Detection of bone metastases in breast cancer by positron emission tomography

A novel immunocompetent model of metastatic prostate cancer-induced bone pain

BACKGROUND

Over 70% to 85% of men with advanced prostate cancer (PCa) develop bone metastases characterized by severe bone pain and increased likelihood of bone fracture. These clinical features result in decreased quality of life and act as a predictor of higher mortality. Mechanistically, the skeletal pathologies such as osteolytic lesions and abnormal osteoblastic activity drive these symptoms. The role of immune cells in bone cancer pain remains understudied, here we sought to recapitulate this symptomology in a murine model.

METHODS

The prostate cancer bone metastasis-induced pain model (CIBP) was established by transplanting a mouse prostate cancer cell line into the femur of immunocompetent mice. Pain development, gait dynamics, and the changes in emotional activities like depression and anxiety were evaluated. Animal tissues including femurs, dorsal root ganglion (DRG), and spinal cord were collected at killing and microcomputed tomography (μCT), histology/immunohistochemistry, and quantitative immunofluorescent analysis were performed.

RESULTS

Mice receiving prostate cancer cells showed a significantly lower threshold for paw withdrawal responses induced by mechanical stimulation compared with their control counterparts. Zero maze and DigiGait analyses indicated reduced and aberrant movement associated emotional activity compared with sham control at 8-weeks postinjection. The μCT analysis showed osteolytic and osteoblastic changes and a 50% reduction of the trabecular volumes within the prostate cancer group. Neurologically we demonstrated, increased calcitonin gene-related peptide (CGRP) and neuronal p75NTR immune-reactivities in both the projected terminals of the superficial dorsal horn and partial afferent neurons in DRG at L2 to L4 level in tumor-bearing mice. Furthermore, our data show elevated nerve growth factor (NGF) and TrkA immunoreactivities in the same segment of the superficial dorsal horn that were, however, not colocalized with CGRP and p75NTR .

CONCLUSIONS

This study describes a novel immunocompetent model of CIBP and demonstrates the contribution of NGF and p75NTR to chronic pain in bone metastasis.

Positron emission tomography (PET) radiotracers for prostate cancer imaging

Imaging plays an increasing role in prostate cancer diagnosis and staging. Accurate staging of prostate cancer is required for optimal treatment planning. In detecting extraprostatic cancer and sites of early recurrence, traditional imaging methods (computed tomography, magnetic resonance imaging, radionuclide bone scan) have suboptimal performance. This leaves a gap between known disease recurrence as indicated by rising prostate-specific antigen and the ability to localize the recurrence on imaging. Novel positron emission tomography (PET) agents including radiolabeled choline, fluciclovine (¹⁸F-FACBC), and agents targeting prostate-specific membrane antigen are being developed and tested to increase diagnostic performance of non-invasive prostate cancer localization. When combined with CT or MRI, these tracers offer a combination of functional information and anatomic localization that is superior to conventional imaging methods. These PET radiotracers have varying mechanisms and excretion patterns affecting their pharmacokinetics and diagnostic performance, which will be reviewed in this article.

A Comparison of Angiogenesis and Glycolytic Imaging in Patients With Clinical Suspected Locally Advanced Breast Cancer

F-FDG PET/CT imaging is an important diagnostic tool for accurate staging and assessment of response to neoadjuvant chemotherapy (NACT) in patients with locally advanced breast carcinoma (LABC). However, F-FDG being non-specific marker, it also accumulates in inflammatory conditions, leading to false positive results. Angiogenesis, an essential characteristic for tumor development, intrusion and metastasis can be imaged using Ga-labeled RGD tripeptide. We here depict a series of clinically staged LABC patients who underwent both Ga-DOTA-RGD2 and F-FDG PET/CT imaging for staging and illustrate the similarities and significant differences between the two tracers.

Species-dependent extracranial manifestations of a brain seeking breast cancer cell line

PURPOSE

Metastatic brain tumors pose a severe problem in the treatment of patients with breast carcinoma. Preclinical models have been shown to play an important role in unraveling the underlying mechanisms behind the metastatic process and evaluation of new therapeutic approaches. As the size of the rat brain allows improved in vivo imaging, we attempted to establish a rat model for breast cancer brain metastasis that allows follow-up by 7 tesla (7T) preclinical Magnetic Resonance Imaging (MRI).

