Nuclear Medicine Practice Questions

Q: All the following radioisotopes are used in painful body metastasis except

Yttrium. ***Yttrium*** - **Yttrium-90 (⁹⁰Y)** is a pure **beta-emitter** primarily used for **radioembolization of liver tumors** (selective internal radiation therapy) and **radiosynovectomy** for joint inflammation. - It is **NOT a standard radioisotope for treating painful bone metastases**, unlike the other options listed. - Its high-energy beta particles and specific applications make it unsuitable for the palliative treatment of bone pain from metastases. *Tin-117* - **Tin-117m (¹¹⁷ᵐSn-DTPA)** is a **conversion electron emitter** that has been studied and used for palliation of painful bone metastases. - It localizes to areas of increased osteoblastic activity and provides localized radiation therapy. - Though less commonly used than Samarium-153 or Strontium-89, it is still a therapeutic option for bone pain. *Samarium-153* - **Samarium-153 (¹⁵³Sm-EDTMP)** is a commonly used **beta-emitting radioisotope** for the treatment of painful bone metastases. - It selectively binds to areas of increased bone turnover, such as metastases, and its beta emissions provide **localized pain relief**. - FDA-approved and widely used for bone pain palliation. *Strontium-89* - **Strontium-89 (⁸⁹Sr)** is another highly effective **beta-emitting radioisotope** used for palliation of painful bone metastases. - It is a **calcium analog** and is preferentially incorporated into bone mineral at sites of increased osteoblastic activity. - FDA-approved and considered a gold standard for bone pain treatment.

Q: Radio-isotope of iodine used for thyroid tissue destruction:

I-131. ***I-131*** - **Iodine-131** is widely used in nuclear medicine for the **destruction of thyroid tissue** in conditions like hyperthyroidism (Graves' disease) and differentiated thyroid cancer due to its emission of both beta and gamma radiation. - The **beta particles** emitted by I-131 have a short tissue penetration range, allowing for localized destruction of thyroid cells while minimizing damage to surrounding tissues. *I-132* - **Iodine-132** has a very short half-life (2.3 hours) and a lower energy beta emission compared to I-131, making it less suitable for sustained tissue destruction. - It is not commonly used for thyroid ablation due to its **less favorable decay characteristics** for therapeutic applications. *I-123* - **Iodine-123** is primarily a **gamma emitter** with a half-life of 13.2 hours, making it ideal for diagnostic imaging of the thyroid (e.g., thyroid scans). - It delivers a low radiation dose and is not used for tissue destruction because it lacks the **destructive beta particle emission** required for therapeutic effects. *I-125* - **Iodine-125** is a gamma emitter with a longer half-life (59.4 days) and is predominantly used in brachytherapy for some cancers and occasionally for **diagnostic imaging and research**. - While it has limited therapeutic uses, its primary application is not for widespread thyroid tissue ablation due to its **different decay mode** compared to I-131.

Q: Gamma camera in Nuclear Medicine is used for –

Organ imaging. ***Organ imaging*** - A **gamma camera** is primarily used to detect gamma rays emitted from **radiopharmaceuticals** introduced into the body. - This detection allows for the creation of 2D images or 3D tomographic images (SPECT) of organ function and structure. *Measuring the radioactivity* - While radioactivity is measured by the gamma camera, its primary purpose is not just to quantify dps/Bq, but to create a **spatial distribution** of this radioactivity. - Dedicated **dosimeters** or **activity meters** are used for precise measurement of radioactivity. *RIA* - **Radioimmunoassay (RIA)** is a laboratory technique used to measure the concentration of substances (e.g., hormones, drugs) in a sample, not a function of the gamma camera. - RIA utilizes **radioactively labeled antibodies** and antigens but does not involve imaging the body. *Monitoring the surface contamination* - **Geiger counters** or specific contamination meters are used for monitoring surface contamination. - A gamma camera is designed for internal imaging and is not practical or optimized for detecting external surface contamination.

Q: MUGA scan is not useful in:

Regional wall perfusion. ***Regional wall perfusion*** - A MUGA scan assesses **ventricular function** through blood pool imaging, evaluating wall motion and ejection fraction. - It does not directly visualize or quantify myocardial perfusion, which is the flow of blood through the coronary arteries to the heart muscle. *Stroke volume* - A MUGA scan accurately measures **end-diastolic volume** and **end-systolic volume**, from which stroke volume (EDV – ESV) can be calculated. - This parameter directly reflects the amount of blood pumped out by the ventricle with each beat. *Left ventricular ejection fraction* - The MUGA scan is considered a gold standard for calculating **left ventricular ejection fraction** (LVEF), a key indicator of cardiac pump function. - It uses a count-based method from gated blood pool images to determine the percentage of blood ejected from the left ventricle. *Regional wall motion* - MUGA scans are highly effective in assessing **regional wall motion abnormalities**, identifying areas of **hypokinesis**, **akinesis**, or **dyskinesis**. - This is crucial for diagnosing and monitoring conditions like myocardial ischemia or infarction, and is a primary utility of the scan.

