Nuclear Medicine

Nuclear medicine is a subspecialty of medicine that uses medically approved radioactive tracers called radiopharmaceuticals to assess bodily functions and to diagnose and treat diseases.
The Department of Nuclear Medicine at Amrita offers high quality state-of-the-art diagnostic and therapy services with state-of-the-art infrastructure, highly trained doctors and support staff. Nuclear medicine imaging provides superior diagnostic information based on physiological principles. It identifies disease very early at inception. It also provides guidance for initiating management and thereby provides better clinical outcome. All these investigations are safe and can be used in all age groups except in pregnant patients with relative contraindication in breast feeding patients.

Facilities

SPECT – Single photon emission computed tomography.
SPECT CT – Single photon emission computed tomography – computed tomography.
PET CT – Positron emission tomography – computed tomography.
PET MR – Positron emission tomography – Magnetic resonance imaging (3 Tesla).
Thyroid uptake probe – for estimating thyroid uptake function using I 131 radiotracer.
Gamma probe – gamma probe guided surgeries for parathyroid, sentinel node imaging & biopsy etc.
AERB approved therapy rooms - for procedures using beta and alpha particles –
a) Radio iodine therapy for hyperthyroidism, differentiated thyroid cancers,
b) I 131 – MIBG therapy for neuroblastoma,
c) Lutetium / Actinium DOTATATE (PRRT) therapy for neuroendocrine tumours,
d) Alpha therapy ( Actinium PSMA) for prostate cancer e) Ytrrium colloid for radiation synovectomy.
Special radiotracers for PET MR/ PET CT - Specific radiotracers for advanced PET CT / PET MR imaging are also available using molecules like flurodopa (parkinsonism, NET, pituitary lesions), choline ( liver/brain cancers) 18F MISO (hypoxic tracer, prior to radiotherapy planning) and 18F FLT (tumour proliferation).
The gamma camera services were launched in January 2000 with addition of high dose I 131 therapy for thyroid cancers in 2005. The department is equipped with latest state-of-the-art imaging instruments and special wards approved for radionuclide therapy. The department has grown in leaps and bounds in the past 21 years offering high-end services including MCI recognized post graduate (MD) Nuclear Medicine programme (started since 2012). State-of-the art PET CT service was inaugurated in 2008 by Ex President of India Shri A P J Abdul Kalam. The first state-of-the-art whole body PET MR facility in a university hospital and the third in the country was started in March 2018.

Procedures

What is SPECT & SPECT-CT ?

Single photon emission computed tomography involves acquisition of 3 D images using a gamma camera. When an additional CT counterpart is attached to the SPECT system, it is known as SPECT CT that provides additional anatomical information. Both these systems are available in the department. Medically approved gamma emitting radiotracers are used for imaging. Most commonly used radionuclide is 99mTechnetium labeled with various organ specific tracers like sestaMIBI, DTPA etc. Nuclear medicine imaging is popularly known as Scintigraphy (imaging the scintillations). Radioactive tracer in minute amounts is injected in the arm of the patient. After injection, the tracer gets localized in the organ of interest and starts emitting gamma rays that are perceived by a dual head gamma camera and its electronics. This scanner records the physiological alterations that take place in selected organs or body systems. The images are interpreted visually and quantitatively to look for pathological changes in any organ much earlier than anatomical imaging modalities. This imaging is fundamentally different from magnetic resonance imaging (MRI) and computed tomography (CT), for these methods only convey anatomic information. In most diseases, physiological changes precede anatomic changes, so scintigraphic evidence of a disease process can be diagnosed at an earlier stage. On the other hand, the MRI and CT are useful for clinical diagnosis after the disease process causes significant anatomic alterations.

