The role of computed tomography in the detection of bone metastases in breast cancer patients

Diagnostic Accuracy of PET with Different Radiotracers versus Bone Scintigraphy for Detecting Bone Metastases of Breast Cancer: A Systematic Review and a Meta-Analysis

Due to the importance of correct and timely diagnosis of bone metastases in advanced breast cancer (BrC), we performed a meta-analysis evaluating the diagnostic accuracy of [18F]FDG, or Na[18F]F PET, PET(/CT), and (/MRI) versus [99mTc]Tc-diphosphonates bone scintigraphy (BS). The PubMed, Embase, Scopus, and Scholar electronic databases were searched. The results of the selected studies were analyzed using pooled sensitivity and specificity, diagnostic odds ratio (DOR), positive-negative likelihood ratio (LR+-LR-), and summary receiver-operating characteristic (SROC) curves. Eleven studies including 753 BrC patients were included in the meta-analysis. The patient-based pooled values of sensitivity, specificity, and area under the SROC curve (AUC) for BS (with 95% confidence interval values) were 90% (86-93), 91% (87-94), and 0.93, respectively. These indices for [18F]FDG PET(/CT) were 92% (88-95), 99% (96-100), and 0.99, respectively, and for Na[18F]F PET(/CT) were 96% (90-99), 81% (72-88), and 0.99, respectively. BS has good diagnostic performance in detecting BrC bone metastases. However, due to the higher and balanced sensitivity and specificity of [18F]FDG PET(/CT) compared to BS and Na[18F]F PET(/CT), and its advantage in evaluating extra-skeletal lesions, [18F]FDG PET(/CT) should be the preferred multimodal imaging method for evaluating bone metastases of BrC, if available.

Prospective comparison of the diagnostic accuracy of 18F-FDG PET/MRI, MRI, CT, and bone scintigraphy for the detection of bone metastases in the initial staging of primary breast cancer patients

OBJECTIVES

To compare the diagnostic performance of [18F]FDG PET/MRI, MRI, CT, and bone scintigraphy for the detection of bone metastases in the initial staging of primary breast cancer patients.

MATERIAL AND METHODS

A cohort of 154 therapy-naive patients with newly diagnosed, histopathologically proven breast cancer was enrolled in this study prospectively. All patients underwent a whole-body [18F]FDG PET/MRI, computed tomography (CT) scan, and a bone scintigraphy prior to therapy. All datasets were evaluated regarding the presence of bone metastases. McNemar χ2 test was performed to compare sensitivity and specificity between the modalities.

RESULTS

Forty-one bone metastases were present in 7/154 patients (4.5%). Both [18F]FDG PET/MRI and MRI alone were able to detect all of the patients with histopathologically proven bone metastases (sensitivity 100%; specificity 100%) and did not miss any of the 41 malignant lesions (sensitivity 100%). CT detected 5/7 patients (sensitivity 71.4%; specificity 98.6%) and 23/41 lesions (sensitivity 56.1%). Bone scintigraphy detected only 2/7 patients (sensitivity 28.6%) and 15/41 lesions (sensitivity 36.6%). Furthermore, CT and scintigraphy led to false-positive findings of bone metastases in 2 patients and in 1 patient, respectively. The sensitivity of PET/MRI and MRI alone was significantly better compared with CT (p < 0.01, difference 43.9%) and bone scintigraphy (p < 0.01, difference 63.4%).

CONCLUSION

[18F]FDG PET/MRI and MRI are significantly better than CT or bone scintigraphy for the detection of bone metastases in patients with newly diagnosed breast cancer. Both CT and bone scintigraphy show a substantially limited sensitivity in detection of bone metastases.

KEY POINTS

• [18F]FDG PET/MRI and MRI alone are significantly superior to CT and bone scintigraphy for the detection of bone metastases in patients with newly diagnosed breast cancer. • Radiation-free whole-body MRI might serve as modality of choice in detection of bone metastases in breast cancer patients.

Temporal subtraction of low-dose and relatively thick-slice CT images with large deformation diffeomorphic metric mapping and adaptive voxel matching for detection of bone metastases: A STARD-compliant article

To evaluate the improvement of radiologist performance in detecting bone metastases at follow up low-dose computed tomography (CT) by using a temporal subtraction (TS) technique based on an advanced nonrigid image registration algorithm.Twelve patients with bone metastases (males, 5; females, 7; mean age, 64.8 ± 7.6 years; range 51-81 years) and 12 control patients without bone metastases (males, 5; females, 7; mean age, 64.8 ± 7.6 years; 51-81 years) were included, who underwent initial and follow-up CT examinations between December 2005 and July 2016. Initial CT images were registered to follow-up CT images by the algorithm, and TS images were created. Three radiologists independently assessed the bone metastases with and without the TS images. The reader averaged jackknife alternative free-response receiver operating characteristics figure of merit was used to compare the diagnostic accuracy.The reader-averaged values of the jackknife alternative free-response receiver operating characteristics figures of merit (θ) significantly improved from 0.687 for the readout without TS and 0.803 for the readout with TS (P value = .031. F statistic = 5.24). The changes in the absolute value of CT attenuations in true-positive lesions were significantly larger than those in false-negative lesions (P < .001). Using TS, segment-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the readout with TS were 66.7%, 98.9%, 94.4%, 90.9%, and 94.8%, respectively.The TS images can significantly improve the radiologist's performance in the detection of bone metastases on low-dose and relatively thick-slice CT.

