**12. Indirect method labeling using bi-functional chelating agent**

A chelating agent is a substance that has the ability to form multiple bonds with a single metal ion, thus acts as a multidendate ligand. Bi-functional chelating agent is that which has two are more separate covalent or coordinate covalent bonds with a ligand which is polydendate in nature. The labeling process using bi-functional chelating agent involves the bond formation at two sites: one bond is formed by the bi-functional chelating agent with macromolecule such as protein and antibody and other bond is formed with metal ion such as Tc-99m. There are many bi-functional chelating agents being used currently; however, most important are diethylenetriamine pentaacetic acid (DTPA), metallothionein, diamide dimercaptide (N2S2), dithiosemicarbazone, and hydrazinonicotinamide.

There are two types of labeling process by using bi-functional chelating agent.

(a) Tc-99m chelate method: In this method, a chemical is used to carry out chelation (such as diamidodithiol and cyclam) and labeling of macromolecules such as protein by forming the bond between chelating agent and protein (macromolecule).

(b) Indirect chelater antibody method: In this method, bi-functional chelating agent forms a bond with macromolecule and then it reacts with metal ion to form the complex known as metal-chelator-macromolecule complex. By using indirect chelator antibody method, a number of antibodies are labeled. The biological function of the antibodies may be affected due to the presence of the chelating agent; therefore, it is necessary to check the labeling products before a clinical trial. It is no doubt that the prelabeled chelating method gives pure metal-chelate- complex with precise structural study. However, the main drawback of this method is that it is a lengthy procedure and gives poor yield [17].

These SPECT-radiopharmaceuticals can also be developed for early and accurate diagnosis of cancer in different body parts and organs. A variety of drugs and compounds such as peptides, proteins, antibodies, and organic species were labeled with radionuclides such as indium-111 and technetium-99m, and these radiolabeled compounds are used for the successful and accurate diagnosis of different types of cancer in human and mice models [18]. In **Table 8**, a number of compounds which

are labeled with γ-emitting radiotracer for SPECT imaging of different types of

**SPECT imaging model**

15. HMPAO 99mTc Mice model Neuroblastoma 88% [12] 16. Oxine 111In Mice model Neuroblastoma 80% [12]

model

18. TDMPP complex 111In Mice model Tumor imaging [14]

model

**Pathology Sensitivity/**

Sentinel lymph node Radiolabeled

**Pathology Sensitivity/**

Neuroendocrine tumors 95% [16]

Bone imaging [16]

Inflammation imaging [16]

Inflammation imaging [16]

Breast cancer and melanomas

Breast cancer, head/neck malignancies, prostate cancer and gynecological malignancies

Biochemical disease-free survival and diseasespecific survival in primary prostate cancer

**accuracy**

Well accepted [16]

46% [16]

**Refs.**

[16]

Tumor imaging 9.39% ID/g [15]

receptor tumors: evaluation

**accuracy**

5.8 9.6% ID/g

98.5 0.5%

**Refs.**

[11]

[13]

used to identify the effects of previous treatment strategy, for example,

**SPECT imaging model**

model

model

model

model

model

model

model

111In Human

99mTc Human

testinal tract, lungs, pancreas, and rest of the body (**Table 9**).

**Labeled radioisotope**

1 Nano-colloids 99mTc Human

2 Radio-colloid 99mTc Human

3 Pentetreotide 111In Human

4 Capromab 111In Human

5 Medronate 99mTc Human

6 Labeled white blood cells

7 Labeled white blood Cells

**15**

SPECT-radiopharmaceuticals are not only used to identify infections and malignancies but are equally used to know the effectiveness of the treatment strategy which is used to cure the infections and tumors. That means, we can employ the SPECT-radiopharmaceuticals for follow-up strategy to know about the effectiveness of a treatment methods. A large numbers of radiolabeled compounds are being

pentetreotide is labeled with indium-111 to follow-up of the neuroendocrine tumor therapy (tumor generated due to the hormonal cell and nerves system) in gastroin-

cancer with accuracy are shown.

