SUMMARY OF PSYCHIATRIST GUIDE TO NUCLEAR MEDICINE Maroun Karam MD FACP Professor of Radiology and Nuclear Medicine

Somatic symptoms with frequent psychological causes Nausea and vomiting Abdominal pain Chest pain Generally the psychiatrist refers first to medical specialist to exclude organic cause but - some symptoms such as vomiting can be dramatic and require immediate attention - it is important to be aware of nuclear tests that can be done

Nausea, Flatulence and Dyspepsia, are non specific abdominal complaints commonly encountered in a primary care setting. Routine work-up is often unproductive. Two Nuclear medicine tests may provide an answer. 1. Measurement of gastric emptying 2. HIDA scan with measurement of GB EF for detecting biliary dyskinesia.

Common drugs and gastric emptying Erythromycin accelerates considerably GE Opiates slow down GE ( nausea as side effect) SSRI and most psychotropic drugs slow down GE ( except stimulants ) but stimulate appetite Antisecretory drugs slow down GE NICOTINE decreases significantly gastric emptying. This mechanism explains frequent gain weight after smoking cessation

GASTROPARESIS Definition: Delayed gastric emptying in the absence of mechanical obstruction. - Relatively uncommon as compared to other causes of nausea such as gastroenteritis - Very common in long-standing diabetes (30- 50%). - Diagnosis difficult to make on clinical grounds alone. - Present in over 40% of pts with severe reflux

Principles and technique Universal tracer : Technetium sulfur colloid Standard international meal - 2 slices of toast bread ml of eggwhite or “Eggbeaters”cooked - 30 gr of jelly mci Tc SC ( 50 times less than the dose for bone scan)

Normal Values * Tougas et al, Abell et al, Lin et al. Time Elapsed Lower Normal Limit for Gastric Emptying 60 min10% 120 min40% 240 min90% Values are the 95th%ile CI Nl 60 min 10-20% 120 min % 240 min %

Patient with long history of mental illness and daily vomiting Psychogenic? GE at 1 hr : 8% ( 10-40%) GE at 2hrs : 21% ( 40-80) GE at 4 hrs : 43% ( )

LESSON Measurement of GE can help distinguish psychogenic from real gastroparesis in pts with mental illness Discontinuation of opiates, erythromycine and psychotropic drugs 24 hr before the trst is necessary to avoid drug interference

Psychological symptoms Organic brain disease or mental illness At least 30% of patients with Alzheimer disease present with atypical symptoms mostly psychiatric such as agitation, hostile behavior, depression etc The opposite is true : 30% of elderly patients with cognitive decline DO NOT have dementia but underlying depression Some symptoms such as tremor may be psychogenic vs essential vs Parkinsonian Intermittent acute confusion may be due to occult temporal epilepsy

WHY IMAGE DEMENTIA? It is important for the psychiatrist to determine if there is underlying dementia because we have now at least symptomatic treatment for certain types In medico-legal cases the physician expert designated by the courts needs to show OBJECTIVE EVIDENCE OF DEMENTIA The best and most experienced physician will make diagnostic mistakes bases on clinical evaluation only (example : since we have Nuc imaging of Parkinsonian syndromes, when compared to postmortem evaluation there remains 10% error in clinical classification( essential tremor vs PD, PD vs APD) Clinical diagnosis of dementia by expert is only 65% accurate as compared to postmortem evaluation

Because MRI although very good to confirm or exclude vascular disease is limited for evaluation of other types of dementia Because the best way to detect dementia is through Molecular Imaging Molecular imaging is the visualization, characterization, and measurement of biological processes at the molecular and cellular levels in humans and other living systems The greatest fruits of this approach will be in understanding the brain and psychiatric illness because it has escaped so far detection with Conventional imaging For instance in AD FDG PET is more accurate than initial clinical evaluation ( sens 84% Spec 74% vs 66% and 58% ) FDG PET is more accurate in distinguishing FTD from AD than other methods ( Sens 96%, Spec 85% ) WHY NUCLEAR IMAGING?

WHY TRY TO DETERMINE THE TYPE OF DEMENTIA ? 1.Medications we are using for the symptomatic treatment of Alzheimer disease do not work on vascular dementia 2 Making a diagnosis of fronto- temporal dementia may have ethical implications ( 50% are familial : genetic counseling etc 3 Antipsychotic medications given to certain patients with dementia can be harmful If they suffer from fronto -temporal dementia 4There is at least one promising drug in clinical trial for AD

1.FDG ( fluoro 18 desoxyglucose)was discovered in 1976 and was used extensively in to study glucose brain metabolism but it remained limited to large research centers. Desoxyglucose is an analog of glucose labeled with F 18, a positron emitter 2. Many insights were gained about brain metabolism when the brain engages in Various mental functions and various patterns of neuronal loss in dementia 3. We have now almost 40 yrs of data on brain metabolism with FDG - in healthy brain : Before functional MRI we have detected what happens to Various brain areas during certain tasks ( reading, listening to music ) - we know what areas of the brain grow during certain development stages of the brain in the child - We have detailed regional changes of brain metabolism with age and we have Maps of brain FDG UPTAKE in normal individuals from age 50 to 90 - Plotting the findings of a patient against the data of age matched controls allows us to detect subtle regional abnormalities WHY PET HAS BECOME SO IMPORTANT? BECAUSE OF FGD NAMED BY TIME MAGAZINE MOLECULE OF THE CENTURY

Alzheimer’s disease is not the only cause of dementia. After age 85, 50% of individuals have dementia and 90% of these have AD Because of the aging of the population AD has become the major target of research

Fronto Temporal Dementia MRI was nl

TYPICAL FDG PET PATTERNS IN A: AD, B: DLB ( OCCIPTAL ) C: FRONTAL VARIANT FTD; D: NONFLUENT APHASIA FTD WITH MARKED ASSYMETRY INVOLVING L TEMP AND PAR LOBES

CLINICAL USEFULNESS OF FDG PET IN DEMENTIAS 1. Very effective in answering the question : Dementia or non dementia ? when symptoms are atypical or very mild. 2. Very effective in confirming vascular dementia ( random distribution of defects) 3. Very effective in confirming frontotemporal dementia ( SPECT as good as PET for this Indication but more difficult to obtain SPECT tracer than PET tracer in Lebanon ) 4. Moderately effective in distinguishing between AD and DLB ( Occipital involvement )

LIMITATIONS OF FDG PET IMAGING IN DEMENTIA FDG PET is excellent to confirm the diagnosis but is moderately effective to distinguish between AD and DLB When FDG PET becomes clearly positive there has been great amount of neuronal loss and it is probably too late to change the course of disease However until we have drugs that effect disease course this limitation is irrelevant

SOME IMPORTANT PRACTICAL CONSIDERATIONS Currently the only place I have access to do PET is LAU/Rizk hospital Through negotiations I was able to bring down the price of PET from 750 USD for cancer to 500 USD for brain only ( private payer ) and 600 (private insurance) Remains the problem of DAMAN I need your help If MRI has excluded vascular etiology how can we get DAMAN reimbursement for FDG PET? In the USA brain PET is also reimbursed for brain tumors and epilepsy diagnosis