The Established Nuclear Medicine Modalities for Imaging of Bone Metastases

Background:

The skeleton is one of the frequent site of metastases in advanced cancer. Prostate, breast and renal cancers mostly metastasize to bone.

Discussion:

Malignant tumors lead to significant morbidity and mortality. Identification of bone lesions is a crucial step in diagnosis of disease at early stage, monitoring of disease progression and evaluation of therapy. Diagnosis of cancer metastases is based on uptake of bone-targeted radioactive tracer at different bone remodeling sites.

Conclusion:

This manuscript summarizes already established and evolving nuclear medicine modalities (e.g. bone scan, SPECT, SPECT/CT, PET, PET/CT) for imaging of bone metastases.

Magnetic Resonance Imaging of Spinal Metastases

Sixty-six patients with spinal metastatic disease secondary to urological malignancy underwent magnetic resonance imaging. Twenty-eight patients had clinical evidence of spinal cord compression. MRI demonstrated metastatic cord compression in 16 cases, a benign cause in two cases, nerve root involvement in five cases. In seven patients MRI demonstrated spinal metastases which were not visible on plain radiographs and isotope bone scans. Nine patients had metastatic deposits involving the cauda equina and in a further 22 patients spinal metastases were an incidental finding during MRI for staging of the primary tumour. MRI is a sensitive method of imaging spinal metastases and provides a noninvasive means of assessing patients with spinal cord compression.

FDG avid breast cancer bone metastases silent on CT and scintigraphy: a case report with radiologic-pathologic correlation

Bone is the one of the most common distant metastatic sites in breast cancer. Routine initial breast cancer staging evaluation typically includes computed tomography (CT) and skeletal scintigraphy while 18F fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) is reserved for clinically high-risk cases. Since FDG PET-CT is not routinely performed during staging or surveillance evaluations, it is important for radiologists and clinicians to appreciate the limitations of bone metastasis detection on CT and scintigraphy. We present a case of bony metastases of invasive ductal carcinoma of the breast which were not detected on diagnostic CT or skeletal scintigraphy but were metabolically active on FDG PET-CT and evident on magnetic resonance. We provide a review of the literature and radiologic–pathologic correlation to explain the discordant imaging findings.

Detection of vertebral metastases: a meta-analysis comparing MRI, CT, PET, BS and BS with SPECT

OBJECTIVE

To perform a meta-analysis to compare the diagnostic value of magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), bone scintigraphy (BS) and BS with single-photon emission computed tomography (SPECT) in detecting vertebral metastases.

METHODS

Relevant original articles published from January 1995 to December 2015 were searched. Two reviewers independently extracted data. Software called "META-DiSc" was used to obtain pooled estimates of sensitivity, specificity, diagnostic odds ratio (DOR) and summary receiver operating characteristic (SROC) curves.

RESULTS

Twenty-three articles consisting of 33 studies fulfilled all inclusion criteria. On per-patient basis, for sensitivity, MRI = PET = SPECT > CT = BS ("=" indicated no significant difference, P > 0.05; ">" indicated significantly higher, P < 0.05). For specificity, MRI = CT = BS > SPECT > PET. For DOR, MRI > SPECT > BS > CT = PET. SROC curves for SPECT and MRI showed better diagnostic accuracy than others. On per-lesion basis, for sensitivity, PET = SPECT = MRI > BS > CT. For specificity, MRI = CT > PET = SPECT = BS. For DOR, MRI > SPECT > CT = PET > BS. SROC curves showed MRI had the best while CT had the lowest diagnostic accuracy.

CONCLUSION

For diagnosis of vertebral metastases, MRI was found to be the best modality and also better than other techniques on both per-patient and per-lesion basis.

Cervical Spine pain as a presenting complaint in metastatic pancreatic cancer: a case report

A 48 year-old female presented to her primary care physician with a two-month history of neck pain with negative cervical spine x-rays. During that office visit, the patient was noted to be tachycardic with EKG revealing ST depressions, which led to hospital admission. Acute coronary syndrome was ruled out, however, persistent neck pain warranted inpatient MRI of the cervical spine, which revealed a cervical spine lesion. Extensive investigation and biopsy ultimately confirmed stage IV pancreatic adenocarcinoma with metastases to the bone, liver, and likely lung. In the literature, the findings of a primary metastatic site being bone is rare with only a few case reports showing vertebral or sternal metastasis as the first clinical manifestation of pancreatic cancer. The uniqueness of this case lies in the only presenting complaint being cervical spine pain in the setting of extensive metastases to the liver, bone, and likely lung.

