Nuclear Medicine

• Diagnostic nuclear medicine imaging is unique, as it helps to view how the body is functioning. X-rays and CT scans help to view how the body looks rather than how it works.
• Diagnostic nuclear medicine imaging involves the administration of trace quantities of radiopharmaceuticals / radiolabeled normal constituent body molecules / radioisotopes, for diagnosing
  a) Various abnormalities occurring at a biochemistry level (ex. measuring glucose metabolism)
  b) Functional abnormalities (ex. differentiation of obstructive and non-obstructive hydronephrosis)
• It can diagnose structural abnormalities as well.
• Overall, this sharply contrasts with radiology, which usually provides anatomical information only.
• Pregnancy is a contraindication

• Includes Gamma Cameras and PET-CT scanners.
• With scintillation Gamma cameras and PET scanners, in a typical interaction, a crystal inside them scintillates (conversion into light form) proportional to the incident gamma ray. This is further processed, to generate an image of the biodistribution of the radiopharmaceuticals / radiolabeled normal constituent body molecules / radioisotopes.

Our country possesses approximately 170 billion barrels of oil that can be recovered with today’s technology. Of that number, 165 billion barrels are located in the oil sands.

• Different pharmaceuticals are meant for different organ systems (ex. Iminodiacetic agents for Hepatobiliary system).
  Unrelated to this, the pharmaceuticals can serve as markers (ex. tumour markers).
  Radioisotopes are tagged with the appropriate pharmaceuticals, so that the radiation emitted, is tracked now, to form an image of the biodistribution of the now radiopharmaceutical.
  Pharmaceuticals here are the ‘pullers’ and the radioisotopes, ‘the pulled’ ones.
• Radiolabeled normal constituent body molecules too serve as markers (ex.metabolic markers). The product preparation involves procedures like radioisotope incorporation of target molecules, radiosynthesis follow through, etc…
• For some studies, only the radioisotopes are used, as they have their own biodistribution.

• For the most part, nuclear scans are safe tests. Allergic reactions to the radiotracers are extremely rare and are usually mild.
• For an effective dose of 10 mSv from a nuclear medicine procedure, 0.05% of the patients who have the test develop a fatal cancer sometime later in their life. This risk is negligible, compared with the natural prevalence of fatal cancer, which is 22%.
• Also, the risk is negligible when compared with the benefits from the procedure.

1. Yes. However, because the administered radiation doses are extremely small for diagnostic purposes, and since the majority of diagnostic nuclear medicine imaging procedures involve the emission of diagnostic quality gamma rays, the radiation exposure to the patients is minimal, acceptable for diagnostic exams.
2. • For those diagnostic nuclear imaging procedures involving radioisotopes like Iodine-131, which are both beta ray (imageable) and gamma ray (imaged) emitters , the radiation dose to the patients is still minimal only.
   • In general, radiation dose from diagnostic nuclear medicine imaging procedures is similar to that from diagnostic radiological procedures and to that from background radiation.

Difficult to answer.

• Exposure to high levels of ionizing radiation can lead to unwanted health effects, including cancer.
• It is considered prudent for public safety to assume that exposure to ionizing radiation, no matter how small, carries some small risk of unwanted health effects, including cancer.

1. This can vary from study to study. For example, a Tc99m thyroid scan is usually completed within 30 minutes from the time of injection, whereas a Tc99m sestamibi stress + rest cardiac scan can consume the day from morning to evening.

1. Except for the pain of intravenous injections, nuclear medicine procedures are generally painless and are rarely associated with significant discomfort or side-effects.{(Most of the diagnostic nuclear medicine imaging procedures involve the i.v. administration of radiotracers( through a peripheral route)}.
2. Some of the radiotracers need to be administered orally. They have little or no taste.
3. With some procedures, a catheter may have to be inserted into the urinary bladder, which may cause temporary discomfort.

