*3.2.1. Registration*

Healthcare builds upon its performance with a wealth of innovations, from enabling low dosage and improved acquisition times to enhancing imaging results through scatter correc‐ tion modeling and reduction, motion detection and correction, and accurate attenuation correction. Hawkeye 4 should respond to all applications except exams angio CT or cardiology. PHILIPS approaches the market hybrid machines by combining existing methods in its range. The hybrid machine called PRECEDENCE. Precedence SPECT/CT system offers the combi‐ nation of functional data from SPECT with high-resolution anatomical detail from a multi-slice

18 Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

When SPECT functional data is fused with CT, the location and extent of disease may be better

SEIMENS "Symbia" SPECT-CT hybrid machine is integrated SPECT and diagnostic multislice-CT bring a whole new dimension to nuclear medicine. With the ability to provide precise localization of tumors and other pathologies before disease reveals itself, Symbia has the potential to revolutionize treatment planning for cancer, heart disease, and neurological disorders. Symbia has enormous potential for cardiac imaging, revealing even the hard-to-

> The Philips Precedence SPECT/CT scanner

Simultaneous PET and MRI scans eliminate the need to move patients from one imaging unit to another, making it easier to combine data from both scans to produce enhanced details. The scanner also exposes patients to significantly lower radiation levels than an older combined scanning technique, PET-computed tomography (CT). PET-MRI scanner is used in under‐ standing certain types of malignancies, such as cancers of the brain, neck and pelvis because the anatomy is very complex in those areas, and combined PET-MRI should produce a more detailed reading of the intricate boundaries between disease and healthy tissue. The integra‐ tion of PET and MRI for simultaneous scanning was a complex task because powerful MRI magnets interfered with the imaging detectors on the PET scanner. But scientists overcome this problem and PET-MRI scanners are nowadays available for research and patient care

The Siemens Symbia SPECT/CT scanner

diagnostic CT scanner to give clinicians a new standard of diagnostic confidence.

detect conditions that carry the highest risk for patients.

The GE Infinia Hawkeye 4 SPECT/CT scanner

**Figure 10.** Examples of SPECT-CT hybrid scanners.

*3.1.3. PET-MRI*

(Figure 11).

visualized and treated.

There is increasing interest in being able to automatically register medical images from either the same or different modalities. Registered images are proving useful in a range of applica‐ tions, not only providing more correlative information to aid in diagnosis, but also assisting with the planning and monitoring of therapy, both surgery and radiotherapy. The classifica‐ tion of registration methods is classically based on the criteria formulated by van den Elsen, Pol & and Viergever [31]. Many basic criteria can be used, which each can be developed and subdivided again [32, 33]. The main are the following:


opment and improving approaches for analysis and optimization of complex multi-compo‐ nent biomedical imaging devices is highly required. The validation methods are classified in

Principles and Applications of Nuclear Medical Imaging: A Survey on Recent Developments

http://dx.doi.org/10.5772/54884

21

To date there is very little in terms of validation and standardizing the validation process in nuclear image processing. Further research is needed in validation for nuclear image-proc‐ essing as issues concerning validation are numerous. Clinically relevant validation criteria need to be developed. Mathematical and statistical tools are required for quantitative evalua‐ tion or for estimating performances in the absence of a suitable reference standard. The diversity of problems and approaches in medical imaging contributes significantly to this. Validation data sets with available accuracy reference are required. Comprehension of clinical issues and establishment of robust therapy protocols is also required. Indeed, validation is by itself a research topic where methodological innovation and research are required [34].

**•** diagnose diseases such as cancer, neurological disorders (e.g., Alzheimer's and Parkinson's diseases), and cardiovascular disease in their initial stages through use of imaging devices

**•** provide molecularly targeted treatment of cancer, and certain endocrine disorders (includ‐

**•** Non-invasively assess a patient's response to therapies, reducing the patient's exposure to the toxicity of ineffective treatments, and allowing alternative treatments to be started

The use of nuclear hybrid imaging, particularly PET-CT, is expanding rapidly. More recently, positron emission tomography (PET) has increased its applications in total body imaging to include the postoperative orthopedic patient. PET and PET-CT scanning for postoperative infection has also been investigated in the spine, also showing good results, with increased specificity for infection in contrast to routine three-phase bone scan or combination radiotrac‐ ers [35]. The increasing specificity of nuclear medicine agents continues to broaden nuclear

The development of SPECT and SPECT-CT is a logical consequence of the previous success of PET-CT, the first of these hybrid imaging techniques. The introduction of this technique, about 10 years ago, meant a final advanced nuclear medicine in the field of oncology. Pushed forward by the scientific and commercial success of these PET-CT, the industry developed the SPECT-

medicine applications in the postoperative musculoskeletal imaging setting.

**4. Cases studies and future trends of nuclear imaging**

including PET-MRI, PET-CT and SPECT-CT;

ing thyroid disease and neuroendocrine tumors);

Current clinical applications of nuclear medicine include the ability to:

the following main categories:

**2.** Validation with phantoms;

**3.** Clinical validation.

earlier.