17. Rhenium sulfide colloidal nanoparticles

19. DOTA conjugate - TA138

**Labeled compound Labeled**

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

**radioisotope**

14. HYNIC-TOC 99mTc Mice model Somatostatin-

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

99mTc Rabbit

111In Mouse

*SPECT-radiopharmaceuticals using Tc-99m and In-111 for cancer imaging.*

**Sr. no.**

**Table 8.**

**Sr no.**

**Labeled compound**


*Single-Photon Emission Computed Tomography (SPECT) Radiopharmaceuticals DOI: http://dx.doi.org/10.5772/intechopen.93449*


#### **Table 8.**

other bond is formed with metal ion such as Tc-99m. There are many bi-functional chelating agents being used currently; however, most important are diethylenetriamine pentaacetic acid (DTPA), metallothionein, diamide dimercaptide (N2S2),

There are two types of labeling process by using bi-functional chelating agent. (a) Tc-99m chelate method: In this method, a chemical is used to carry out chelation (such as diamidodithiol and cyclam) and labeling of macromolecules such as protein by forming the bond between chelating agent and protein (macromolecule). (b) Indirect chelater antibody method: In this method, bi-functional chelating agent forms a bond with macromolecule and then it reacts with metal ion to form the complex known as metal-chelator-macromolecule complex. By using indirect chelator antibody method, a number of antibodies are labeled. The biological function of the antibodies may be affected due to the presence of the chelating agent; therefore, it is necessary to check the labeling products before a clinical trial. It is no doubt that the prelabeled chelating method gives pure metal-chelate- complex with precise structural study. However, the main drawback of this method is that it is a

These SPECT-radiopharmaceuticals can also be developed for early and accurate

diagnosis of cancer in different body parts and organs. A variety of drugs and compounds such as peptides, proteins, antibodies, and organic species were labeled with radionuclides such as indium-111 and technetium-99m, and these radiolabeled compounds are used for the successful and accurate diagnosis of different types of cancer in human and mice models [18]. In **Table 8**, a number of compounds which

> **SPECT imaging model**

> > model

model

model

model

model

9. (Arg11)CCMSH 99mTc Mice model Murine melanoma 3.33 0.50%

11. DTPA-octreotide 111In Mice model Lung cancer Bm/B was

13. DTPA-octreotide 111In Mice model Somatostatin-

model

5. DTPA-AMB8LK 111In Mice model Pancreatic cancer 23.6 3.9%

111In Human

**Pathology Sensitivity/**

Metastatic prostate cancer

Neuroendocrine tumor (NETs)

111In Mice model Murine melanoma 8.19 1.63%

Metastatic neuroendocrine tumors

receptor tumors: evaluation

Parathyroid adenoma Range from

Bone metastases Very

Tumor target [6]

**accuracy**

ID/g

85 to 95%

sensitive

ID/g

ID/g

3.1 0.6

Sensitivity 87%

4.3%ID/g [11]

95% [8]

**Refs.**

[6]

[7]

[8]

[8]

[9]

[9]

[19]

[10]

dithiosemicarbazone, and hydrazinonicotinamide.

lengthy procedure and gives poor yield [17].

**Labeled compound Labeled**

2. HYNIC-Glu-Urea 99mTc Human

6. Octreotide 111In Human

7. Sestamibi 99mTc Human

8. MDP 99mTc Human

12. HYNIC-TOC 99mTc Human

**radioisotope**

**Sr. no.**

*Medical Isotopes*

1. Anti-PSMA nanobody

10. DOTA-Re(Arg11) CCMSH

**14**

*SPECT-radiopharmaceuticals using Tc-99m and In-111 for cancer imaging.*

are labeled with γ-emitting radiotracer for SPECT imaging of different types of cancer with accuracy are shown.

SPECT-radiopharmaceuticals are not only used to identify infections and malignancies but are equally used to know the effectiveness of the treatment strategy which is used to cure the infections and tumors. That means, we can employ the SPECT-radiopharmaceuticals for follow-up strategy to know about the effectiveness of a treatment methods. A large numbers of radiolabeled compounds are being used to identify the effects of previous treatment strategy, for example,

pentetreotide is labeled with indium-111 to follow-up of the neuroendocrine tumor therapy (tumor generated due to the hormonal cell and nerves system) in gastrointestinal tract, lungs, pancreas, and rest of the body (**Table 9**).



