Hybrid Imaging by SPECT/CT and PET/CT: Proven Outcomes in Cancer Imaging
Section snippets
Positron Emission Tomography/X-ray Computed Tomography
The essential prerequisite for PET/CT investigation is a PET indication. (The CT part of the investigation may be adapted, the indication of a stand-alone CT investigation.) Therefore, we refrain from repeating all possible PET indications, which are essentially the same in PET/CT.
Usually, oncologic positron emission tomography (PET) uses the radioactively labeled glucose analog 18F-fluorodeoxyglucose (FDG). The investigation is based on the principles discovered by Warburg et al2 that tumors
Methods
PET and CT are well-established diagnostic procedures. PET focuses on biochemical characteristics of diseases and may afford poor special resolution, whereas CT mostly relies on imaging morphology and structure and needs to have a very high spatial resolution. Thus, the combination of the 2 is very promising, especially with regard to synergistic effects. The advantage is exclusively on the side of PET. The high quality CT image is quickly acquired and can be used for attenuation correction of
Methodological Problems
Using CT data for attenuation correction for PET as performed in PET/CT will automatically lead to an impairment of PET images by artifacts already present in CT. However, the probability and the extent of artifacts caused by spatial and temporal misalignment of the PET and the CT image depend on the applied protocols and the thoroughness of their performance.
Local misregistration between the CT and the PET in integrated PET/CT or the use of CT contrast media may lead to artifacts in
Impact of PET/CT in Oncologic Staging and Restaging
In a review reflecting the improvements in cancer staging with FDG-PET/CT, Czernin et al26 concluded that improvements in the staging and restaging accuracies of FDG-PET/CT over FDG-PET or CT alone for different cancers have now been established. These improvements are frequently statistically significant and average about 10%-15%. Patients with cancers of the head and neck, thyroid, breast, lung, and gastrointestinal tract; cancer of unknown primary; lymphoma; and melanoma especially benefit
Application of Tracers Beyond FDG
Parallel to the development of, and probably stimulated by, PET/CT, there has been a diversification of the application of positron emitter labeled radiopharmaceuticals. Past and ongoing radiopharmaceutical developments led to numerous PET tracers beyond FDG. Regardless of tracer, PET/CT proves to be of special value—compared to PET alone—both for tracers that show highly specific accumulation and for tracers that, by contrast, show a low specific accumulation with an inhomogeneous background
Single-Photon Emission Computed Tomography/X-ray Computed Tomography
The advantages of PET/CT hybrid imaging described in the previous section of this article should also hold true for cameras integrating SPECT and CT. Therefore, in 2000, SPECT/CT hybrid cameras were introduced in the market, integrating a two-headed state-of-the-art SPECT camera with a nonspiral low-dose CT scanner.44, 45 The CT images from these cameras are of nondiagnostic quality; nevertheless, they allow a fairly accurate localization of foci of pathologic tracer uptake and attenuation
Miscellaneous Tumor Imaging Procedures
123I-meta-iodobenzylguanidine accumulates in cells via the action of the reuptake transporter for norepinephrine. This protein is expressed in a minority of neuroendocrine carcinomas, benign and malignant pheochromocytomas, and neuroblastoma, a malignant tumor affecting children.48, 79 Studies have highlighted the potential of SPECT/CT for this tracer also, similar to what has been published for 131I- and somatostatin receptor-SPECT (Fig. 8).80, 81, 82, 83 Here again, hybrid imaging combining
Sentinel Lymph Node Scintigraphy
Sequential scintigraphy performed after intra- or peritumoral injection of 99mTc-labeled colloids allows the identification of the first lymph node draining a tumor, ie, the sentinel lymph node (SLN). After its removal by radio-guided surgery, it is examined histopathologically. If it does not harbor tumor cells, lymphatic tumor spread is highly unlikely, and the patient can be spared the lymphatic basin dissection frequently associated with severe lifelong side effects such as lymphedema and
Use of SPECT/CT for Dosimetry of Molecular Radiotherapy
SPECT suffers from attenuation artifacts.114 These lead to considerable inaccuracies in the quantification of the concentration of therapeutic radiopharmaceuticals in neoplastic foci. Therefore, SPECT is as yet rarely used for dosimetry of molecular radiotherapy. CT-based attenuation correction of SPECT has now become possible. First data show that it is quantitatively exact for tracers labeled with 99mTc or 111In115, 116, 117; data for its performance for 131I are still missing.