PROCEDURES

Green fluorescent protein-transduced (eGFP) MDA-MB-231br breast cancer cells were labeled with micron-sized particles of iron oxide (MPIOs) and intracardially injected in the left ventricle of female nude rats and mice. 7T preclinical MRI was performed to show the initial distribution of MPIO-labeled cancer cells and to visualize metastasis in the brain. Occurrence of potential metastasis outside the brain was evaluated by 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET)/computed tomography (CT) and potential bone lesions were assessed using [18F]sodium fluoride ([18F]NaF) PET/CT.

RESULTS

The first signs of brain metastasis development were visible as hyperintensities on T2-weighted (T2w) MR images acquired 3 weeks after intracardiac injection in rats and mice. Early formation of unexpected bone metastasis in rats was clinically observed and assessed using PET/CT. Almost no bone metastasis development was observed in mice after PET/CT evaluation.

CONCLUSIONS

Our results suggest that the metastatic propensity of the MDA-MB-231br/eGFP cancer cell line outside the brain is species-dependent. Because of early and abundant formation of bone metastasis with the MDA-MB-231br/eGFP cancer cell line, this rat model is currently not suitable for investigating brain metastasis as a single disease model nor for evaluation of novel brain metastasis treatment strategies.

Management of Primary Osseous Spinal Tumors with PET

Knowledge of the PET imaging findings of osseous spinal neoplasms is essential, because they are common incidental findings on PET scans done for staging of unrelated primary malignancies. Additionally, PET can help differentiate lesions that are not clearly defined by anatomic modalities alone. PET can also be used for follow-up of aggressive tumors to assess response to treatment, often proving superior to CT or MR imaging alone for this purpose. This review discusses the role of PET/CT and PET/MR imaging in the diagnosis and management of primary benign and malignant osseous tumors of the spine.

Role of Fludeoxyglucose in Breast Cancer: Treatment Response

After an overview of the principles of fludeoxyglucose-PET/computed tomography (CT) in breast cancer, its advantages and limits to evaluate treatment response are discussed. The metabolic information is helpful for early assessment of the response to neoadjuvant chemotherapy and could be used to monitor treatment, especially in aggressive breast cancer subtypes. PET/CT is also a powerful method for early assessment of the treatment response in the metastatic setting. It allows evaluation of different sites of metastases in a single examination and detection of a heterogeneous response. However, to use PET/CT to assess responses, methodology for image acquisition and analysis needs standardization.

Acute Lumbar Back Pain

BACKGROUND

Back pain has many causes. In Germany, about 70% of adults have at least one episode of back pain per year.

METHODS

This review is based on a selective literature search and on the German National Disease Management Guideline for Low Back Pain.

RESULTS

The physician taking the history from a patient with back pain should ask about the nature, onset, course, localization, and radiation of the pain and its dependence on physical activity and/or emotional stress. In the differential diagnosis, neurologic deficits and any "red flags" suggesting dangerous conditions such as spinal fracture, bacterial infection, and tumors must be ruled out. If no specific cause of the pain can be identified, no imaging studies are indicated on initial presentation. The treatment of acute, nonspecific low back pain focuses on pain relief and functional improvement. Adequate patient education and counseling are essential. Exercise therapy is no more effective than the continuation of normal daily activities. Restriction of activity, including bed rest, is of no benefit and merely prolongs recovery and the resumption of normal activity. Further diagnostic testing is indicated if there is any suspicion of a fracture, infection, or tumor.

CONCLUSION

After dangerous conditions have been ruled out, low back pain can be pragmatically classified as either nonspecific or specific. More research is needed so that the diagnostic assessment and individualized treatment of acute lower back pain can be further refined.

Comparative diagnostic accuracy of 18F-FDG PET/CT for breast cancer recurrence

In the last decades, in addition to conventional imaging techniques and magnetic resonance imaging (MRI), ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) has been shown to be relevant in the detection and management of breast cancer recurrence in doubtful cases in selected groups of patients. While there are no conclusive data indicating that imaging tests, including FDG PET/CT, produce a survival benefit in asymptomatic patients, FDG PET/CT can be useful for identifying the site of relapse when traditional imaging methods are equivocal or conflicting and for identifying or confirming isolated loco-regional relapse or isolated metastatic lesions. The present narrative review deals with the potential role of FDG PET in these clinical settings by comparing its accuracy and impact with conventional imaging modalities such as CT, ultrasound, bone scan, ¹⁸F-sodium fluoride PET/CT (¹⁸F-NaF PET/CT) as well as MRI. Patient-focused perspectives in terms of patients' satisfaction and acceptability are also discussed.

