient management both in terms of the primary tumor detection and preoperative evaluation, as well as in staging and work-up concerning residual or recurrent disease. Final Conclusions II Non functioning tumors and poorly differentiated tumors are less well visualized with 11 C-5-HTP-PET. The use of premedication with Carbidopa, one hour before conducting 11 C-5-HTP-PET, greatly improved the image interpretation and tumor lesion detection. 14

15 Final Conclusions III There is a strong correlation between the change in transport rate constant and the change in U-5-HIAA during treatment, indicating that this technique can be used in treatment monitoring and perhaps response prediction of patients with NET s. SUV Time (months) Beta position Carboxy position 15

16 16

17 17

18 18

19 19

20 20

21 21