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Information about GENERAL PETCT LECTUREt.ppt1

Published on March 14, 2009

Author: drkmlakshmipathy



Status of PET-CT Current and Emerging Clinical Applications: : Status of PET-CT Current and Emerging Clinical Applications: DR.K.M.LAKSHMIPATHY Nuclear Medicine Physician PET-CT CENTRE ADYAR CANCER INSTITUTE (Unit.of Dr.Kamakshi Memorial Hospital ) NUCLEAR MEDICINE : NUCLEAR MEDICINE GAMMA CAMMERA Planar or Single Photon Emission Tomography (SPECT) TC99m ,Ga 67, In 111 Positron emission Tomography (PET) F18, O15, NH 13,C11 GAMMA CAMERA-SPECT : GAMMA CAMERA-SPECT Common H& N nuclear scans : Common H& N nuclear scans I-131 STUDIES : I-131 STUDIES I-131 DIAGNOSTIC &ROLE THERAPEUTIC : I-131 DIAGNOSTIC &ROLE THERAPEUTIC RADIO ACTVIE I-131 T1/2 8.3 DAYS BETA RAYS TRAVELS 2 MM IN TISSUE MECHANISM Molecular Imaging : Molecular Imaging Positive electron-positron : Positive electron-positron F18 CYCLOTRON PRODUCED : F18 CYCLOTRON PRODUCED F18 Radiopharmaceuticals : F18 Radiopharmaceuticals F18 FDG : F18 FDG PET-CT FUSION : PET-CT FUSION hybrid : hybrid horzeb Limitations of Imaging Anatomy1 : Limitations of Imaging Anatomy1 Detect masses, does not characterize them to a significant extent (fat, water, air) as to contents Show lymph nodes as present or absent but doesn’t reliably state what is within lymph nodes (45% sensitivity in colorectal ca. for ln involvement) Often difficult to detect small tumor foci, especially if surrounded by normal tissues. If small lesions identified, cannot be specific as to cause Performance less good in post operative state due to distortion of normal anatomy Limitations of Imaging Anatomy2 : Limitations of Imaging Anatomy2 Does not predict response to a given therapy Displays limited information re. Tumor biology (60% accurate for invasion) Slow to display response to treatment Difficult to measure cytostatic responses New imaging techniques, especially PET have potential to address limitations of anatomic imaging. Imaging: 100 Years of “ANATOMY” : Imaging: 100 Years of “ANATOMY” Anatomy Anatomy is and has been cornerstone of imaging for diagnosis, staging and follow up. Form has served us very well, X-Ray, US, CT, MRI etc. What is PET-CT? : What is PET-CT? Hybrid Imaging Device/Modality CT scanner (high quality images of anatomy) PET scanner (high quality images of function) Computer and software to fuse/display images No patient motion between studies Displays Anatomy, Function and the parameters fused in a series of images Look into the body, see what it is doing and where What are the benefits of PET-CT? : What are the benefits of PET-CT? Accurate spatial localization of abnormalities detected on PET—which can be VERY difficult to locate on PET alone Accurate determination of location of questionable abnormalities on PET—are they normal tissues with FDG uptake or tumor? What are the benefits of PET-CT? : What are the benefits of PET-CT? More rapid scans, less motion of patient Higher quality transmission counts/precision Consolidation of visits to imaging specialist Goal: Better Diagnostic Accuracy CT PET : CT PET PET-CT Clinical applications : PET-CT Clinical applications CANCER MANAGEMENT Detection of unknown primary, screening for secondaries and followup after RX NEUROLOGY eg.Alzeimers disease, seizures CARDIOLOGY evaluation of viability of myocardium. Molecular and Functional Alterations in Cancer . : Molecular and Functional Alterations in Cancer . Increased glucose metabolism Increased Amino acid transport Increased Protein and membrane synthesis Increased DNA synthesis Overexpression of receptors/antigens Increased blood flow or vessel density Decreased oxygen tension in lesions Increased apoptotic rates with effective Rx Cancer Imaging: The Questions : Cancer Imaging: The Questions Is cancer present (detection)? Is a mass cancer or not? Is the cancer localized or spread? How should the cancer be treated? Is a treatment working? Is more treatment needed? What is the prognosis? Does my new agent reach the target? Does my new agent perturb tumor physiology? Normal Tissues with FDG Uptake : Normal Tissues with FDG Uptake Normal Head and Neck: Tonsils Submandibular and Parotid Glands Cricoarytenoid muscles Minimize by NOT talking during uptake nor swallowing. CT scan protocol : CT scan protocol Patient is positioned head first and supine on the table Scanning begins from meatus of ear to mid thigh Shallow breathingduring the CT CT: What do I want to achieve? : CT: What do I want to achieve? Attenuation Correction Only Localization only Moderately high quality but modulated radiation dose for clear organ/lesion localization Diagnostic CT, non contrast Diagnostic CT, i.v. contrast How much of the body needs to be imaged? What radiation dose will I give and is it appropriate? Breathing management an issue PATIENT PREPARTAIONS : PATIENT PREPARTAIONS 4 HRS Empty stomach prior to study No strenuous physical actvity prior to study No talking or walking during or after injn.of F18 FDG No anti diabetic medication during the day of study prior to tracer injn. Fasting Blood sugar should be between 150 to 200 45 min to 1 HR following injn scan starts Duration of scan is approx.20 to 25 min. Quantitation : Quantitation SUV (standardized uptake value) = Tissue Concentration (KBq/g) Injected Dose (KBq) / Body Weight (g) Strauss and Conti. J Nucl Med 1991. SUV shows a strong positive correlation with patient body weight (i.e., overestimated in heavy patients). Zasadny and Wahl. Radiology 1993. Slide 39: HEAD AND NECK WALDEYER’S RING : WALDEYER’S RING NORMALS : NORMALS Axial 18FFDG PET/CT images show normal 18FFDG uptake in lymphoid tissues of nasopharynx (straight arrows) CA NASOPHARYNX : CA NASOPHARYNX CA NASOPHARYNX : CA NASOPHARYNX Eur J Nucl Med Mol Imaging. 2008 Aug 15. : Eur J Nucl Med Mol Imaging. 2008 Aug 15. In NPC patients, MRI appears to be superior to PET/CT for the assessment of locoregional invasion and retropharyngeal nodal metastasis PET/CT is more accurate than MRI for determining cervical nodal metastasis and should be the better reference for the neck status. PET/CT has an acceptable diagnostic yield and a low false-positive rate for the detection of distant malignancy and can replace conventional work-up to this aim PET/CT and head-and-neck MRI are suggested for the initial staging of NPC patients. The impact of 18F-FDG PET/CT on assessment of nasopharyngeal carcinoma at diagnosis : The impact of 18F-FDG PET/CT on assessment of nasopharyngeal carcinoma at diagnosis There is discordance between MRI and 18F-FDG PET/CT in the assessment of NPC at diagnosis The first is the potential for 18F-FDG PET/CT to distinguish reliably between oedema and tumour invasion in the bone marrow of the skull base, which could reduce the size of the GTV for radiotherapy. The second is the use of pre-treatment 18F-FDG PET/CT to aid the interpretation of any subsequent scans used to monitor early treatment response and detect residual cancer after treatment Slide 47: NORMALS parotid glands (large arrows), soft palate (arrowhead), spinal cord (small arrow) 14% of the patients, intense FDG uptake was seen in the parotid glands without specific symptoms SALIVARY GLANDS : SALIVARY GLANDS Conclusion: findings indicate that, in patients with salivary gland malignancies, 18F-FDG PET is clinically useful in initial staging, histologic grading, and monitoring after treatment but not in predicting patient survival NORMALS : NORMALS b) palatine tonsils (arrows ) CA TONSIL : CA TONSIL NORMALS : NORMALS c) lingual tonsils (arrows ) NORMALS : NORMALS d)SUBMANDIBULAR GLANDS Normals : Normals (e) sublingual glands and possible uptake in mylohyoid muscle (arrows); NORMALS : NORMALS (f) vocal cords (arrows) and posterior cricoarytenoid muscles (arrowheads). Rt vocal card palsy : Rt vocal card palsy Ca Esophagus Large active LYMPH NODE Slide 56: Nasopharynx LevelAt the upper level of the border between the hard and soft palates, the inferior concha generally showed low uptake activity Oropharynx LevelThe soft palate showed intense FDG uptake in 72% of the patients Hypopharynx LevelAt the level below the lower margin of the epiglottic vallecula, FDG uptake in the submandibular (Fig 1d) and sublingual (Fig 1e) glands was variable The vocal cords showed no or mild uptake in 81% of the patients TONGUE : TONGUE tongue had no or mild accumulation of FDG in 99% of the patients CA TONGUE : CA TONGUE THYROID : THYROID thyroid gland is usually depicted as a "cold" area INCREASED FDG UPTAKE IN THYROID : INCREASED FDG UPTAKE IN THYROID Slide 61: Conclusion: The incidental finding of