Evaluation of Prostate Cancer Bone Metastases with 18F-NaF and 18F-Fluorocholine PET/CT

¹⁸F-fluorocholine is a specific promising agent for imaging tumor cell proliferation, particularly in prostate cancer, using PET/CT. It is a beneficial tool in the early detection of marrow-based metastases because it excludes distant metastases and evaluates the response to hormone therapy. In addition, ¹⁸F-fluorocholine has the potential to differentiate between degenerative and malignant osseous abnormalities because degenerative changes are not choline-avid; however, the agent may accumulate in recent traumatic bony lesions. On the other hand, ¹⁸F-NaF PET/CT can indicate increased bone turnover and is generally used in the assessment of primary and secondary osseous malignancies, the evaluation of response to treatment, and the clarification of abnormalities on other imaging modalities or clinical data. ¹⁸F-NaF PET/CT is a highly sensitive method in the evaluation of bone metastases from prostate cancer, but it has problematic specificity, mainly because of tracer accumulation in degenerative and inflammatory bone diseases. In summary, ¹⁸F-NaF PET/CT is a highly sensitive method, but ¹⁸F-fluorocholine PET/CT can detect early bone marrow metastases and provide greater specificity in the detection of bone metastases in patients with prostate cancer. However, the difference seems not to be significant.

Comparisons between glucose analogue 2-deoxy-2-(18F)fluoro-D-glucose and 18F-sodium fluoride positron emission tomography/computed tomography in breast cancer patients with bone lesions

AIM: To compare 2-deoxy-2-(¹⁸F)fluoro-D-glucose(¹⁸F-FDG) and ¹⁸F-sodium (¹⁸F-NaF) positron emission tomography/computed tomography (PET/CT) accuracy in breast cancer patients with clinically/radiologically suspected or known bone metastases.

METHODS: A total of 45 consecutive patients with breast cancer and the presence or clinical/biochemical or radiological suspicion of bone metastatic disease underwent ¹⁸F-FDG and ¹⁸F-fluoride PET/CT. Imaging results were compared with histopathology when available, or clinical and radiological follow-up of at least 1 year. For each technique we calculated: Sensitivity (Se), specificity (Sp), overall accuracy, positive and negative predictive values, error rate, and Youden’s index. McNemar’s χ² test was used to test the difference in sensitivity and specificity between the two diagnostic methods. All analyses were computed on a patient basis, and then on a lesion basis, with consideration ofthe density of independent lesions on the co-registered CT (sclerotic, lytic, mixed, no-lesions) and the divergent site of disease (skull, spine, ribs, extremities, pelvis). The impact of adding ¹⁸F-NaF PET/CT to the work-up of patients was also measured in terms of change in their management due to ¹⁸F-NaF PET/CT findings.

RESULTS: The two imaging methods of ¹⁸F-FDG and ¹⁸F-fluoride PET/CT were significantly different at the patient-based analysis: Accuracy was 86.7% and 84.4%, respectively (McNemar’s χ² = 6.23, df = 1, P = 0.01). Overall, 244 bone lesions were detected in our analysis. The overall accuracy of the two methods was significantly different at lesion-based analysis (McNemar’s χ² = 93.4, df = 1, P < 0.0001). In the lesion density-based and site-based analysis, ¹⁸F-FDG PET/CT provided more accurate results in the detection of CT-negative metastasis (P < 0.002) and vertebral localizations (P < 0.002); ¹⁸F-NaF PET/CT was more accurate in detecting sclerotic (P < 0.005) and rib lesions (P < 0.04). ¹⁸F-NaF PET/CT led to a change of management in 3 of the 45 patients (6.6%) by revealing findings that were not detected at ¹⁸F-FDG PET/CT.

CONCLUSION: ¹⁸F-FDG PET/CT is a reliable imaging tool in the detection of bone metastasis in most cases, with a diagnostic accuracy that is slightly, but significantly, superior to that of ¹⁸F-NaF PET/CT in the general population of breast cancer patients. However, the extremely high sensitivity of ¹⁸F-fluoride PET/CT can exploit its diagnostic potential in specific clinical settings (i.e., small CT-evident sclerotic lesions, high clinical suspicious of relapse, and negative ¹⁸F-FDG PET and conventional imaging).