Studies using
Conclusion
The last decade has seen the introduction of PET/CT and SPECT/CT as the first techniques capable of simultaneously acquiring information on the structural and molecular alterations caused by disease. Soon after development of these techniques, a wealth of data on the superior diagnostic value of these hybrid imaging technologies was collected and published, particularly in oncology.
PET/CT has already made stand-alone PET obsolete. The authors expect a similar development to occur in the field
Acknowledgments
Professor Kuwert lectures on behalf of Siemens Medical Solutions. From 2005 to 2007, his institution was lent a SPECT/spiral-CT system by this company. Dr Schmidt and Professor Kuwert acknowledge helpful discussions with PD Dr Rainer Linke from the Clinic of Nuclear Medicine in Erlangen. They are deeply indebted to the late Professor Werner Bautz, without whose continuous and generous support correlative imaging in Erlangen would not have been possible.
References (120)
- et al.
Software for image registration: Algorithms, accuracy, efficacy
Semin Nucl Med
(2003) - et al.
Presurgical staging of non–small-cell lung cancer: PET and PET/CT in NSCLC positron emission tomography, integrated positron emission tomography/CT, and software image fusion
Chest
(2005) - et al.
Positron emission tomography and positron emission tomography/computerized tomography of urological malignancies: An update review
J Urol
(2008) - et al.
Single-photon emission computed tomography/computed tomography: Basic instrumentation and innovations
Semin Nucl Med
(2006) - et al.
SPECT/CT in tumor imaging: Technical aspects and clinical applications
Semin Nucl Med
(2003) - et al.
Single-photon emission computed tomography/computed tomography in endocrinology
Semin Nucl Med
(2006) Single-photon emission computed tomography/computed tomography in lung cancer and malignant lymphoma
Semin Nucl Med
(2006)- et al.
The role of single-photon emission computed tomography/computed tomography in benign and malignant bone disease
Semin Nucl Med
(2006) - et al.
Single-photon emission computed tomography/computed tomography for sentinel node mapping in breast cancer
Semin Nucl Med
(2007) - et al.
Single-photon emission computed tomography/computed tomography in brain tumors
Semin Nucl Med
(2007)
Evidence against the use of lumbar spine radiography for low back pain
Clin Radiol
Artifacts, anatomical and physiological variants, and unrelated diseases that might cause false-positive whole-body I-131 scans in patients with thyroid cancer
Semin Nucl Med
Somatostatin receptor imaging
Semin Nucl Med
Imaging of neuroendocrine tumors
Semin Nucl Med
The clinical impact of a combined gamma camera/CT imaging system on somatostatin receptor imaging of neuroendocrine tumors
Clin Radiol
Clinical utility of fused 67Ga SPECT/CT scan images in patients with lymphoma
Rev Esp Med Nucl
Lymph node imaging: Basic principles
Eur J Radiol
Dynamic lymphoscintigraphy and image fusion of SPECT and pelvic CT-scans allow mapping of aberrant pelvic sentinel lymph nodes in malignant melanoma
Eur J Cancer
Multimodal image registration for localization of sentinel nodes in head and neck squamous cell carcinoma
J Oral Maxillofac Surg
Hybrid SPECT-CT: An additional technique for sentinel node detection of patients with invasive bladder cancer
Eur Urol
A combined PET/CT scanner: The path to true image fusion
Br J Radiol
On the Metabolism of Tumors in the Body
Whole-body PET: Physiologic and artifactual fluoro-deoxyglucose accumulations
J Nucl Med
Influence of the blood glucose concentration on FDG uptake in cancer—A PET study
J Nucl Med
A tabulated summary of the FDG PET literature
J Nucl Med
Leitlinie zur Tumordarstellung mit (F-18)-Fluordeoxyglukose (FDG)
Nuklearmedizin
FDG-PET for clinical useResults of the 3rd German Interdisciplinary Consensus Conference, “Onko-PET III”, 21 July and 19 September 2000
Eur J Nucl Med
Values and limitations of 18F-fluorodeoxyglucosepositronemission tomography with preoperative evaluation of patients with pancreatic masses
Pancreas
Relevance of positron emission tomography (PET) in oncology
Strahlenther Onkol
Prospective comparison of 18F-FDG PET with conventional imaging modalities (CT, MRI, US) in lymph node staging of head and neck cancer
Eur J Nucl Med
18FDGPET in 733 consecutive patients with or without side-by-side CT evaluation: Analysis of 921 lesions
Nuklearmedizin
Side-by-side reading of PET and CT scans in oncology: Which patients might profit from integrated PET/CT?