• Enables quick, personalized management of each patient.
• Can safely view and help in treating disease, avoiding invasive procedures.
• Can find and characterize disease in almost every organ system including heart, brain, skeleton, thyroid, kidneys and also in many types of cancer.
• Can be used to treat diseases without surgery in specific circumstances.
• For many diseases, nuclear medicine scans yield the most useful information needed to make a diagnosis or to determine appropriate treatment.
• Nuclear medicine procedures are less expensive and can yield more precise information than even procedures like exploratory surgery.
• When nuclear medicine procedures are performed at the right time, it will be of a great clinical benefit.

• Benefits of diagnostic nuclear medicine imaging (using a Gamma Camera / PET-CT scanner) include:
  1. Provides unique information by non-invasive means {ex. measuring glucose metabolism using glucose analogues (glucose metabolism is increased in many malignancies), functional significance of coronary stenoses seen on coronary angiography /CT-angiography, assessment of functional biliary pain in adults, etc.…}.
  2. Enables to detect disease in its earliest stages, often before symptoms occur / abnormalities on conventional imaging modalities.
  3. Accurate staging.
  4. Detects malignant transformation of benign lesions, early.
  5. Helps in avoiding unnecessary surgeries.
  6. Treatment response assessment (Early, Interim stages; Post-therapy).
  7. Differentiates tumour recurrence from radiation necrosis.
  8. Prognostication
  9. Risk assessment
  10. Helps in Radiation therapy planning (Target volume selection, Target volume delineation).
• Salient features of diagnostic nuclear medicine imaging (using a Gamma Camera / PET-CT scanner) include:
  1. Non-invasive.
  2. Whole body evaluation can be performed.
  3. Done as outpatient procedures.
  4. Dose to the patients from radiation exposure is minimal.

• Salient features of diagnostic nuclear medicine imaging (using a Gamma Camera / PET-CT scanner) include:
  1. Non-invasive.
  2. Whole body evaluation can be performed.
  3. Done as outpatient procedures.
  4. Dose to the patients from radiation exposure is minimal.

• Therapy in Nuclear Medicine involves the administration of higher amounts of radioisotopes / radiopharmaceuticals to treat various diseases (ex. Iodine-131 therapy for hyperthyroidism, Sm-153 EDTMP therapy for bone pain palliation, etc…).
• As part of this, imaging may have to done, as and when required.
• Some of the therapeutic nuclear medicine procedures are done as inpatient procedures.
• Pregnancy is a contraindication.

• The images obtained in diagnostic nuclear medicine can be in a planar form (like an X-ray), in a cross-sectional form (like a CT) {ex. Single Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET) or Dual Photon Emission Computed Tomography} or in a 3 dimensional form. (The image from the dual photon emitters can be in the planar form too)

• A PET-CT scanner is an integrated device containing both a PET scanner and a CT scanner with a single patient table, and therefore capable of obtaining a PET scan, a CT scan, or both. If the patient does not move between the scans, the reconstructed PET and CT images will be spatially registered. It uniquely combines the functional information provided by the PET scan and the anatomical information provided by the CT scan.
• PET-CT fusion is the combined display of registered PET and CT image sets.

• It involves the use of positron emitters (ex. Fluorine-18, Nitrogen-13, Carbon-11, Oxygen-15), where a typical radioactive decay leads to the detectable emission of two gamma rays in exactly opposite directions, within a specified period of time (dual photon or positron imaging).

• It involves the use of radioisotopes like Tc99m, where single gamma rays are emitted from radioactive decays (single photon imaging).
• Cross-sectional imaging in this category is called SPECT.