Newer PET application with an old tracer: role of 18F-NaF skeletal PET/CT in oncologic practice

The skeleton is one of the most common sites for metastatic disease, particularly from breast and prostate cancer. Bone metastases are associated with considerable morbidity, and accurate imaging of the skeleton is important in determining the appropriate therapeutic plan. Sodium fluoride labeled with fluorine 18 (sodium fluoride F 18 [(18)F-NaF]) is a positron-emitting radiopharmaceutical first introduced several decades ago for skeletal imaging. (18)F-NaF was approved for clinical use as a positron emission tomographic (PET) agent by the U.S. Food and Drug Administration in 1972. The early use of this agent was limited, given the difficulties of imaging its high-energy photons on the available gamma cameras. For skeletal imaging, it was eventually replaced by technetium 99m ((99m)Tc)-labeled agents because of the technical limitations of (18)F-NaF. During the past several years, the widespread availability and implementation of hybrid PET and computed tomographic (CT) dual-modality systems (PET/CT) have encouraged a renewed interest in (18)F-NaF PET/CT for routine clinical use in bone imaging. Because current PET/CT systems offer high sensitivity and spatial resolution, the use of (18)F-NaF has been reevaluated for the detection of malignant and nonmalignant osseous disease. Growing evidence suggests that (18)F-NaF PET/CT provides increased sensitivity and specificity in the detection of bone metastases. Furthermore, the favorable pharmacokinetics of (18)F-NaF, combined with the superior imaging characteristics of PET/CT, supports the routine clinical use of (18)F-NaF PET/CT for oncologic imaging for skeletal metastases. In this article, a review of the indications, imaging appearances, and utility of (18)F-NaF PET/CT in the evaluation of skeletal disease is provided, with an emphasis on oncologic imaging.

Contemporary approaches for imaging skeletal metastasis

The skeleton is a common site of cancer metastasis. Notably high incidences of bone lesions are found for breast, prostate, and renal carcinoma. Malignant bone tumors result in significant patient morbidity. Identification of these lesions is a critical step to accurately stratify patients, guide treatment course, monitor disease progression, and evaluate response to therapy. Diagnosis of cancer in the skeleton typically relies on indirect bone-targeted radiotracer uptake at sites of active bone remodeling. In this manuscript, we discuss established and emerging tools and techniques for detection of bone lesions, quantification of skeletal tumor burden, and current clinical challenges.

Evaluation of radiographic and metabolic changes in bone metastases in response to systemic therapy with (18)FDG-PET/CT

BACKGROUND

The aim of the study was to retrospectively evaluate radiographic and metabolic changes in bone metastases in response to systemic therapy with (18)FDG-PET/CT and determine their roles on the evaluation of therapy response.

PATIENTS AND METHODS

We retrospectively evaluated radiographic and metabolic characteristics of bone metastases in 30 patients who were referred for the evaluation of response to systemic therapy with (18)FDG-PET/CT. All patients underwent integrated (18)FDG-PET/CT before and after treatment.

RESULTS

The baseline radiographic patterns of the target lesions in responders group were lytic, sclerotic, mixed and CT negative; after treatment the radiographic patterns of all target lesions changed to a sclerotic pattern and attenuation increased (p = 0.012) and metabolic activity decreased (p = 0.012). A correlation was found between decreasing metabolic activity and increasing attenuation of the target lesions (r = -0.55) (p = 0.026). However, in nonresponders group, the baseline radiologic patterns of the target lesions were lytic, blastic, mixed and CT negative; after treatment all lytic target lesions remained the same and one CT negative lesion turned to lytic pattern and the attenuation of the target lesions decreased (p ± 0.12) and metabolic activity increased (p = 0.012). A correlation was found between increasing metabolic activity and decreasing attenuation (r = -0.65) (p = 0.032). An exception of this rule was seen in baseline blastic metastases which progressed with increasing in size, metabolic activity and attenuation.

CONCLUSIONS

This study shows that the metabolic activity of lesions is a more reliable parameter than the radiographic patterns for the evaluation of therapy response.

Diagnosis and surgical management of breast cancer metastatic to the spine

Breast cancer is the most common malignancy and the second leading cause of death in Western women. Breast cancer most commonly metastasizes to the bone and has a particular affinity with the spine, accounting for 2/3 of osseous metastases discovered. With significant improvements in cancer therapies, the number of patients at risk for symptomatic spinal metastases is likely to increase. Patients may suffer from intractable pain and neurological dysfunction, negatively influencing their quality of life. Timely diagnosis of patients is crucial and has been aided by several breakthrough advances in imaging techniques which aid in detection, staging, and follow-up of bone metastases. Breast metastases are usually responsive to hormonal therapy and pharmacologic interventions, but skeletal metastases often require surgical intervention. The treatments are palliative but goals include the preserving or restoring neurologic function, ensuring spinal stability, and relieving pain. Advances in surgical techniques and instrumentation have allowed more effective decompression and stabilization of the spine, and with the support of recent evidence the trend has shifted towards using more advanced surgical options in appropriately selected patients. In this review, the clinical presentation, diagnosis, patient selection, and surgical management of breast cancer metastatic to the spine are discussed.