Gamma Camera Procedures Performed

PROCEDURE	INDICATIONS
THYROID SCAN	To assess thyrotoxicosis, Graves disease, toxic MNG, thyroiditis, thyroid nodule evaluation, lingual thyroid etc
PARATHYROID SCAN	To assess parathyroid adenoma, hyperplasia, ectopic parathyroid adenomas
MYOCARDIAL PERFUSION/ THALLIUM SCAN	To evaluate IHD, physiological significance of known coronary stenosis, Coronary artery disease, False positive TMT, Baseline ECG changes like LBBB, Risk stratification of CAD, Presurgical cardiac evaluation, to assess myocardial viability before CABG prior to surgery for congenital heart disease, follow-up of Kawasaki disease
MUGA SCAN	To evaluate accurate LVEF, regional wall motion abnormalities in CAD, patients with obesity, COPD, prior to adriamycin and other cardiotoxic drug therapy
RENOGRAM	To assess GFR of individual kidneys esp. in donors, neonatal hydronephrosis, PUJ obstructions, obstructed megaureter. Relative functionevaluation in patients with renal malignancy prior to nephrectomy, ectopic kidneys, post renal transplant evaluations
DMSA SCAN	To assess UTI (Renal scars), ectopic kidneys, accurate function assessment of individual kidneys
DIRECT / INDIRECT RADIONUCLIDE MCU SCAN	To assess Vesico ureteric reflux, Urinary tract infections, hydroureteronephrosis
WHOLE BODY BONE SCAN	To evaluate skeletal metastases, bone malignancy, low backache, tuberculosis of bone, condylar hyperplasia, avascular necrosis, metabolic bone disease, stress fracture, osteomyelitis, cellulitis especially in diabetics.
GALLIUM CITRATE SCAN	Assessment of prosthetic infections, evaluation of lymphoma (Hodgkin’s & non Hodgkin’s), fever of unknown origin
LUNG PERFUSION & VENTILATION	Pulmonary embolism, lung vascularity assessment in children with congenital heart disease, predict FEV1 in patients planned for pneumonectomy/lobectomy
LIVER-SPLEEN SCAN	Alcoholic hepatitis, cirrhosis, portal hypertension, hemangioma, jaundice, Budd chiari syndrome.
HEPATOBILIARY SCAN	Differentiate neonatal hepatitis vs biliary atresia, postop bile leak, choledochol cyst, post liver transplant cases, gall bladder dyskinesia, acute/chronic cholecystitis.
MECKEL’S SCAN	Evaluation of meckels diverticulum (Ectopic gastric mucosa), malena, GI bleed.
GASTRO INTESTINAL BLEEDING	To evaluate occult GI bleed and localize the site of bleed
GASTRIC EMPTYING	For dyspepsia, vomiting, Diabetic gastroparesis.
GASTRO ESOPHAGEAL REFLUX (Milk scan)	Recurrent respiratory infections, heart burns
DACRYO SCINTIGRAPHY FOR EYES	To evaluate tear duct patency
SALIVAGRAM	To look for antegrade aspiration in young children

What is PET MRI ?

The ultimate hybrid imaging technology is the integration of PET and MRI (Magnetic resonance Imaging) providing exquisite structural, functional and metabolic details of suspected sites of cancer thereby increasing the accuracy of cancer detection. Certain tumours benefit by PET MR imaging than mere PET CT like gynecological malignancies, head & neck tumours, musculoskeletal, brain and liver cancers etc. With highest resolution, PET MR can identify tiny lesions easily. The biggest benefit to the patient is lack of additional radiation when an MRI is done. Like in PET CT, FDG and specific tracers like gallium PSMA, gallium DOTA, F DOPA, F MISO etc can be used to perform a PET MR study.
Other benefits:

Ease of getting two scans (PET & MRI scans) in one sitting with least patient discomfort.
Cost effective imaging (PET & MRI scans in one sitting).
Whole body coverage in integrated PET MRI imaging.
Less radiation procedure.
Modality of choice for early detection & therapy response of cancers especially in certain organs like brain, liver, uterus, cervix, tongue etc.

PET MRI in non cancer diseases detection

Brain:
There is a definite role for PET MRI hybrid scan in many non-oncological (non cancerous) diseases involving brain and heart. The structural changes in brain and heart can be so small that only exquisite structural information providing scans like MRI is imperative in the early detection of brain, heart diseases. Epilepsy and neuro degenerative diseases like dementia (i.e. memory disorders like Alzheimer’s disease), Parkinsonism can be effectively diagnosed early with PET MRI scanning.
Changes in brain morphology and cognitive impairment are diagnosed early due to the combined effort of PET MRI scanning in dementia evaluation. In epilepsy PET MR is used to localize the site of epileptic focus in medically refractory cases to plan surgery. It can accurately localize of origin of abnormal electrical impulses in brain by demonstrating FDG distribution changes. This is incremental when combined with 3 T MRI. Thereby the functional and anatomical information gathered by this single imaging modality is invaluable.
Heart:
Detection of viable (living) part of heart muscles is an integral part of coronary bypass surgery decision and this can be effectively & more accurately done by FDG PET MRI scanning. It can also detect inflammation of heart muscles (like cardiac sarcoidosis, viral myocarditis) very easily with utmost sensitivity. This can also be a useful investigation in assessing the treatment response.