increased 18F-FDG uptake in the thyroid gland is associated with chronic lymphocytic (Hashimoto's) thyroiditis and does not seem to be affected by thyroid hormone therapy. SUV correlated neither with the degree of hypothyroidism nor with the titer of TPO antibodies. Thyroid nodule : Thyroid nodule literature : literature Slide 64: HISTORY 28 Female Papillary thyroid Carcinoma and metastases Treated I-131 in 1993 Elevated TG and Negative I-131 PET – CT Recurrent Thyroid Carcinoma I-131 negative Slide 65: FINDINGS Focal increased FDG 2 Right lower cervical LN 1 Left paratracheal LN DIAGNOSIS Pathology – 4 positive LNs and positive midline LN papillary CA PET and Parathyroid : PET and Parathyroid In parathyroid disease, classical scintigraphic techniques remain the first choice for localizing hyperfunctional parathyroid glands in primary known hyperparathyroidism and in case of secondary, tertiary, and recurrent hyperparathyroidism. When classical scintigraphic techniques are not diagnostic, however, 11C-methionine seems to offer a good imaging alternative. 11C-methionine PET/CT in 99mTc-sestamibi-negative hyperparathyroidism in patients with renal failure on chronic haemodialysis Slide 67: Accounts for about 4,50,000 cases worldwide* 20% of cancer burden - 1,50,000 new cases in 2000 in India* TMH - 25% of all new cases annually > 75 % present with advanced disease Head and Neck Squamous Cell Carcinoma *Globocan,2002 IARC Detection of unknown primary : Detection of unknown primary Carcinoma of unknown primary of squamous cell origin : Carcinoma of unknown primary of squamous cell origin Rusthoven and coworkers(between 1992 and 2003):PET was performed after a negative endoscopy and negative CT and/or MRI ? the detection rate 27% Additional local and distant metastases:27% of patients The relatively high false-positive rate related to variable physiologic uptake of FDG in head and neck structures sensitivity(18 p’t) CT:PET:PET/CT=25%:25%:36% MUO-CA TONSIL : MUO-CA TONSIL Staging of primary disease : Staging of primary disease Rt vocal card palsy : Rt vocal card palsy Ca Esophagus Large active LYMPH NODE CA PYRIFORM FOSSA : CA PYRIFORM FOSSA A, Axial PET-CT demonstrates avid FDG uptake in a right pyriform sinus carcinoma and a metastatic right cervical lymph node. B, PET-CT of the chest shows a mediastinal mass with focal increased uptake. This was not detected on conventional radiography of the chest cervical adenopathy : cervical adenopathy hypermetabolic uptake at the right fossa of Rosenmuller, which proved to be nasopharyngeal carcinoma. Controversies: Is There a Role for Positron-Emission Tomographic CT in the Initial Staging of Head and Neck Squamous Cell Carcinoma? : Controversies: Is There a Role for Positron-Emission Tomographic CT in the Initial Staging of Head and Neck Squamous Cell Carcinoma? The current literature suggests that most primary site HNSCCA with volumes >1 mL will be FDG avid. These correspond to lesions that are moderately sized T1 or greater. Tumors with volumes <1 mL may be detected with FDG, however, the sensitivity decreases with decreasing size. PET also has the ability to detect metastatic cervical lymph nodes, which may be both clinically occult and not detected by CT or MR. In light of these potential benefits, there is debate as to how to use PET-CT for the initial staging of HNSCCA. American Journal of Neuroradiology 27:243-245, February 2006© 2006 American Society of Neuroradiology Response to chemo/radiotheray : Response to chemo/radiotheray Slide 77: -63 year-old man with local recurrence of tongue carcinoma 6 months after resection with negative margins during initial surgery (A). Maximum standardized uptake value of 7.69 was suggestive of recurrent disease, which was confirmed at subsequent biopsy. Follow up screening : Follow up screening Slide 79: metastatic cervical nodal disease of unknown primary. PET-LESION-right lobe of thyroid gland (arrowhead). primary thyroid cancer PET detected additional left supraclavicular nodal disease (arrowhead) that was not reported as pathologic on CT scan. This finding resulted in change in radiation target volume. High lights : High lights PET changes management plans and provides important prognostic information in a large proportion of patients with untreated head and neck cancer. PET also detects additional sites of disease and improves classification of patients into curative and palliative categories. NEURO PET : NEURO PET FDG-PET: Radiation Necrosis vs. Recurrent Brain Tumor : FDG-PET: Radiation Necrosis vs. Recurrent Brain Tumor Aggressive multimodality therapy (surgery, radiation, chemotherapy) standard care for many brain tumors CT and MRI unable to distinguish post-treatment necrosis from recurrent tumor FDG-PET shows hypometabolism with necrosis and maintained metabolism with tumor Sensitivity and specificity ? 