Performance of whole-body integrated 18F-FDG PET/MR in comparison to PET/CT for evaluation of malignant bone lesions

Because of its higher soft-tissue contrast, whole-body integrated PET/MR offers potential advantages over PET/CT for evaluation of bone lesions. However, unlike PET/CT, PET/MR ignores the contribution of cortical bone in the attenuation map. Thus, the aims of this study were to evaluate the diagnostic performance of whole-body integrated (18)F-FDG PET/MR specifically for bone lesions and to analyze differences in standardized uptake value (SUV) quantification between PET/MR and PET/CT.

METHODS

One hundred nineteen patients with (18)F-FDG-avid primary malignancies underwent a single-injection, dual-imaging protocol using (18)F-FDG on a PET/CT scanner and a subsequent PET/MR scan with a T1-weighted volumetric interpolated breath-hold examination (VIBE) Dixon sequence for attenuation correction and an unenhanced coronal T1-weighted turbo spin-echo (TSE) sequence for bone analysis. Three sets of images (CT with PET [from PET/CT; set A], T1-weighted VIBE Dixon with PET [set B], and T1-weighted TSE with PET [both from PET/MR; set C]) were analyzed. Two readers rated every lesion using a 4-point scale for lesion conspicuity on PET, a 4-point scale for anatomic allocation of PET-positive lesions, and a 5-point scale for the nature of every lesion based on its appearance on morphologic imaging and uptake on PET. For all lesions and for representative regions of normal bone, SUV analysis was performed for PET/MR and PET/CT.

RESULTS

In total, 98 bone lesions were identified in 33 of 119 patients, and 630 regions of normal bone were analyzed. Visual lesion conspicuity on PET was comparable for PET/CT (mean rating, 2.82 ± 0.45) and PET/MR (2.75 ± 0.51; P = 0.3095). Anatomic delineation and allocation of suggestive lesions was significantly superior with T1-weighted TSE MRI (mean rating, 2.84 ± 0.42) compared with CT (2.57 ± 0.54, P = 0.0001) or T1-weighted VIBE Dixon MRI (2.57 ± 0.54, P = 0.0002). No significant difference in correct classification of malignant bone lesions was found among sets A (85/90), B (84/90), and C (86/90). For bone lesions and regions of normal bone, a highly significant correlation existed between the mean SUVs for PET/MR and PET/CT (R = 0.950 and 0.917, respectively, each P < 0.001). However, substantially lower mean SUVs were found for PET/MR than for PET/CT both for bone lesions (12.4% ± 15.5%) and for regions of normal bone (30.1% ± 27.5%).

CONCLUSION

Compared with PET/CT, fully integrated whole-body (18)F-FDG PET/MR is technically and clinically robust for evaluation of bone lesions despite differences in attenuation correction. PET/MR, including diagnostic T1-weighted TSE sequences, was superior to PET/CT for anatomic delineation and allocation of bone lesions. This finding might be of clinical relevance in selected cases--for example, primary bone tumors, early bone marrow infiltration, and tumors with low uptake on PET. Thus, a diagnostic T1-weighted TSE sequence is recommended as a routine protocol for oncologic PET/MR.

Performance of FDG PET/CT in the clinical management of breast cancer

In this analysis, the role of metabolic imaging with fluorine 18 fluorodeoxyglucose (FDG) in breast cancer is reviewed. The analysis was limited to recent works by using state-of-the-art positron emission tomography (PET)/computed tomography (CT) technology. The strengths and limitations of FDG PET/CT are examined in various clinical settings, and the following questions are answered: Is FDG PET/CT useful to differentiate malignant from benign breast lesions? Can FDG PET/CT replace sentinel node biopsy for axillary staging? What is the role of FDG PET/CT in initial staging of inflammatory or locally advanced breast cancer? What is the role of FDG PET/CT in initial staging of clinical stage IIA and IIB and primary operable stage IIIA breast cancer? How does FDG PET/CT compare with conventional techniques in the restaging of cancer in patients who are suspected of having disease recurrence? What is the role of FDG PET/CT in the assessment of early response to neoadjuvant therapy and of response to therapy for metastatic disease? Some recommendations for clinical practice are given.