**Sr no.**

**Labeled compound**

3. EDDA/HYNIC-TOC

6. labeled leukocyte

**Labeled radioisotope**

1. HMPAO 99mTc Human

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

2. Tropolonate 111In Human

4. P829 peptide 99mTc Human

5. Pentetreotide 111In Human

7. HYNIC-TOC 99mTc Human

8. HYNIC-OC 99mTc Human

9. HYNIC-TOC 99mTc Human

10. HYNIC-TATE 99mTc Human

11. DTPA-OC 111In Human

12. DOTA-TATE 111In Human

13. Depreotide 99mTc Human

14. DTPA 99mTc Human

15. HDP 99mTc Human

16. Tetrofosmin 99mTc Human

17. ECD 99mTc Human

18. MAA 99mTc Human

19. Mebrofenin 99mTc Human

20. HSA-DTPA 99mTc Human

21. GHA 99mTc Human

22. MDP 99mTc Human

23. DMSA 99mTc Human

**17**

**SPECT imaging model**

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

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

99mTc Human

111In Human

**Pathology Sensitivity/**

Painful prosthetic hip 39% (SD 12%) [20]

Painful prosthetic hip 63% (SD 14%) [20]

Neuroendocrine tumors 91% [22]

Neuroendocrine tumors 65% [22]

Metastatic neuroendocrine tumors

> Glioblastoma multiforme

Hepatobiliary Scintigraphy

Gastrointestinal bleeding

Osteomyelitis 91% [23]

Tumor 0.70 0.13%ID/g [24]

Malignancies 3.85 1.0 [24]

Tumor 3.99 0.58%ID/g [24]

Tumor 0.99 0.08%ID/g [24]

Tumor 4.12 0.74%ID/g [24]

Graves' disease Specificity 89% [29]

Bone imaging [30]

Alzheimer's patients [32]

Liver perfusion imaging 100% [33–

Brain-scanning 85% [37]

Cerebral infarction [38]

Acute pyelonephritis [39]

histochemical correlations 98%

L/N ratio of 4.7 [31]

[25– 28]

35]

[36]

70% [34]

Lung cancer Immuno-

Cancer diagnosis High tumor to

**accuracy/ efficiency**

organ ratio

Sensitivity 87% [10]

**Refs.**

[21]

**Table 9.**

*SPECT-radiopharmaceuticals using Tc-99m and In-111 for follow-up imaging.*

*Single-Photon Emission Computed Tomography (SPECT) Radiopharmaceuticals DOI: http://dx.doi.org/10.5772/intechopen.93449*


**Sr no.**

*Medical Isotopes*

**Labeled compound**

11 His-annexin A5 C2AcH-

12 (Me) FGCDEVD

13 DTPA-Ac-TZ14011

15 DTPA-Fab-PEG24-EGF

19 DPAalendronate

20 human umbilical tissue-derived cells

23 nanobody (Nb cl1) against CD206 radiolabeled

25 99mTcmeropenem

26 99mTcnitroimidazole

**Table 9.**

**16**

**Labeled radioisotope**

8 Maraciclatide 99mTc Human

**SPECT imaging model**

model

9 3P-RGD2 99mTc [16] 10 MSAP-RGD 111In [1]

111In Chemokine receptor 3

14 AMD3100 99mTc [1]

111In Epidermal growth factor

16 Etarfolatide 99mTc Folate receptor [1] 17 DOTA-folate 111In [1]

18 MIP1404 99mTc Prostate-specific

111In Mice

21 99mTc-pHLIP Mice

22 99mTc-HHK Rat

24 99mTc-PyDA Mice

model

model

model

model

model

Mice Differentiate from

inflamed and infected tissues

cells

99mTc Mice

27 99mTc-SD32 Breast tumor

*SPECT-radiopharmaceuticals using Tc-99m and In-111 for follow-up imaging.*

99mTc(CO)3 Apoptosis [2]

99mTc [16]

expression

receptor

membrane antigen

99mTc(CO)3 Bone imaging [1]

Lewis lung carcinoma (LLC), lymph node carcinoma of the prostate (LNCaP) and prostate adenocarcinoma

Cerebral ischemia [17]

Tumor microenvironment High specificity [18]

Macrophages in tumor [18]

In vivo hypoxia targeting Selective uptake [18]

Tumor hypoxia tissue [18]

adequate imageability and correlation with tumor extracellular acidity

**Pathology Sensitivity/**

Angiogenesis [16]

**accuracy**

**Refs.**

[1]

[1]

[1]

[18]

[18]

[18]


A number of SPECT-radiopharmaceuticals are being used in clinical trials which are producing very fruitful results for the diagnosis of different types of cancers and infections in human beings (**Table 10**). These radiolabeled compounds help doctors obtain useful and precise information at a very early stage of the disease to identify the extent of problem and to take timely decisions about the treatment strategies.