80% (results best with co-registration) FDG uptake related to prognosis 2-4X longer survival with low vs. high metabolic activity Where is FDG PET Less Effective? : Where is FDG PET Less Effective? Hepatomas (half clear FDG activity rapidly) Renal Cancers (frequently difficult to distinguish from renal cortex and excreted activity) Prostate Cancers (majority lukewarm except some aggressive metastases) Tumors near uroepithelium (primary lesions) due to background activity What are roles of PET in Radiation Oncology : What are roles of PET in Radiation Oncology Precise delineation of location of tumor With PET/CT or markers, definition of normal tissues Potential assessment for hypoxia or other phenotypic features, proliferative rate etc. Assessments post therapy for adequacy of treatment, however more work is needed to determine how long residual FDG signal persists in varying situations Slide 88: Heron et al IJROBP,2004 Emerging Roles of PET and PET/CT : Emerging Roles of PET and PET/CT Radiation Therapy Planning Biological Tumor Volume vs. Anatomic Tumor Volume Differing field sizes common Changes in GTV common especially if there is parenchymal lung disease Reductions in normal lung irradiated PET : PET Evaluation of response to radiation and/or chemoradiation therapy : Evaluation of response to radiation and/or chemoradiation therapy Klabbers and coworkers(all FDG-PET studies for detection of residual and recurrent head and neck tumors after radiation and/or chemoradiation published between 1994 and early 2003) 3 to 4 months after radiation Evaluation of response to radiation and/or chemoradiation therapy : Evaluation of response to radiation and/or chemoradiation therapy When is the timing of the scan?? Rogers and coworkers:low sensitivity of 45% for a 1-month posttherapy FDG-PET Yao and coworkers( 15 patients ) :Comparing the 3- to 4-month posttherapy PET data with histology from salvage surgery ? sensitivity of 100% and specificity of 82% In summary, a PET scan performed 2 to 5 months after therapy has a high NPV so that patients can be safely followed without intervention Other Tracers for Clinical PET : Other Tracers for Clinical PET C11 Choline, F18 Choline C11 Acetate C11 Methionine--FET C11 Thymidine, F18 FLT F18 Misonidazole Cu 62 ATSM O 15 water 18 F NaF Slide 94: large anterior septal apical defect on stress that becomes normal at rest, Cardiac PET Dr KMH PET-CT : Dr KMH PET-CT Myocardial Viability - Mismatch TUBERCULOSIS -SPOIL SPORT : TUBERCULOSIS -SPOIL SPORT Infection associated with implants : Infection associated with implants Infection of vascular prosthesis is a serious, life-threatening condition Sterile inflammatory reaction to foreign body (mild diffuse FDG uptake) may be distinquished from infection (intense focal FDG uptake) Infection vs. inflammation (vascular prosthesis) Diffuse moderate FDG uptake bilaterally along the femoro-popliteal vascular prostheses represents a normal sterile inflammatory reaction to a foreign body. Focal increased FDG uptake in the left thigh (green arrow) represents infection. Clinical PET-CT Imaging : Clinical PET-CT Imaging Cancer 90% Brain 4% Cardiac 4% Other 2% Summary: Clinical PET-CT : Summary: Clinical PET-CT Oncologic applications are currently dominant Higher quality Diagnostic CT scans with contrast more common as “one stop” diagnostic tool with PET-CT Earlier use of PET-CT soon after therapy is initiated to perform “Risk Adaptive” treatment planning specific to the patient may become the norm Additional tracers and technical improvements will drive clinical PET forward in oncology Acknowledgements: : Acknowledgements: PET- CT CENTRE UNIT OF DR KM HOSPITAL CANCER INSTITUTE(WIA) ADYAR CHENNAI Slide 101: THANKS

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