The bone scan

Bone imaging continues to be the second greatest-volume nuclear imaging procedure, offering the advantage of total body examination, low cost, and high sensitivity. Its power rests in the physiological uptake and pathophysiologic behavior of 99m technetium (99m-Tc) diphosphonates. The diagnostic utility, sensitivity, specificity, and predictive value of 99m-Tc bone imaging for benign conditions and tumors was established when only planar imaging was available. Currently, nearly all bone scans are performed as a planar study (whole-body, 3-phase, or regional), with the radiologist often adding single-photon emission computed tomography (SPECT) imaging. Here we review many current indications for planar bone imaging, highlighting indications in which the planar data are often diagnostically sufficient, although diagnosis may be enhanced by SPECT. (18)F sodium fluoride positron emission tomography (PET) is also re-emerging as a bone agent, and had been considered interchangeable with 99m-Tc diphosphonates in the past. In addition to SPECT, new imaging modalities, including (18)F fluorodeoxyglucose, PET/CT, CT, magnetic resonance, and SPECT/CT, have been developed and can aid in evaluating benign and malignant bone disease. Because (18)F fluorodeoxyglucose is taken up by tumor cells and Tc diphosphonates are taken up in osteoblastic activity or osteoblastic healing reaction, both modalities are complementary. CT and magnetic resonance may supplement, but do not replace, bone imaging, which often detects pathology before anatomic changes are appreciated. We also stress the importance of dose reduction by reducing the dose of 99m-Tc diphosphonates and avoiding unnecessary CT acquisitions. In addition, we describe an approach to image interpretation that emphasizes communication with referring colleagues and correlation with appropriate history to significantly improve our impact on patient care.

Melorheostosis associated with peripheral form spondyloarthropathy: new image with 18-fluoride positron emission tomoscintigraphy coupled to computed tomography

Melorheostosis is a rare benign bone pathology which can be responsible for incapacitating pain and bone deformations. Its imaging abnormalities are often typical. We describe here the case of a patient with melorheostosis involving the lower limbs, associated with a peripheral form of inflammatory spondyloarthropathy, who underwent ¹⁸FNa positron emission tomography coupled to a computed tomography scan. Our objective is to present this new image, to show the value of this new modality and emphasize its advantages compared to the ^99mTechnetium bone scan.

Comparison of 18F-FDG PET/CT with bone scintigraphy for detection of bone metastasis: a meta-analysis

BACKGROUND

The skeleton is one of the favorable sites for the metastasis of almost all human malignant neoplasms. An accurate diagnosis of bone metastasis is crucial for the patient's staging and management.

PURPOSE

To investigate and compare diagnostic performance of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) and bone scintigraphy (BS) for detection of bone metastasis in malignancies using meta-analysis.

MATERIAL AND METHODS

PubMed (Medline included) was searched for relevant articles. We assessed the methodological quality with Quality Assessment of Diagnosis Accuracy Studies (QUADAS) score tool, and used statistical software to obtain pooled estimates of sensitivity, specificity, diagnostic odds ratio (DOR), and summary receiver-operating characteristic (SROC) curve.

RESULTS

Six studies met inclusion criteria. For 18F-FDG PET/CT, the pooled sensitivity and specificity were 0.934 and 0.975, respectively. The pooled positive likelihood ratio (LR+), negative likelihood ratio (LR-) and diagnostic odds ratio (DOR) were 34.990, 0.068 and 559.02, respectively. The area under the SROC curve was 0.9854. For BS, the pooled sensitivity, specificity, LR + , LR- and DOR were 0.706 (0.642-0.764), 0.911 (0.896-0.926), 13.982 (2.419-80.817), 0.319 (0.143-0.712), and 60.420 (21.393-170.64), respectively. The area under the SROC curve was 0.9386.

CONCLUSION

The results indicate that 18F-FDG PET/CT do have both higher sensitivity and specificity than bone scintigraphy for detecting metastatic bone tumor. However, further research is needed to evaluate the diagnostic performance of 18F-FDG PET/CT and BS in each common malignancy.

The yield of 18F-FDG PET/CT in patients with clinical stage IIA, IIB, or IIIA breast cancer: a prospective study

The purpose of this study was to prospectively evaluate the role of (18)F-FDG PET/CT in patients with stage IIA, IIB, or IIIA breast cancer.