Q: Radioactive isotope of which of the following is used in bone scans?

Technetium. ***Technetium*** - **Technetium-99m** (**Tc-99m**) is the most commonly used radioisotope for **bone scans** due to its favorable decay characteristics and ability to be chelated with phosphates. - When injected, **Tc-99m**-labeled phosphates are incorporated into areas of **increased osteoblastic activity**, highlighting regions of bone remodeling, trauma, infection, or malignancy. *Iodine* - **Iodine radioisotopes** (e.g., **Iodine-123**, **Iodine-131**) are primarily used for imaging and treating **thyroid conditions** because the thyroid gland actively absorbs iodine. - They are not used in bone scans as iodine does not accumulate significantly in bone tissue. *Gallium* - **Gallium-67** (**Ga-67**) is used in scans for detecting **inflammation**, **infection**, and some **tumors**, particularly lymphomas. - While it can sometimes enhance in areas of bone infection, it is not the primary or preferred agent for general **bone scintigraphy**. *Phosphorus* - While **phosphate compounds** are used as carriers for the radioactive isotope in bone scans, elemental **phosphorus** itself is not used as a radioactive isotope for imaging. - The **phosphate** ligands are labeled with **Technetium-99m** to create the radiopharmaceutical.

Q: The thyroid scan shown below exhibits a pattern that is most consistent with which of the following disorders?

Hypersecreting adenoma. ***Hypersecreting adenoma*** - The image likely displays a 'hot' nodule (area of increased tracer uptake), which is characteristic of a **hypersecreting (toxic) adenoma**. These adenomas produce thyroid hormones autonomously. - The rest of the thyroid gland typically shows **suppressed uptake** due to inhibition of TSH secretion by the autonomously functioning nodule's hormone overproduction. *Papillary carcinoma of thyroid* - Papillary carcinoma usually appears as a **cold nodule** (decreased or absent uptake) on a thyroid scan because cancerous cells generally do not concentrate iodine as efficiently as normal thyroid tissue. - While it is the most common type of thyroid cancer, it is rarely associated with increased iodine uptake. *Graves' disease* - Graves' disease exhibits **diffuse, increased uptake** throughout the entire thyroid gland, reflecting generalized overactivity of thyroid follicular cells due to autoantibody stimulation. - The scan would show a uniformly active gland, not a focal hot spot with suppressed surrounding tissue. *Lateral aberrant thyroid* - This term typically refers to metastatic thyroid cancer (often papillary or follicular) in cervical lymph nodes, appearing as uptake outside the thyroid gland. - A lateral aberrant thyroid would not present as a focal hot nodule within the thyroid gland itself.

Q: What is a radionuclide scan finding in hyperparathyroidism?

Hot spots. ***Hot spots*** - **Hot spots** on a radionuclide scan in hyperparathyroidism indicate areas of **increased metabolic activity** or uptake of the radioactive tracer in the overactive parathyroid glands. - This increased uptake is due to the **overproduction of PTH** by the affected parathyroid glands, leading to their hyperplasia or adenoma. *Panda sign* - A **panda sign** is typically observed on a **gallium scan** or **PET scan** in sarcoidosis or other granulomatous diseases, indicating bilateral symmetric uptake in the parotid and lacrimal glands. - This finding is **not characteristic of hyperparathyroidism**, which involves parathyroid gland abnormalities. *Hawkin's sign* - **Hawkin's sign** is a radiologic finding on a plain X-ray, referring to subchondral lucency in the talar dome, indicating **avascular necrosis of the talus** after ankle fracture. - It is an orthopedic finding and has **no relevance to radionuclide scans** or hyperparathyroidism. *Cold spots* - **Cold spots** on a radionuclide scan indicate areas of **decreased or absent tracer uptake**, suggesting reduced metabolic activity or tissue damage. - While some pathologies can cause cold spots, **hyperfunctioning parathyroid glands** typically show increased, not decreased, uptake.

Q: All of the following radioisotopes are used as systemic radionuclides, EXCEPT:

Iridium-192. ***Iridium192*** - While a radioisotope, **Iridium-192** is predominantly used in **brachytherapy**, a form of internal radiation therapy where the source is placed directly within or next to the tumor. - It is not typically administered systemically to treat widespread disease. *Strontium89* - **Strontium-89** is a **beta-emitting radionuclide** that mimics calcium and is selectively taken up by areas of increased bone turnover, such as **bone metastases** [1], [2]. - It is used systemically for palliative treatment of **pain from bone metastases** [1], [2]. *Samarium153* - **Samarium-153** is another **beta-emitting radionuclide** that targets bone metastases, similar to Strontium-89 [2]. - It is also administered systemically for **pain palliation** in patients with disseminated bone cancer [2]. *Phosphorus32* - **Phosphorus-32** is a **beta-emitter** used systemically for the treatment of **polycythemia vera** (a myeloproliferative disorder) and **bone metastases** [1]. - It accumulates in areas of rapid cell proliferation, making it effective in these systemic treatments [1].

