Does chemotherapy influence the quantification of SUV when contrast-enhanced CT is used in PET/CT in lymphoma?
OBJECTIVE
In patients with lymphoma, we investigated the impact of contrast-enhanced CT on PET attenuation correction in lesions and normal tissues, particularly when PET/CT was performed after chemotherapy.


METHODS
Fifty patients (51+/-18 years) with Hodgkin's disease (n=17) or non-Hodgkin lymphomas (n=33) were studied before and after chemotherapy. PET/CT scans were performed 60 min after injection of FDG. Iopamiron 300 (iopamidol, 1.5 cc/kg) was injected immediately afterwards, followed 50 s later by a second craniocaudal CT (CT+). PET images were successively reconstructed using the unenhanced CT (PET-) and the CT+ (PET+) for attenuation correction, using iterative reconstruction (4 iterations, 8 subsets, 5 mm post-filtering). HU(mean), SUV(max) and SUV(mean) were measured before and after chemotherapy in ten non-tumoural ROIs [aorta, femur, kidney, lung, iliopsoas muscle, occipital cortex, T12 vertebra, liver, spleen and inferior vena cava (IVC)] and in tumoural lymphadenopathies or malignant tissues (n=397 and 51 VOIs respectively before and after chemotherapy) using a 3D-thresholding method (identical threshold for PET- and PET+). ROIs were defined on the PET- and automatically applied on the unenhanced CT (CT-), the CT+ and the PET+.


RESULTS
In the non-tumoural tissues, HU(mean) increased significantly in the CT+ compared with the CT- in the vessels and the highly vascularised organs, and slight increases were observed in the occipital cortex (+11%), the iliopsoas muscle (+6%) and the femur (+3%). SUV(max) increased significantly in the PET+ compared with the PET- in the aorta (+14%), the liver (+10%), the spleen (+10%) and the IVC (+12%). SUV(mean) increased significantly in the PET+ compared with the PET- in the aorta (+15%), the kidney (+13%), the liver (+11%), the spleen (10%) and the IVC (+12%). In the lesions, HU(mean) was not significantly different before and after chemotherapy, whatever the normal region considered. SUV(max) increased significantly after treatment in the T12 vertebra (+12%). SUV(mean) increased significantly after treatment in the T12 vertebra (+13%) and in the liver (+12%). HU(mean) increased significantly in the CT+ compared with the CT- in the lesions (+55%) before chemotherapy. SUV(max) and SUV(mean) increased significantly in the PET+ compared with the PET- in the lesions (+4%) only before chemotherapy. No significant difference was seen in measurements (HU(mean), SUV(max) and SUV(mean)) after chemotherapy.


CONCLUSIONS
Our study demonstrates that use of enhanced CT for attenuation correction has a negligible effect on quantification at staging and after chemotherapy. A "single-shot" enhanced PET/CT may thus be performed in the evaluation of patients with lymphoma at staging, during treatment and at follow-up.
Vera
Pierre
P
Department of Nuclear Medicine, Henri Becquerel Centre and Rouen University Hospital, 1 rue d'Amiens, Rouen, France. pierre.vera@rouen.fnclcc.fr
Ouvrier
Matthieu John
MJ
Hapdey
Sébastien
S
Thillays
Marc
M
Pesquet
Anne Sophie
AS
Diologent
Brigitte
B
Callonec
Françoise
F
Hitzel
Anne
A
Edet-Sanson
Agathe
A
Ménard
Jean François
JF
Jardin
Fabrice
F
Tilly
Hervé
H
D000970:Antineoplastic Agents / Q000008:administration & dosage*; D016477:Artifacts; D003287:Contrast Media; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*
D000970:Antineoplastic Agents; D003287:Contrast Media
Eur J Nucl Med Mol Imaging. 2005 Oct;32(10):1167-75
15909196
AJR Am J Roentgenol. 2006 Nov;187(5):W498-502
17056880
Eur J Nucl Med Mol Imaging. 2002 Jul;29(7):922-7
12111133
J Nucl Med. 2002 Sep;43(9):1129-36
12215549
Eur J Cancer. 1999 Dec;35(13):1773-82
10673991
Blood. 2006 Jan 1;107(1):52-9
16150944
Clin Nucl Med. 2000 Nov;25(11):905-10
11079589
J Nucl Med. 2005 Mar;46(3):429-35
15750155
Eur J Nucl Med Mol Imaging. 2004 Mar;31(3):325-9
14647988
Q J Nucl Med. 2002 Mar;46(1):24-34
12072843
Ann Oncol. 2005 Sep;16(9):1514-23
15980161
J Nucl Med. 2005 Jun;46(6):983-95
15937310
J Nucl Med. 2006 Aug;47(8):1326-34
16883013
J Nucl Med. 2006 Oct;47(10 ):1643-8
17015900
AJR Am J Roentgenol. 2006 Feb;186(2):308-19
16423932
AJR Am J Roentgenol. 2002 Dec;179(6):1555-60
12438054
Cancer. 1997 Dec 15;80(12 Suppl):2505-9
9406703
Br J Radiol. 2006 Jan;79(937):32-6
16421402
J Nucl Med. 2004 May;45(5):784-8
15136627
Br J Radiol. 2004 Aug;77(920):662-5
15326044
J Nucl Med. 2006 Mar;47(3):470-6
16513616
Eur J Nucl Med Mol Imaging. 2004 Jan;31(1):22-8
14574514
Blood. 2005 Aug 15;106(4):1376-81
15860666
J Nucl Med. 2005 Feb;46(2):283-91
15695788
Radiology. 2002 Nov;225(2):575-81
12409597
Radiology. 2003 Jun;227(3):817-24
12773683