METHODS

During 56 mo, 131 consecutive patients with large (>2 cm) breast cancer and clinical stage IIA, IIB, or IIIA (based on clinical examination, mammography, breast MRI, and ultrasonography) underwent (18)F-FDG PET/CT. The nuclear physician was unaware of the results of any other procedure (bone scan, chest radiography, liver ultrasound, or thoracoabdominal CT scan).

RESULTS

Of the 131 examined patients, 36 had clinical stage IIA (34 T2N0 and 2 T1N1), 48 stage IIB (20 T3N0 and 28 T2N1), and 47 stage IIIA (29 T3N1, 9 T2N2, and 9 T3N2). (18)F-FDG PET/CT modified staging for 5.6% of stage IIA patients, for 14.6% of stage IIB patients, and for 27.6% of stage IIIA patients. However, within stage IIIA, the yield was specifically high among the 18 patients with N2 disease (56% stage modification). When considering stage IIB and primary operable IIIA (T3N1) together, the yield of (18)F-FDG PET/CT was 13% (10/77); extraaxillary regional lymph nodes were detected in 5 and distant metastases in 7 patients. In this series, (18)F-FDG PET/CT outperformed bone scanning, with only 1 misclassification versus 8 for bone scanning (P = 0.036).

CONCLUSION

(18)F-FDG PET/CT provided useful information in 13% of patients with clinical T3N0, T2N1, or T3N1 disease. The yield was more modest in patients with stage IIA. The high yield in the case of N2 disease demonstrates that stage IIIA comprises 2 quite distinct groups of patients.

Targeted nuclear imaging of breast cancer: status of radiotracer development and clinical applications

Breast cancer is the most common cancer in women worldwide. Molecular imaging plays an important role in breast cancer diagnosis, staging, and treatment response evaluation. Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are the main clinical molecular imaging modalities that are based on the detection of radiotracers. This article discusses the typical radiotracers used for breast cancer imaging by PET and SPECT. In addition, radiotracers that are currently applied for human breast cancer imaging or under clinical trials are also reviewed in compliance with the categories of tumor-specific targets to which they are aimed at.

Behavioral, medical imaging and histopathological features of a new rat model of bone cancer pain

Pre-clinical bone cancer pain models mimicking the human condition are required to respond to clinical realities. Breast or prostate cancer patients coping with bone metastases experience intractable pain, which affects their quality of life. Advanced monitoring is thus required to clarify bone cancer pain mechanisms and refine treatments. In our model of rat femoral mammary carcinoma MRMT-1 cell implantation, pain onset and tumor growth were monitored for 21 days. The surgical procedure performed without arthrotomy allowed recording of incidental pain in free-moving rats. Along with the gradual development of mechanical allodynia and hyperalgesia, behavioral signs of ambulatory pain were detected at day 14 by using a dynamic weight-bearing apparatus. Osteopenia was revealed from day 14 concomitantly with disorganization of the trabecular architecture (µCT). Bone metastases were visualized as early as day 8 by MRI (T₁-Gd-DTPA) before pain detection. PET (Na¹⁸F) co-registration revealed intra-osseous activity, as determined by anatomical superimposition over MRI in accordance with osteoclastic hyperactivity (TRAP staining). Pain and bone destruction were aggravated with time. Bone remodeling was accompanied by c-Fos (spinal) and ATF3 (DRG) neuronal activation, sustained by astrocyte (GFAP) and microglia (Iba1) reactivity in lumbar spinal cord. Our animal model demonstrates the importance of simultaneously recording pain and tumor progression and will allow us to better characterize therapeutic strategies in the future.

Assessment of Response to Therapy for Bone Metastases: Is it Still a Challenge in Oncology?

Bone is one of the most common sites of metastases from cancer. Most anticancer treatments are highly toxic but only a fraction of all patients respond to them. Guidelines are needed to evaluate the response in the routine practice of oncology as well as in clinical trials in which new treatment options are evaluated. All current imaging procedures have major limitations. This article reviews old and new criteria for response evaluation. The major problem of accurate response evaluation in bone disease is discussed in detail. Some examples from our daily practice illustrate the difficulties. The indications for bone biopsy are also reviewed.