Q: All isotopes are used for thyroid except:

I-122. ***I-122*** - **Iodine-122** has an extremely short half-life (around 3.6 minutes) making its clinical utility for most thyroid procedures, which require longer imaging windows or therapeutic effects, impractical. - Due to its short half-life and positron emission, it is primarily used in **positron emission tomography (PET)** imaging, but not routinely for thyroid scans or therapy. *I-131* - **Iodine-131** is widely used in nuclear medicine for both the diagnosis (imaging) and treatment of thyroid diseases, particularly **hyperthyroidism** and **differentiated thyroid cancer**, due to its beta and gamma emissions. - Its relatively long half-life (8 days) allows time for uptake and accumulation in thyroid tissue, making it effective for therapy. *I-123* - **Iodine-123** is an ideal radionuclide for diagnostic thyroid imaging and uptake studies because it emits **gamma rays** suitable for SPECT imaging and has no particulate radiation (beta particles), minimizing patient radiation dose. - Its half-life of 13.2 hours is sufficient for obtaining high-quality images and physiological data. *All of the options* - This option is incorrect because **Iodine-131** and **Iodine-123** are commonly used in various thyroid diagnostic and therapeutic applications. - While Iodine-122 has limited practical use, the statement "All of the options" would imply none are used, which is false.

Q: Which technetium is most commonly used in bone pathology?

99mTc-MDP. ***99mTc-MDP*** - **Technetium-99m Methylene Diphosphonate (99mTc-MDP)** is the agent of choice for routine **bone scintigraphy** due to its optimal pharmacokinetics and high affinity for bone. - It readily binds to the **hydroxyapatite crystals** of bone, especially in areas of increased osteoblastic activity, making it excellent for detecting bone metastases, fractures, and infections. *99mTc-Sestamibi* - **Technetium-99m Sestamibi (99mTc-Sestamibi)** is primarily used for **myocardial perfusion imaging** to assess cardiac function. - It also has applications in parathyroid imaging for detecting **parathyroid adenomas**, but not for general bone pathology. *99mTc-Pyrophosphate* - **Technetium-99m Pyrophosphate (99mTc-Pyrophosphate)** was an older bone-seeking agent but has largely been replaced by MDP due to MDP's superior imaging characteristics. - Its main current use is in diagnosing **cardiac amyloidosis**, not for routine bone scans. *99mTc-Exametazime* - **Technetium-99m Exametazime (99mTc-Exametazime)**, also known as HMPAO, is specifically used for **leukocyte imaging** to detect infection and inflammation. - It is also used for **brain perfusion imaging** to assess cerebral blood flow, not for direct visualization of bone pathology.

Question 1

All the following radioisotopes are used in painful body metastasis except

Accepted Answer

Yttrium

Answer

Tin-117

Answer

Samarium-153

Answer

Strontium-89

Question 2

Radio-isotope of iodine used for thyroid tissue destruction:

Accepted Answer

I-131

Answer

I-132

Answer

I-123

Answer

I-125

Question 3

Gamma camera in Nuclear Medicine is used for –

Accepted Answer

Organ imaging

Answer

Measuring the radioactivity

Answer

RIA

Answer

Monitoring the surface contamination

Question 4

MUGA scan is not useful in:

Accepted Answer

Regional wall perfusion

Answer

Stroke volume

Answer

Left ventricular ejection fraction

Answer

Regional wall motion

Question 5

Radioactive isotope of which of the following is used in bone scans?

Accepted Answer

Technetium

Answer

Iodine

Answer

Gallium

Answer

Phosphorus

Question 6

The thyroid scan shown below exhibits a pattern that is most consistent with which of the following disorders?

Accepted Answer

Hypersecreting adenoma

Answer

Papillary carcinoma of thyroid

Answer

Graves' disease

Answer

Lateral aberrant thyroid

Question 7

What is a radionuclide scan finding in hyperparathyroidism?

Accepted Answer

Hot spots

Answer

Panda sign

Answer

Hawkin's sign

Answer

Cold spots

Question 8

All of the following radioisotopes are used as systemic radionuclides, EXCEPT:

Accepted Answer

Iridium-192

Answer

Strontium-89

Answer

Samarium-153

Answer

Phosphorus32

Question 9

All isotopes are used for thyroid except:

Accepted Answer

I-122

Answer

I-131

Answer

I-123

Answer

All of the options

Question 10

Which technetium is most commonly used in bone pathology?

Accepted Answer

99mTc-MDP

Answer

99mTc-Sestamibi

Answer

99mTc-Pyrophosphate

Answer

99mTc-Exametazime

Nuclear Medicine — MCQs

Nuclear Medicine — MCQs

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