**Abstract**

Nuclear medicine techniques have a great deal of advantage of using gamma radiation emitter radiolabeled compounds to diagnose the long list of infectious and malignant disorders in human systems. The gamma emitter radionuclide-labeled compounds are associated with single photon emission computed tomography (SPECT) camera. SPECT camera mainly offers the detection and analysis of gamma rays origin to furnish the imaging of defective organs in the body. There are about 85% radiopharmaceuticals in clinical practice which are being detected by SPECT camera. The following chapter is an update about the SPECT radiopharmaceuticals that were developed and tried for infection and cancer diagnosis.

**Keywords:** 99mTc-antibiotics, SPECT imaging, radiopharmaceuticals, nuclear medicines, infection imaging

#### **1. Introduction**

Nuclear medicine technique (NMT) is a detection process that helps in obtaining diagnostic results at molecular level of a disease. The technique is carried out by administrating target-specific radioisotope-labeled organic/biomolecule to patient and collecting the gamma signals through scintillating camera to diagnose the infected organ/tissues. In contrast to advanced instrumental procedures such as magnetic resonance imaging (MRI) and computed tomography (CT) scan, NMT offers a wide range of detection limit. For example, NMT starts working from molecular level when no morphological changes appear; however MRI and CT do this job at the appearance of morphological changes in diseased tissues.

NMT works by administration of radiolabeled molecules (commonly known as radiopharmaceuticals) to patients and acquisition of radiation collected through scintillation camera. There are two main components of radiopharmaceuticals: the organic/biomolecule and the radioisotope. The former approaches diseased cells/ tissues and accumulate there at diseased cells and the latter part emits radiation to indicate the position of diseased area.

Diagnosis through NMT means the image of internal body organs like heart, kidney, lungs, breast, brain, bones, tissues, or whole body using γ-emitting radiopharmaceuticals; for example, indium-111 (111In) and technetium-99m (99mTc) labeled molecules. These radionuclides are labeled with a variety of compounds including drugs, organic species, peptides, proteins, and antibodies and then


Effectiveness of the radiopharmaceutical depends upon both parts. In order to prepare a good and efficient radiopharmaceutical, the first step involves the selection of a pharmaceutical component which is very critical [3]. Pharmaceuticals that have a preferable accumulation in targeted body organ, tissues, or cells should be selected. After the selection of pharmaceutical component, pharmaceutical is labeled with a suitable radiotracer. The radiopharmaceutical is subjected to administration after a routine quality control procedure. There are many disease targeted radiolabeled agents or compounds that are commonly used for diagnosis and therapeutic purpose. From diagnostic point of view, disease-targeted agents (either a drug or any other compound) are labeled with γ-emitting radiotracer, and for therapeutic purpose, these agents are labeled with β and α radiotracer like lutetium-177 (177Lu) and Yatrium-90 (90Y) [4]. In **Table 2**, some of the disease-targeted agents (radiopharmaceuticals) are shown which are used for diagnostic imaging

**Targeted agent with labeled radiotracer Emitting radiation Cancer type/disease** Metastron (89SrCl2) β-emitting Skeletal cancer

*Single-Photon Emission Computed Tomography (SPECT) Radiopharmaceuticals*

Radium-223 dichloride α-emitting Bone metastasis, breast and

Samarium-153-EDTMP β-emitting Bone and prostate cancer

prostate cancer

Radiopharmaceuticals which are used to diagnose the cancer and infection by using the γ-emitting radionuclides such as 111In and 99mTc are known as SPECT radiopharmaceuticals. The radiotracer which is used for diagnostic purposes should

**γ-emitting radiotracer Half-life (hours) Generator Gamma energy Abundance of**

Technetium-99m 6.02 99mMo/99mTc 140 keV 88.9 Iodine-123 13.22 Cyclotron 159 keV 82.8

**γ-emission (%age)**

90.5 94

0.245 MeV

and therapeutic purpose of different diseases and cancers.

*Commonly used radiopharmaceuticals for therapeutic purpose [4].*

*DOI: http://dx.doi.org/10.5772/intechopen.93449*

• Easy availability at nuclear medicine center

• Short effective half-life then labeled pharmaceutical

Indium-111 67.32 Cyclotron 0.l7l MeV

**3. SPECT—radiopharmaceuticals**

have following properties [5]:

*Common properties of γ-emitting radionuclides.*

• Low cost

**Table 2.**

• Carrier free

• Nontoxic

**Table 3.**

**5**

## **Table 1.**

*Gamma-emitting radiotracer for diagnostic imaging of different types of cancer and infection [1].*

injected into the patient's body. Intravenously administrated radiopharmaceuticals accumulate in specific body part or organ for which it is prepared and scans are obtained by single photon emission computed tomography (SPECT) camera [1]. Scan generated by SPECT camera gives very fruitful information regarding disease and tumor, which makes it easier for doctors to make decision about treatment strategies.

A large number of compounds have been labeled with γ-emitting radiotracers for imaging of different types of cancer and infection. Some of them are shown in **Table 1** below [2].