Oncology Hodgkin’s Lymphoma Lymphoma

• Workup, Restaging after primary treatment, Restaging after 2nd line systemic therapy, Restaging after 2nd line therapy in relapse, Surveillance

Non-Hodgkin’s Lymphomas

Work up, Treatment response assessment (including Initial therapy, End-of-treatment response, Before 2nd line and subsequent therapy, In histologic transformation, Induction therapy, End of treatment restaging, Follow up therapy, Therapy response in relapse, etc.…), Prognostication, Histologic transformation assessment, Relapse, Surveillance

Nodule suspicious for Lung cancer:

• Diagnostic Evaluation

Non-Small Cell Lung Cancer (NSCLC):

• Pretreatment evaluation, Suspected multiple lung cancers, Recurrence, Treatment response assessment / Surveillance

Patient of NSCLC with a true positive right paratracheal node at surgery. {Borderline significance on CT size criteria alone (< 1 cm in its short axis), but is clearly FDG avid positive on PET/CT)}

Head and Neck Cancers:

• Work up of Cancer of Lip, Cancer of oral cavity, Cancer of Oropharynx, Cancer of hypopharynx, Cancer of Nasopharynx, Cancer of glottic larynx, Cancer of Supraglottic larynx, Ethmoid sinus tumours, Maxillary sinus tumours, Salivary gland tumours, Mucosal malignant melanoma.
• Work up of Occult primary
• Post chemoradiation or RT neck evaluation, Recurrence, Surveillance

A 61 year old man with right side cervical lymphadenopathy proved to be carcinoma of unknown primary. Patient underwent F-18 FDG PET/CT. Axial PET, CT, PET/CT and MIP images are shown. PET/CT showed asymmetrical FDG uptake in the palatine tonsils with intense FDG uptake in the right tonsil (black arrow) as well as multiple hypermetabolic cervical lymph nodes in the right side (red arrows). This patient subsequently underwent surgical resection and histopathology revealed squamous cell carcinoma in the right tonsil. PET/CT was valuable in revealing the primary tumour in this case.

Recurrent tumour in a 61 year old patient with a history of squamous cell carcinoma of the right base of tongue. The patient had undergone extensive resection of the primary tumour. CT and F-18 FDG PET-CT were performed to investigate the cause of recurrent pain. a) CT scan fails to demonstrate recurrent neoplasm (arrow). b) PET-CT scan shows focal intense FDG uptake in the supraglottic larynx (arrow), a finding that proved to be recurrent neoplasm.

HNSCC metastasis from unknown primary tumour. Patient had enlarging 3-cm left neck mass felt on physical examination. A) Contrast-enhanced CT depicted space-occupying lesion (red arrow) in left neck. Biopsy of lesion was obtained by fine-needle aspiration, and lesion was proven to be lymph node metastatic squamous cell carcinoma. There was no clear evidence of primary tumour except for subtle asymmetry at left tonsillar fossa (blue arrow) that was of uncertain significance. 18F-FDG PET (B) and fusion PET/CT (C) clearly identified primary tumour at left tonsillar fossa (arrows); findings was confirmed by endoscopic biopsy.

Detection of unexpected malignant involvement of lymph nodes at initial staging. Patient with locally advanced nasopharyngeal cancer for initial staging evaluation. Contrast-enhanced CT (A) and MRI (B) revealed 2 lymph nodes that were within normal limits by size criteria and for which the presence of malignant disease was uncertain (arrows). (C) These 2 nodes clearly had abnormal activity on 18F-FDG PET/CT (arrows), and radiation treatment field was adjusted to accommodate these regions.

Esophageal and Esophagogastric junction cancers

• Work up, Recurrence, Treatment response assessment / Surveillance

PET (A), coregistered CT (B), and fused PET/CT (C) images in patient undergoing primary staging for a lower esophageal cancer. PET/CT demonstrated intense F-18 FDG activity in the primary tumor and metastatic nodal disease in a periesophageal (red arrows) and a left gastric node (yellow arrows), which were not considered pathologically enlarged on prior staging dedicated CT. A left adrenal lesion was of indeterminate etiology on CT but was intensely F-18 FDG–avid compatible with a distant metastasis (orange arrows). Planned curative surgery was avoided and the patient received palliative treatment. The left adrenal metastasis was confirmed by progressive enlargement on serial imaging.

