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Determination of Radiation Absorbed Dose to Primary Liver Tumors and Normal Liver Tissue Using Post-Radioembolization (90)Y PET.

Srinivas SM, Natarajan N, Kuroiwa J, Gallagher S, Nasr E, Shah SN, DiFilippo FP, Obuchowski N, Bazerbashi B, Yu N, McLennan G - Front Oncol (2014)

Bottom Line: Normal liver tissue received a mean dose of 67 Gy (mode 60-70 Gy; range 10-120 Gy).There was a statistically significant association between absorbed dose to normal liver and the presence of two or more severe complications (p = 0.036).Collateral dose to normal liver is non-trivial and can have clinical implications.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine, Cleveland Clinic , Cleveland, OH , USA.

ABSTRACT

Background: Radioembolization with Yttrium-90 ((90) Y) microspheres is becoming a more widely used transcatheter treatment for unresectable hepatocellular carcinoma (HCC). Using post-treatment (90) Y positron emission tomography/computerized tomography (PET/CT) scans, the distribution of microspheres within the liver can be determined and quantitatively assessed. We studied the radiation dose of (90) Y delivered to liver and treated tumors.

Methods: This retrospective study of 56 patients with HCC, including analysis of 98 liver tumors, measured and correlated the dose of radiation delivered to liver tumors and normal liver tissue using glass microspheres (TheraSpheres(®)) to the frequency of complications with modified response evaluation criteria in solid tumors (mRECIST). (90) Y PET/CT and triphasic liver CT scans were used to contour treated tumor and normal liver regions and determine their respective activity concentrations. An absorbed dose factor was used to convert the measured activity concentration (Bq/mL) to an absorbed dose (Gy).

Results: The 98 studied tumors received a mean dose of 169 Gy (mode 90-120 Gy; range 0-570 Gy). Tumor response by mRECIST criteria was performed for 48 tumors that had follow-up scans. There were 21 responders (mean dose 215 Gy) and 27 non-responders (mean dose 167 Gy). The association between mean tumor absorbed dose and response suggests a trend but did not reach statistical significance (p = 0.099). Normal liver tissue received a mean dose of 67 Gy (mode 60-70 Gy; range 10-120 Gy). There was a statistically significant association between absorbed dose to normal liver and the presence of two or more severe complications (p = 0.036).

Conclusion: Our cohort of patients showed a possible dose-response trend for the tumors. Collateral dose to normal liver is non-trivial and can have clinical implications. These methods help us understand whether patient adverse events, treatment success, or treatment failure can be attributed to the dose that the tumor or normal liver received.

No MeSH data available.


Related in: MedlinePlus

(A) shows a pink contour drawn around a tumor in an axial slice of the arterial phase abdominal CT scan. (B) shows the same tumor contour overlaid on the AC CT/PET fusion image that was acquired following left lobe 90Y microsphere therapy. (B) exhibits that contours drawn on the arterial CT show poor overlap with the corresponding region in the AC CT/PET fusion image. This can lead to inaccurate activity concentration determinations and necessitated the need to deform the arterial CT scan for more accurate contour statistic calculations.
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Figure 2: (A) shows a pink contour drawn around a tumor in an axial slice of the arterial phase abdominal CT scan. (B) shows the same tumor contour overlaid on the AC CT/PET fusion image that was acquired following left lobe 90Y microsphere therapy. (B) exhibits that contours drawn on the arterial CT show poor overlap with the corresponding region in the AC CT/PET fusion image. This can lead to inaccurate activity concentration determinations and necessitated the need to deform the arterial CT scan for more accurate contour statistic calculations.

Mentions: The 90Y PET/CT scan, which was required for determination of tumor radioactivity, typically showed poor overlap with the arterial and venous phase CT scans due to variations in position of patient, free breathing vs. breath hold, and time gap between the two acquisitions (see Figure 2). For this reason, the abdominal CT scan on which the tumor contours were drawn was deformed to match the AC CT corresponding to the PET scan using the deformation tools in MIM. The “reg refine” tool in MIM allowed us to fix points of interest that should be conserved in the deformation process. These points were mostly fixed around the liver edges since this was our organ of interest. Around 60 points were fixed around the liver in multiple planes and then the local alignments were converted into a deformable registration using the MIM deformation tool. The tumor contours drawn on the abdominal CT were deformed in the process as well.