There is a need to develop more accurate, sensitive, precise, and reliable SPECTradiopharmaceuticals to identify the malignant infections and tumors at an early stage in order to overcome the infectious diseases and cancer all over the world. If cancer is diagnosed at an early stage, it would be easier to plan the exact treatment strategy ahead of time. Considerable advancements have been made during last decades in SPECT-radiopharmaceuticals that may take the place of instrumental imaging techniques and therapeutic strategies. In combination with existing technologies, NMT may help a lot in the diagnostic and therapeutic advancement of

\* and Muhammad Babar Imran<sup>2</sup>

2 Punjab Institute of Nuclear Medicine (PINM), Faisalabad, Pakistan

\*Address all correspondence to: draliraza@gcuf.edu.pk

provided the original work is properly cited.

1 Department of Chemistry, Government College University, Faisalabad, Pakistan

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

**Future prospect**

**Sr no.**

**Table 10.**

**Labeled compound**

**Labeled radioisotope**

44. Annexin-V 99mTc Human

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

45. Neuroligands 99mTc Human

46. EC-MN 99mTc Human

*Clinical trials study of different SPECT radiopharmaceuticals.*

**SPECT imaging model**

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

model

model

model

**Pathology Sensitivity/**

Hypoxia [4]

Acute myocardial infarction and chemotherapy response monitoring

> Neuropsychiatric patients

**accuracy/ efficiency** **Refs.**

[4]

[4]

clinical detection methods.

**Author details**

**19**

Syed Ali Raza Naqvi<sup>1</sup>

*Single-Photon Emission Computed Tomography (SPECT) Radiopharmaceuticals DOI: http://dx.doi.org/10.5772/intechopen.93449*


**Table 10.**

**Sr no.**

*Medical Isotopes*

**Labeled compound**

25. Sulfur Nanocolloid

26. Oxine-labeled leukocytes

27. HMPAO-labeled leukocyte

28. MAA-and HAS Microspheres

30. Labeled bone marrow mesenchymal stem cells

33. Sulfur Nanocolloid

34. HMPAO-labeled leukocyte

36. Labeled GnRH-I tracer

37. Oxine labeled mesenchymal stem cells

**18**

35. Labeled chimeric monoclonal antibody Nd2

**Labeled radioisotope**

24. Pyrophosphate 99mTc Human

29. HSA-DTPA 99mTc Human

31. Oxine 111In Human

32. HMPAO 99mTc Human

38. TRODAT-1 99mTc Human

39. Depreotide 99mTc Human

40. Prostascint 99mTc Human

41. Zevalin 111In Human

42. CEA scan 99mTc Human

43. Depreotide 99mTc Human

Octreo Scan 111In Human

**SPECT imaging model**

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

model

99mTc Human

111In Human

Tc-99m Human

99mTc Human

111In Human

99mTc Human

99mTc Human

111In Human

111In Human

111In Human

**Pathology Sensitivity/**

Liver cysts 87.5%

Lymphatic drainage from prostate

> Gastrointestinal bleeding

Acute brain trauma model

Mapping of lymphatic drainage from the prostate

> Prosthetic joint infections

Lung cancer and other pulmonary malignancies

Diagnosis of non-Hodgkin's lymphoma

Amyloidoses 97% [40]

Abscess [42]

Liver-lung shunt [35]

Diagnostic imaging 80% [42]

Diagnostic imaging 88% [42]

Pancreatic cancer 100% [44]

Cirrhosis [46]

Prostate cancer Approved [4]

Colon cancer Approved [4]

Lung cancer [4]

Neuroendocrine tumors [4]

11.8 1.9%

synaptic dopamine transporter (DAT)

96.6% [4]

Approved for use [4]

Tumor imaging Efficiency

Parkinson disease Target the pre-

**accuracy/ efficiency**

3.9–5.2 mSv/MBq [41]

100% [34]

[43]

[41]

[45]

[47]

91% [5]

**Refs.**

*Clinical trials study of different SPECT radiopharmaceuticals.*

A number of SPECT-radiopharmaceuticals are being used in clinical trials which are producing very fruitful results for the diagnosis of different types of cancers and infections in human beings (**Table 10**). These radiolabeled compounds help doctors obtain useful and precise information at a very early stage of the disease to identify the extent of problem and to take timely decisions about the treatment strategies.