Gastric Cancer

• Work up, Treatment response assessment / Surveillance

Colon Cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Rectal Cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Anal cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Breast Cancer

Invasive Breast Cancer (Non-inflammatory)

• Workup, Recurrence, Treatment response assessment / Surveillance

Inflammatory Breast Cancer

• Work up

Phyllodes tumour Recurrence Thyroid Cancer

Papillary / Follicular carcinoma (including Hurthle cell carcinoma) {when I-131 imaging is negative and stimulated Tg > 2-5 ng/ml}

• Work up, Recurrence, Treatment response assessment / Surveillance

Anaplastic carcinoma

• Diagnostic procedure, Staging, Recurrence, Treatment response assessment / Surveillance

48 year old female with papillary thyroid cancer treated by subtotal thyroidectomy, followed by ablative dose of Iodine-131 (100 mCi); On follow up, Iodine-131 whole body scintigraphy was negative for any residual tumour or metastases (A), yet the Tg was remarkable elevated. PET(C) and PET/CT (D) revealed increased activity of F18-FDG uptake at the right lung (arrow heads) not evident in corresponding conventional CT image (B).

Testicular Cancer Pure seminoma

• ( Post chemotherapy assessment – Recurrence – Post- chemotherapy Surveillance)

Bone Cancer Chondrosarcoma

• Recurrence, Treatment response assessment / Surveillance

Chordoma

• Work up, Recurrence, Treatment response assessment / Surveillance

Ewing’s Sarcoma Family of Tumours

• Work up, Restaging, Relapse, Treatment response assessment / Surveillance

Osteosarcoma

• Work up, Relapse, Treatment response assessment / Surveillance

Giant Cell Tumour of Bone

• Work up, Recurrence, Treatment response assessment / Surveillance

Multiple Myeloma

• Work up, Relapse, Treatment response assessment / Surveillance

Neuroendocrine Tumours Neuroendocrine Tumours of the GIT, Lung and Thymus (Carcinoid Tumours)

• Evaluation, Recurrence, Treatment response assessment / Surveillance

Neuroendocrine Tumours of the Pancreas

• Recurrence, Treatment response assessment / Surveillance

Neuroendocrine Tumours of Unknown Primary

• Work up

Poorly Differentiated (High Grade) NET / Large or Small Cell carcinoma other than Lung

• Evaluation, Recurrence, Treatment response assessment / Surveillance

Adrenal Gland Tumours

• Evaluation in suspected carcinoma
• Carcinoma – Staging, Recurrence, Treatment response assessment / Surveillance

Pheochromocytoma / Paraganglioma

• Evaluation, Recurrence, Treatment response assessment / Surveillance

Thymomas and Thymic Carcinomas

• Evaluation

Occult Primary (Cancer of Unknown Primary – CUP)

• Initial evaluation, Additional work up

Cervical Cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Ovarian Cancer (including Fallopian tube cancer and Primary peritoneal cancer)
Epithelial Ovarian Cancer / Fallopian tube cancer / Primary peritoneal cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Malignant Germ Cell Tumours

• Evaluation, Recurrence, Treatment response assessment / Surveillance

Uterine Neoplasms Endometrial Carcinoma

• Work up, Recurrence, Surveillance

Uterine Sarcoma

• Additional evaluation, Recurrence, Treatment response assessment / Surveillance

Soft tissue sarcomas Extremity / Superficial trunk / Head & Neck

• Workup , Recurrence, Treatment response assessment / Surveillance

Retroperitoneal / Intraabdominal

• Recurrence, Treatment response assessment / Surveillance

GIST

• Workup, Treatment response assessment / Surveillance

Desmoid tumours (Aggressive fibromatosis)

• Recurrence, Treatment response assessment / Surveillance

Rhabdomyosarcoma (excluding those identified within another histology)

• Initial staging
• Work up, Recurrence, Treatment response assessment / Surveillance – for Non-pleomorphic rhabdomyosarcoma