Breast cancer: role of SPECT and PET in imaging bone metastases

Breast cancer is the most common cause of bone metastases in women. Imaging studies are useful to identify bone involvement and associated complications, for follow-up of disease spread and for the assessment of response to therapy. Bone scintigraphy with (99m)technetium-labeled diphosphonates is most widely used, due to its availability, high sensitivity, and low cost, despite the relatively low specificity. The addition of single-photon emission computed tomography and recently single-photon emission computed tomography/computed tomography improves the diagnostic accuracy of this modality. Serial follow-up scans can demonstrate disease progression, but this method is less accurate in determining response to treatment. Positron emission tomography (PET), a tomographic modality with improved resolution shows improved sensitivity and specificity. (18)F-fluorodeoxyglucose (FDG)-PET is the most common clinically used procedure. FDG is taken up by the tumor cells and has therefore the advantage of demonstrating the presence of disease in both bone and soft tissues. FDG-PET is highly sensitive mainly in diagnosis of early metastatic disease, which may still be confined to the bone marrow, as well as for the detection of lytic bone metastases and can be also reliably used to monitor response to therapy. For the detection of sclerotic lesions, however, imaging with a bone-seeking tracer such as (18)F-fluoride, may have a complementary role. As a nonspecific skeletal imaging tracer, (18)F-fluoride has great potential, being more sensitive than bone scintigraphy and when PET/computed tomography is performed it is highly accurate for detection of both lytic and sclerotic lesions and to distinguish benign from malignant skeletal findings.

Detection of hematogenous bone metastasis in cervical cancer: 18F-fluorodeoxyglucose-positron emission tomography versus computed tomography and magnetic resonance imaging

BACKGROUND

In this large-scale, retrospective study, the authors evaluated the diagnostic performances of computed tomography (CT), magnetic resonance (MR) imaging, and (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) in detecting hematogenous bone metastasis in patients with cervical cancer. The associated risk factors also were analyzed.

METHODS

Patients with invasive cervical cancer who had both (18)F-FDG-PET studies and CT or MR imaging studies were selected. Patients who had either International Federation of Gynecology and Obstetrics (FIGO) stage III/IV disease or positive lymph node metastasis at the time of primary staging and patients who had suspected recurrent disease were included in the analyses. The diagnostic performances of PET was compared with the performance of CT and MR imaging by using the area under the receiver-operating-characteristic curve (AUC). Both univariate and multivariate analyses were applied to assess the risk factors for hematogenous bone metastasis at primary staging.

RESULTS

PET was more sensitive than CT (P = .004) and was more specific than MR imaging (P = .04). The diagnostic performance of PET was significantly superior to the performance CT (AUC, 0.964 vs 0.662; P < .001) and MR (AUC, 0.966 vs 0.833; P = .033). Both FIGO stage and the extent of lymph node metastases were associated with hematogenous bone metastasis in univariate analysis. However, the extent of lymph node metastases was the only significant risk factor in multivariate analysis (P = .025).

CONCLUSIONS

The current study demonstrated the superiority of (18)F-FDG-PET over CT and MR imaging for detecting hematogenous bone metastasis in patients with advanced cervical cancer. Hematogenous bone metastasis in cervical cancer was associated with the extent of lymph node metastases rather than with FIGO stage.

Treatment Options for Breast Cancer and Bone Metastases

The most common destination for breast cancer metastases is bone. If bone metastases are detected, treatment algorithms should include the continuation of cytoreductive therapy with the addition of treatment to counter skeletal-related events, including bone pain. The range of current treatment options includes bisphosphonates, surgical intervention to improve structural integrity and palliative focal radiotherapy. This article focuses on the role of bisphosphonate therapy in metastatic breast cancer. Bisphosphonate therapy significantly reduces the impact of skeletal-related events, reduces bone pain and increases patient quality of life. Our current understanding is that bisphosphonates may also disrupt the metastatic process and reduce the development of bone lesions. Ultimately, this may lead to further expansion of bisphosphonate-based therapy in the future.

Orthopedic surgery implications of breast cancer

Breast cancer is the most common malignancy and the second leading cause of death in women. The metastatic involvement of bone denotes disease progression and decreased survival. Controversy exists regarding the exact pathophysiologic mechanism of metastasis and the different pathways that determine an osteoblastic versus osteoclastic bone compromise. Several breakthrough advances in imaging techniques aid in the detection, staging and follow-up of bone metastases. Although usually responsive to hormonal therapy and pharmacologic interventions, skeletal metastases often require some type of surgical intervention. Orthopedic surgeons should establish an active role in the multidisciplinary treatment of patients with breast cancer.