This study aimed at determining whether non attenuation corrected (NAC) positron emission tomogra... more This study aimed at determining whether non attenuation corrected (NAC) positron emission tomography (PET) images, in addition to the attenuation corrected (AC) PET images, should be included in the interpretation of fluoro-18 fluorodeoxyglucose ((18)F-FDG-PET) images in patients with lymphoma. The study included 58 patients, 35 males 23 females, mean age 55+/-16 years. There were 64 superficial and 170 deep lymph node (LN) lesions. Lesion detection, uptake intensity using a three-point scale (1-mild, 2-moderate, 3- intense) and overall clarity of each lesion were compared on both PET images. Our results showed that the detection rate for superficial LN was 100% for NAC-PET and 98.4% for AC-PET images. The degree of (18)F-FDG uptake (intense, moderate and mild uptake) was 56.3%, 31.3% and 12.5% for NAC-PET images and 23.4%, 34.4% and 40.6% for AC-PET images, respectively. The overall image clarity was significantly in favor of NAC compared to AC-PET images (89% vs 20%, P<0.01). For deep LN, lesions, detection rate was for NAC and AC-PET images 95.3% and 99.4%, respectively. (18)F-FDG uptake intensity (intense, moderate and mild uptake) was 42.4%, 27.1% and 25.9% for NAC and 52.4%, 43% and 4.1% for AC-PET images, respectively. The overall image clarity for AC-PET images was superior to NAC-PET images (81.8% vs 53% P=0.01). In conclusion, NAC-PET images appeared to be superior to AC-PET images in detecting superficial LN lesions. AC-PET images are superior to NAC-PET images with regard to the deep-seated LN lesions. Therefore, AC and NAC-PET images are complimentary to each other and require to be reviewed together in the evaluation of patients with lymphoma.
FDG-PET is of limited use in patients with early-stage disease without nodal or distant metastase... more FDG-PET is of limited use in patients with early-stage disease without nodal or distant metastases (stage I-II), because sentinel node biopsy is much more sensitive in detecting microscopic lymph node metastases. Because of the high tumor-to-background ratio, FDG-PET can highlight metastases at unusual sites that are easily missed with conventional imaging modalities. PET has been shown to have a strong role in detecting metastatic disease. FDG-PET is more sensitive than CT for detecting metastatic lesions in skin, lymph nodes, and abdomen, but CT is equivalent to or more sensitive than FDG-PET for detecting small pulmonary lesions. FDG-PET identifies the location and number of metastatic lesions in stage III and IV disease and therefore is important for surgical planning. Most of the false-negative FDG-PET results are caused by micrometastases and lesion smaller than 10 mm. Postsurgical inflammation, other inflammatory lesions, and some benign tumors cause some false-positive FDG-PET results.
This study aimed at determining whether non attenuation corrected (NAC) positron emission tomogra... more This study aimed at determining whether non attenuation corrected (NAC) positron emission tomography (PET) images, in addition to the attenuation corrected (AC) PET images, should be included in the interpretation of fluoro-18 fluorodeoxyglucose ((18)F-FDG-PET) images in patients with lymphoma. The study included 58 patients, 35 males 23 females, mean age 55+/-16 years. There were 64 superficial and 170 deep lymph node (LN) lesions. Lesion detection, uptake intensity using a three-point scale (1-mild, 2-moderate, 3- intense) and overall clarity of each lesion were compared on both PET images. Our results showed that the detection rate for superficial LN was 100% for NAC-PET and 98.4% for AC-PET images. The degree of (18)F-FDG uptake (intense, moderate and mild uptake) was 56.3%, 31.3% and 12.5% for NAC-PET images and 23.4%, 34.4% and 40.6% for AC-PET images, respectively. The overall image clarity was significantly in favor of NAC compared to AC-PET images (89% vs 20%, P<0.01). For deep LN, lesions, detection rate was for NAC and AC-PET images 95.3% and 99.4%, respectively. (18)F-FDG uptake intensity (intense, moderate and mild uptake) was 42.4%, 27.1% and 25.9% for NAC and 52.4%, 43% and 4.1% for AC-PET images, respectively. The overall image clarity for AC-PET images was superior to NAC-PET images (81.8% vs 53% P=0.01). In conclusion, NAC-PET images appeared to be superior to AC-PET images in detecting superficial LN lesions. AC-PET images are superior to NAC-PET images with regard to the deep-seated LN lesions. Therefore, AC and NAC-PET images are complimentary to each other and require to be reviewed together in the evaluation of patients with lymphoma.
FDG-PET is of limited use in patients with early-stage disease without nodal or distant metastase... more FDG-PET is of limited use in patients with early-stage disease without nodal or distant metastases (stage I-II), because sentinel node biopsy is much more sensitive in detecting microscopic lymph node metastases. Because of the high tumor-to-background ratio, FDG-PET can highlight metastases at unusual sites that are easily missed with conventional imaging modalities. PET has been shown to have a strong role in detecting metastatic disease. FDG-PET is more sensitive than CT for detecting metastatic lesions in skin, lymph nodes, and abdomen, but CT is equivalent to or more sensitive than FDG-PET for detecting small pulmonary lesions. FDG-PET identifies the location and number of metastatic lesions in stage III and IV disease and therefore is important for surgical planning. Most of the false-negative FDG-PET results are caused by micrometastases and lesion smaller than 10 mm. Postsurgical inflammation, other inflammatory lesions, and some benign tumors cause some false-positive FDG-PET results.
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