Melanoma

• Work up, Treatment response assessment, Recurrence, Surveillance

Pancreatic Adenocarcinoma

• Work up, Recurrence, Treatment response assessment / Surveillance

Kidney Cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Urinary Bladder Cancer

• Work up, Recurrence, Treatment response assessment / Surveillance

Prostate Cancer

• Staging work up, Treatment response assessment, Radical prostatectomy biochemical failure, RT recurrence

Hepatobiliary Cancers Hepatocellular carcinoma

• Work up, Recurrence, Treatment response assessment / Surveillance

Gall Bladder Cancer, Intrahepatic and Extrahepatic Cholangiocarcinomas

• Recurrence, Treatment response assessment / Surveillance

CNS cancers Adult Low-Grade Infiltrative Supratentorial Astrocytoma / Oligodendroglioma (excluding PiIolcytic Astrocytoma)

• Work up, Recurrence, Treatment response assessment / Surveillance

Anaplastic Gliomas (includes classification of mixed anaplastic oligoastrocytoma, anaplastic astrocytoma, anaplastic oligodendroglioma and other rare anaplastic gliomas) / Glioblastoma

• Work up, Recurrence, Treatment response assessment / Surveillance

Adult Intracranial and Spinal Ependymoma (exluding Subependymoma)

• Work up, Recurrence, Treatment response assessment / Surveillance

Adult Medulloblastoma and Supratentorial PNET (excluding esthesioneuroblastoma)

• Work up, Recurrence, Treatment response assessment / Surveillance

Primary CNS Lymphoma

• Evaluation

Primary Spinal Cord Tumours

• Recurrence, Surveillance

Limited (1-3) metastatic lesions

• Workup, Recurrence, Treatment response assessment / Surveillance

Multiple (>3) metastatic lesions

• Workup, Recurrence, Treatment response assessment / Surveillance

Metastatic Spine Tumours

• Work up
• For RT planning, as and when indicated, for the aforementioned tumours

• The non-oncological applications of Nuclear Medicine Imaging:

  Cardiac

  • Detection of CAD
  • Distinguishing between dysfunctional but viable myocardial tissue and scar.
  • Risk assessment
  • Inflammatory cardiac conditions

  CNS

  • Dementing disorders
  • Preoperative evaluation of partial epilepsy
  • Movement disorders.

  Inflammation and Infection {with 2-deoxy-2-(F-18)-fluoro-D-glucose (F-18 FDG)}

  • Sarcoidosis
  • Peripheral bone osteomyelitis (noncooperative, non-diabetic foot)
  • Suspected spinal infection (spondylodiscitis or vertebral osteomyelitis, noncooperative)
  • Evaluation of fever of unknown origin (including true FUO, postoperative fever and recurrent sepsis, immunodeficiency (both induced and acquired)-related FUO, neutropenic fever, and isolated acute-phase inflammation markers (persistently raised C-reactive protein and/or erythrocyte sedimentation rate)
  • Evaluation of metastatic infection and of high-risk patients with bacteremia.
  • Primary evaluation of vasculitis’s (ex. giant cell arteritis, etc.…)

  F18-Sodium Fluoride PET /CT Bone Scan

  1. To identify skeletal metastases, including localization and and determination of extent of disease.
  2. Back pain and otherwise unexplained bone pain
  3. Child abuse
  4. Abnormal radiographic or laboratory findings
  5. Osteomyelitis
  6. Trauma
  7. Inflammatory and Degenerative Arthritis
  8. Avascular Necrosis
  9. Osteonecrosis of the mandible
  10. Condylar hyperplasia
  11. Metabolic bone disease
  12. Paget’s disease
  13. Bone graft viability
  14. Complications of prosthetic joints
  15. Reflex sympathetic dystrophy.
  16. Distribution of osteoblastic activity prior to administration of therapeutic radiopharmaceuticals for treating bone pain.