Eur J Nucl Med Mol Imaging
Respiration artifacts in whole-body (18)F-FDG PET/CT studies with combined PET/CT tomographs employing spiral CT technology with 1-16 detector rows
Eur J Nucl Med Mol Imaging
Dualmodality PET/CT tomography for clinical oncology
Q J Nucl Med
To enhance or not to enhance?18F-FDG and CT contrast agents in dual-modality 18F-FDG PET/CT
J Nucl Med
Focal tracer uptake: A potential artifact in contrast enhanced dual-modality PET/CT scans
J Nucl Med
Non–small-cell lung cancer: Dual-modality PET/CT in preoperative staging
Radiology
Acquisition protocol considerations for combined PET/CT imaging
J Nucl Med
PET/CT image coregistration in the thorax: Influence of respiration
Eur J Nucl Med Mol Imaging
PET/CT of the abdomen: Optimizing the patient breathing pattern
Eur Radiol
Dual-modality PET/CT imaging: The effect of respiratory motion on combined image quality in clinical oncology
Eur J Nucl Med Mol Imaging
PETCT: Accuracy of PET and CT spatial registration of lung lesions
Eur J Nucl Med Mol Imaging
Optimized intravenous contrast administration for diagnostic whole-body 18F-FDG PET/CT
J Nucl Med
The effect of different chemoembolization materials on CT-based attenuation correction in PET/CT
Rofo
Improvements in cancer staging with PET/CT: Literature-based evidence as of September 2006
J Nucl Med
Comparison between 18F-FDG PET, in-line PET/CT, and software fusion for restaging of recurrent colorectal cancer
J Nucl Med
The Will Rogers phenomenonStage migration and new diagnostic techniques as a source of misleading statistics for survival in cancer
N Engl J Med
FDG-PET/CT bei Bronchialkarzinomen
Der. Nuklearmediziner
Positron emission tomography and improved survival in patients with lung cancer: The Will Rogers phenomenon revisited
Arch Intern Med
Value of (124)I-PET/CT in staging of patients with differentiated thyroid cancer
Eur Radiol
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2021, International Journal of PharmaceuticsCitation Excerpt :These hybrid imaging techniques provide both the anatomical and spatial distribution of the probe in the tissue or organ of interest. Further, potentially harmful effects associated with radioactive probes used in PET/SPECT limit their unwarranted use (Bockisch et al., 2009; Histed et al., 2012; Könik et al., 2021; Nolte et al., 2020). Radiopharmaceuticals for therapy utilized radioisotopes that emit α-, β-particles, or Auger electrons.
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2021, BiomaterialsCitation Excerpt :It gains more accurate co-registration and provides important information about lesion benign and malignant tumor identification [11,12]. SPECT/CT has demonstrated excellent penetrating ability and is more practical for deep tissue imaging, especially for bone tissue [13–17]. In addition, as a necessary additional clinical diagnostic method to MRI, SPECT/CT is able to acquire the whole-body imaging for bone tumor detection with less examination time and less challenges for processing a multitude of images [15,18].