What is PET CT ?

ONCOLOGY WORKUP 18 FDG (FLURODEOXYGLUCOSE)	Cancer staging, restaging, follow-up – brain tumor relapse, head and neck cancer, Ca of unknown primary, thyroid carcinoma, esophageal carcinoma, lung cancer, colorectal carcinomas, breast cancer, gynecological cancers, musculoskeletal tumors, malignant melanoma, prostate carcinoma, lymphomas, To assess RT / chemo response, For radiotherapy treatment planning. To evaluate solitary pulmonary nodule (benign vs malignant).
GALLIUM DOTA PET CT	Neuroendocrine tumors
GALLIUM PSMA PET CT	Prostate cancer
MYOCARDIAL PET CT (FDG)	Myocardial viability in coronary artery disease patients To look for myocardial ischemia To look for sarcoidosis To localize presence of absence of myocardial inflammation / infective endocarditis Intracardiac device infection
BRAIN PET CT (FDG)	To evaluate brain space occupying lesion To look for memory loss causes To look for Parkinson’s disease Evaluation of stroke, epilepsy Psychiatric illness Paraneoplastic disease workup Drug addiction studies
INFECTION PET CT (FDG)	To localize the site of occult infection in Pyrexia of unknown origin To confirm / rule out vasculitis To evaluate Prosthetic infection/ aseptic loosening of implants Diabetic foot complications like osteomyelitis/ charcots arthropathy

How hybrid PET/ MRI scanner works ?

MRI scanner uses a strong magnetic field to produce detailed images of internal structures of the body. They can also provide information about how well these structures are functioning.
PET scans use minute amounts of radioactive tracers (most of the time FDG fluorodeoxyglucose, a sugar molecule) to highlight cellular metabolic abnormalities indicating diseases like cancer.
Until now, scientists could not integrate PET and MRI for simultaneous scanning because MRI’s powerful magnets interfered with the imaging detectors on the PET scanner.
But now this hybrid imaging scanner PET MRI (first manufactured by Siemens Germany) is available worldwide & Amrita Hospital is the third hospital in India to acquire this state-of-the-art hybrid scanner.
It is possible to perform a whole body PET MRI or an organ specific PET MRI scanning depending on whether the patient is being imaged for cancer / non cancer organ specific diseases.
Once the radioactive injection is performed, the patient will wait approximately 60 minutes in a quiet area with limited body movement facilitating the distribution of radioactivity molecule. More radio tracer material is expected to accumulate in the cells with higher metabolism thereby identifying cancerous / non cancerous disease process of specific organs.
For the MRI portion, magnetic fields and radio frequency bursts will move the proton (hydrogen in cell) in the patient’s body out of their normal alignment or their normal spinning pattern. As the molecules return to their natural positions, the machine records that activity and medical image computers uses these information to create detailed and precise structural images of organs and tissues.
The images acquired from both PET-MRI scanners are then processed, aligned, fused and interpreted by trained, highly experienced nuclear & radiology imaging experts to diagnose and stage the cancer spread in the body.

Advantages of PET - MRI in cancer imaging

PET MRI is the ideal tool for staging most of the cancers at the time of detection.
MRI is the ultimate imaging technology in the accurate staging of local disease (T staging). It is especially true for primary cancers of specific sites like head & neck, pancreas, liver, prostate, gynaecological malignancies like cervix, uterus and cancers of muscles and bones especially in children.
In the detection and staging of lymph node spread of tumour the efficiency, sensitivity of PET & MRI added together improves the accuracy of lymph node (N staging) cancer spread.
PET MRI imaging is routinely performed as a whole body scanning. The biggest advantage of PET MRI scan (being a whole body scanning technique) is in the detection of unsuspected distant spread of cancers to organs like lungs, bones & other sites (M staging).
Effective TNM staging an integral part of cancer staging, treatment & prediction of prognosis is achieved by PET MRI Whole body imaging as an one stop shop procedure.
As both (PET MRI) imaging procedure is simultaneously performed it is an one time, less expensive, time saving smooth procedure for the patient.
This is an effective tool in the evaluation of response to treatment once cancer is diagnosed. In cases that are unresponsive to treatment, change of therapy makes a positive contribution to the course of the disease. Cancer treatment becomes more cost effective with PET MRI with the earlier evidence of therapy response or failure.
PET MRI Hybrid imaging is the imaging of choice in the evaluation and followup of childhood & adolescent patients’ cancers like lymphoma, neuroblastoma, brain tumours & sarcomas.