Determination of Radiation Absorbed Dose to Primary Liver Tumors and Normal Liver Tissue Using Post-Radioembolization (90)Y PET.

Srinivas SM, Natarajan N, Kuroiwa J, Gallagher S, Nasr E, Shah SN, DiFilippo FP, Obuchowski N, Bazerbashi B, Yu N, McLennan G - Front Oncol (2014)

(A) shows a pink contour drawn around a tumor in an axial slice of the arterial phase abdominal CT scan. (B) shows the same tumor contour overlaid on the AC CT/PET fusion image that was acquired following left lobe 90Y microsphere therapy. (B) exhibits that contours drawn on the arterial CT show poor overlap with the corresponding region in the AC CT/PET fusion image. This can lead to inaccurate activity concentration determinations and necessitated the need to deform the arterial CT scan for more accurate contour statistic calculations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4195277&req=5

Figure 2: (A) shows a pink contour drawn around a tumor in an axial slice of the arterial phase abdominal CT scan. (B) shows the same tumor contour overlaid on the AC CT/PET fusion image that was acquired following left lobe 90Y microsphere therapy. (B) exhibits that contours drawn on the arterial CT show poor overlap with the corresponding region in the AC CT/PET fusion image. This can lead to inaccurate activity concentration determinations and necessitated the need to deform the arterial CT scan for more accurate contour statistic calculations.
Mentions: The 90Y PET/CT scan, which was required for determination of tumor radioactivity, typically showed poor overlap with the arterial and venous phase CT scans due to variations in position of patient, free breathing vs. breath hold, and time gap between the two acquisitions (see Figure 2). For this reason, the abdominal CT scan on which the tumor contours were drawn was deformed to match the AC CT corresponding to the PET scan using the deformation tools in MIM. The “reg refine” tool in MIM allowed us to fix points of interest that should be conserved in the deformation process. These points were mostly fixed around the liver edges since this was our organ of interest. Around 60 points were fixed around the liver in multiple planes and then the local alignments were converted into a deformable registration using the MIM deformation tool. The tumor contours drawn on the abdominal CT were deformed in the process as well.

Bottom Line: Normal liver tissue received a mean dose of 67 Gy (mode 60-70 Gy; range 10-120 Gy).There was a statistically significant association between absorbed dose to normal liver and the presence of two or more severe complications (p = 0.036).Collateral dose to normal liver is non-trivial and can have clinical implications.

View Article: PubMed Central - PubMed

Affiliation: Department of Nuclear Medicine, Cleveland Clinic , Cleveland, OH , USA.

ABSTRACT

Background: Radioembolization with Yttrium-90 ((90) Y) microspheres is becoming a more widely used transcatheter treatment for unresectable hepatocellular carcinoma (HCC). Using post-treatment (90) Y positron emission tomography/computerized tomography (PET/CT) scans, the distribution of microspheres within the liver can be determined and quantitatively assessed. We studied the radiation dose of (90) Y delivered to liver and treated tumors.

Methods: This retrospective study of 56 patients with HCC, including analysis of 98 liver tumors, measured and correlated the dose of radiation delivered to liver tumors and normal liver tissue using glass microspheres (TheraSpheres(®)) to the frequency of complications with modified response evaluation criteria in solid tumors (mRECIST). (90) Y PET/CT and triphasic liver CT scans were used to contour treated tumor and normal liver regions and determine their respective activity concentrations. An absorbed dose factor was used to convert the measured activity concentration (Bq/mL) to an absorbed dose (Gy).

Results: The 98 studied tumors received a mean dose of 169 Gy (mode 90-120 Gy; range 0-570 Gy). Tumor response by mRECIST criteria was performed for 48 tumors that had follow-up scans. There were 21 responders (mean dose 215 Gy) and 27 non-responders (mean dose 167 Gy). The association between mean tumor absorbed dose and response suggests a trend but did not reach statistical significance (p = 0.099). Normal liver tissue received a mean dose of 67 Gy (mode 60-70 Gy; range 10-120 Gy). There was a statistically significant association between absorbed dose to normal liver and the presence of two or more severe complications (p = 0.036).

Conclusion: Our cohort of patients showed a possible dose-response trend for the tumors. Collateral dose to normal liver is non-trivial and can have clinical implications. These methods help us understand whether patient adverse events, treatment success, or treatment failure can be attributed to the dose that the tumor or normal liver received.

No MeSH data available.


Related in: MedlinePlus