**1.** Statistical validation methods;


Although great advances have been made in basic nuclear medicine imaging in both the detection and estimation tasks, personalized medicine is a challenging goal. It requires the ability to detect many different signals that are specific to a patient's disease. That requirement has led to the increasing development of hybrid imaging systems.

The development of image reconstruction algorithms, simulation tools, and techniques for kinetic model analysis plays an important role in the right interpretation of the generated image signals. Development of these software tools is essential to accurately model the data and thereby quantify the radiotracer uptake in nuclear medicine studies. The ability to perform this task in practice has benefited from the increased availability of powerful computing resources. For example, an iterative image reconstruction algorithm with data corrections built into the system model was considered to be impractical a decade ago. Yet, this type of algorithm can now be used to generate images in a practical amount of time in both the research laboratory and the clinic Leaders in instrumentation and computational development in nuclear medicine from universities, national laboratories, and industry were solicited for commentary and analysis.

#### *3.2.2. Validation*

The ability of nuclear imaging devices to provide anatomical images and physiological information has provided unparalleled opportunities for biomedical and clinical research, and has the potential for important improvements in the diagnosis and treatment of a wide range of diseases. However, all nuclear imaging devices suffer from various limitations that can restrict their general applicability. Some major limitations are sensitivity, spatial resolution, temporal resolution, and ease of interpretation of data. To overcome these limitations, scientists have worked particularly on: on: 1) Development of technological and methodolog‐ ical advances that improve the sensitivity, spatial resolution and temporal resolution, 2) Development of multi-modality approaches that combine two (or more) biomedical imaging techniques. In addition to these two research areas, validation of nuclear imaging technologies and methodologies is uncontainable to develop nuclear imaging and medicine. Development of "multi-modality" approaches could be used to combine information that might not be available from a single imaging technique or to compare and validate results obtained with one imaging technique with results obtained using another imaging technique. Thus, devel‐ opment and improving approaches for analysis and optimization of complex multi-compo‐ nent biomedical imaging devices is highly required. The validation methods are classified in the following main categories:


**3.** Nature of transformation: rigid, affine, projective, or curved;

has led to the increasing development of hybrid imaging systems.

**6.** Optimization procedure: parameters computed or parameters searched for;

20 Imaging and Radioanalytical Techniques in Interdisciplinary Research - Fundamentals and Cutting Edge Applications

**7.** Modalities involved: mono-modal, multi-modals, modality to model or patient to

Although great advances have been made in basic nuclear medicine imaging in both the detection and estimation tasks, personalized medicine is a challenging goal. It requires the ability to detect many different signals that are specific to a patient's disease. That requirement

The development of image reconstruction algorithms, simulation tools, and techniques for kinetic model analysis plays an important role in the right interpretation of the generated image signals. Development of these software tools is essential to accurately model the data and thereby quantify the radiotracer uptake in nuclear medicine studies. The ability to perform this task in practice has benefited from the increased availability of powerful computing resources. For example, an iterative image reconstruction algorithm with data corrections built into the system model was considered to be impractical a decade ago. Yet, this type of algorithm can now be used to generate images in a practical amount of time in both the research laboratory and the clinic Leaders in instrumentation and computational development in nuclear medicine from universities, national laboratories, and industry were solicited for

The ability of nuclear imaging devices to provide anatomical images and physiological information has provided unparalleled opportunities for biomedical and clinical research, and has the potential for important improvements in the diagnosis and treatment of a wide range of diseases. However, all nuclear imaging devices suffer from various limitations that can restrict their general applicability. Some major limitations are sensitivity, spatial resolution, temporal resolution, and ease of interpretation of data. To overcome these limitations, scientists have worked particularly on: on: 1) Development of technological and methodolog‐ ical advances that improve the sensitivity, spatial resolution and temporal resolution, 2) Development of multi-modality approaches that combine two (or more) biomedical imaging techniques. In addition to these two research areas, validation of nuclear imaging technologies and methodologies is uncontainable to develop nuclear imaging and medicine. Development of "multi-modality" approaches could be used to combine information that might not be available from a single imaging technique or to compare and validate results obtained with one imaging technique with results obtained using another imaging technique. Thus, devel‐

**4.** Doman of transformation: local, global or interaction;

**5.** Interaction: interactive, semi-automatic or automatic;

**8.** Subject: intrasubject; intersubject or atlas;

**9.** Object: head, abdomen, limbs, thorax…

modality;

commentary and analysis.

*3.2.2. Validation*

To date there is very little in terms of validation and standardizing the validation process in nuclear image processing. Further research is needed in validation for nuclear image-proc‐ essing as issues concerning validation are numerous. Clinically relevant validation criteria need to be developed. Mathematical and statistical tools are required for quantitative evalua‐ tion or for estimating performances in the absence of a suitable reference standard. The diversity of problems and approaches in medical imaging contributes significantly to this. Validation data sets with available accuracy reference are required. Comprehension of clinical issues and establishment of robust therapy protocols is also required. Indeed, validation is by itself a research topic where methodological innovation and research are required [34].
