Ryan Niederkohr, M.D. Slides are not to be reproduced without permission of author

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1 Ryan Niederkohr, M.D.

2

3 CMS: PET/CT CPT CODES Limited Area (e.g., head/neck only; chest only) Regional (skull base to mid-thighs) True Whole Body (skull vertex to feet)

4 SELECTING FIELD OF VIEW REGIONAL ( eyes to thighs ) Longer acquisition time 7-8 beds / mins Fewer patients can be imaged per day Longer processing / reconstruction time Larger data set Greater radiation exposure Longer interpretation time LIMITED (e.g., chest) Shorter acquisition time 3-4 beds / 9-12 mins More patients could be imaged per day Shorter processing / reconstruction time Smaller data set Lesser radiation exposure Shorter interpretation time

5 QUESTION What is the estimated lifetime risk of a fatal cancer that is attributable to the ionizing radiation from a single CT scan of the abdomen in an adult (e.g., age 40 yrs)? A: 1 in 4 B: 1 in 2000 C: 1 in 5000 D: Negligible / too small to measure

6 ANSWER The correct answer is C. The risk of dying from cancer attributable to radiation exposure is dependent on dose and age at time of exposure. For a 40-year old man or woman, the risk of dying from cancer attributable to the ionizing radiation of one abdominal CT is approximately.02% = 1 in Answer A is incorrect. The lifetime risk of dying from cancer is 1 in 4. Answer B is incorrect. The lifetime risk of dying from cancer as a result of exposure to 1 rem of radiation is 1 in 2,000. Answer D is incorrect. Radiation risk is stochastic, meaning there is no threshold below which the risk is zero, or too small to measure. Reference: Brenner DJ, Hall EJ. Computed Tomography An Increasing Source of Radiation Exposure. N Engl J Med 2007;357;

7 1. Radiation Exposure kvp/mas Procedure W. body EDE Red marrow Breast Ovary Testes mrem PET 15mCi FDG /100 CT skull to thighs /100 CT chest /100 CT abd/pelvis

8 2. Interpretation Time

9 2. Interpretation Time H/N 79 slices Thorax 100 slices Abdomen / Pelvis (remainder) 55 slices To midthighs 48 slices

10 3. Disease-specific considerations Primary cancers below the diaphragm: Consider inclusion of the chest (to evaluate for pulmonary metastases). Primary cancers above the diaphragm: Inclusion of the entire abdomen / pelvis may not be necessarily warranted. In some cases, inclusion of liver/adrenals may be useful. Other primary cancers (e.g., lymphoma, melanoma) Routine inclusion of chest, abdomen and pelvis may be warranted. Consider neck / extremities on a case-by-case basis

11 CT FIELD OF VIEW RECOMMENDATION HEAD/NECK Neck Chest + ± Abd / Pelvis ESOPHAGUS NSCLC LYMPHOMA ± COLORECTAL (2008)

12 Lung Cancer 1026 PET scans 592 with new lung cancer 35 with possible M1 disease outside of thorax 9 False Positive 26 True Positive Aquino SL, Fischman AJ. Chest 2004; 126:

13 Seen on Limited Chest FOV Seen Only Outside Limited Chest FOV Liver 10 0 Adrenals 5 0 Spleen 2 0 Abdominal LN 3 0 Osseous Mets 12 1

14 Melanoma

15 Melanoma DISTRIBUTION OF PET ABNORMALITIES IN THE HEAD 296 SCANS 271 negative 25 positive 21 "anticipated" 4 "unanticipated" 2 True Positive 2 False Positive Niederkohr et al., Nuclear Medicine Communications 2007; 28:

16 Melanoma DISTRIBUTION OF PET ABNORMALITIES IN THE LOWER EXTREMITIES 296 SCANS 237 negative 59 positive 35 "anticipated" 24 "unanticipated" 11 "Likely Benign" 5 "Equivocal" 8 "Likely Malignant" 0 True Positive 5 False Positive Niederkohr et al., Nuclear Medicine Communications 2007; 28:

17 Head / Neck Cancer 38 patients primary tumor 26 PET/CT + Distant Malignancy / Metastasis 3 PET/CT + Lung Esophagus Sternum Wartski et al. Nucl Med Commun 2007;28:

18 Head / Neck Cancer 175 scans in 133 patients Lesions below adrenal glands in 7 patients (5.3%) Malignant Liver/bone mets (2 pts, 1.5%) Pancreatic Cancer (1 pt, 0.75%) Renal cancer (1 pt, 0.75%) Benign Colon Uptake (2 pts, 1.5%) Inguinal LN s (1 pt, 0.75%) Andrei Iagaru et al., SNM 2007 and RSNA 2007

19 CONCLUSIONS More is not necessarily better in terms of FDG PET/CT field of view. Limited body region FDG PET/CT may become standard practice for certain malignancies. Maintain consistency with standard practice guidelines. Particularly when performed in conjunction with optimized CT Limit radiation exposure Limit false positive diagnoses

20 CONCLUSIONS Regional (torso) PET/CT may remain standard for other malignancies. For example: Lymphoma Primary malignancies in the abdomen/pelvis Known (or suspected) disease above and below the diaphragm.

21 CONCLUSIONS Whole body PET/CT may retain an important role in the evaluation of selected patients. For example: Primary tumor in the extremities Sarcoma, melanoma, etc. Known (or suspected) metastatic lesions in the extremities Based on symptoms, exam, or other imaging findings