Rapid detection of bone metastasis at thoracoabdominal CT: accuracy and efficiency of a new visualization algorithm

PURPOSE

To retrospectively assess the use of a combination of cancellous bone reconstructions (CBR) and multiplanar reconstructions (MPRs) for the detection of bone metastases at thoracoabdominal computed tomography (CT) compared with the use of MPRs alone.

MATERIALS AND METHODS

The study was approved by the local institutional review board. Included were 156 consecutive patients with confirmed cancer who underwent a whole-body positron emission tomography (PET)/CT examination for clinical purposes (93 male and 63 female patients; mean age ± standard deviation, 59.8 years ± 14.9; range, 11-85 years). Only the CT images were processed with the CBR algorithm, which segments the bones and removes the cortical layer from the images. The PET images served as part of the reference standard. Images from 15 patients were used as a training set. Four radiologists independently evaluated images of half of the remaining 141 patients by using CBRs and MPRs together, and the other half by using MPRs only. Radiologists were blinded to patient names, and patient order was randomized. Results for detection rates and reporting time were recorded and compared with a standard of reference for each patient that was created by one senior radiologist and one nuclear medicine specialist by using all available CT and PET data, CBRs, and follow-up examinations. General estimation equations were used for statistical analysis.

RESULTS

There were 349 lesions found in 103 patients, with 203 classified as malignant. Each patient was assessed by two readers per method, leading to a total of 698 lesions. The detection rate for all bone lesions was 35% (247 of 698) for MPRs and 74% (520 of 698) when CBRs and MPRs were used together, which was significantly higher (P < .001). The average reading time decreased from 85 to 43 seconds (P < .001) when both reconstructions were used.

CONCLUSION

Advanced visualization of cancellous bone significantly increased the detection of bone metastases and reduced the time for interpretation.

Unilateral proptosis: an unusual presentation of prostatic carcinoma

A 68-year-old man presented acutely with periorbital pain and proptosis of the right eye, on a background of generalised pain and weight loss. Imaging showed bilateral signal abnormalities in the basal skull extending into the extraconal orbits with compression of the right optic nerve. His medical history revealed symptoms in keeping with benign prostatic hypertrophy. However, the prostate was irregular on rectal examination and prostate-specific antigen was markedly raised at 1880 ng/dl. A provisional diagnosis of metastatic prostatic carcinoma was made based on the clinical and radiological picture. This was later confirmed to be metastatic adenocarcinoma through means of tissue diagnosis.

The role of 18F-fluoride PET-CT in the detection of bone metastases in patients with breast, lung and prostate carcinoma: a comparison with FDG PET/CT and 99mTc-MDP bone scan

OBJECTIVES

We aimed to compare the role of (18)F-fluoride PET/CT, FDG PET/CT and (99m)Tc-MDP bone scans in the detection of bone metastases in patients with lung, breast and prostate carcinoma.

METHODS

This was a prospective study including patients for staging (S) and restaging (R). Seventy-two patients (23S, 49R) with infiltrating ductal breast carcinoma, 49 patients (25S, 24R) with prostate adenocarcinoma and 30 patients (17S, 13R) with non-small-cell lung carcinoma (NSCLC), without known bone metastases but with high risk/clinical suspicion for the same, underwent a (99m)Tc-MDP bone scan, FDG PET/CT and (18)F-fluoride PET/CT within 2 weeks. All scans were reviewed by two experienced nuclear medicine physicians, and the findings were correlated with MRI/thin-slice CT/skeletal survey. Histological verification was done wherever feasible.

RESULTS

Sensitivity and negative predictive value (NPV) of (18)F-fluoride PET/CT was 100 % in all three malignancies, while that of FDG PET/CT was 79 % and 73 % in NSCLC, 73 % and 80 % in breast cancer and 72 and 65 % in prostate cancer. Specificity and positive predictive value (PPV) of FDG PET/CT were 100 % in NSCLC and prostate and 97 % and 96 % in breast cancer. As compared to the (99m)Tc-MDP bone scan, all parameters were superior for (18)F-fluoride PET/CT in prostate and breast cancer, but sensitivity and NPV were equal in NSCLC. The MDP bone scan had superior sensitivity and NPV compared to FDG PET/CT but had low specificity and PPV.

CONCLUSION

To rule out bone metastases in cases where there is a high index of suspicion, (18)F-fluoride PET/CT is the most reliable investigation. (18)F-fluoride PET/CT has the potential to replace the (99m)Tc-MDP bone scan for the detection of bone metastases.

Reproducibility and clinical correlations of post-treatment changes on CT of prostate cancer bone metastases treated with chemotherapy

OBJECTIVES

The objective of this study was to determine whether, in patients with prostate cancer (PCa) bone metastases receiving chemotherapy, early post-treatment changes on CT are reproducible and associated with clinical outcomes.

METHODS

Blinded to outcomes, two radiologists with 1 year and 5 years of experience independently reviewed CTs obtained before and 3 months after chemotherapy initiation in 38 patients with bone metastases from castration-resistant PCa, recording the size, matrix and attenuation of ≤5 lesions; presence of new lesions, extraosseous components, periosteal reactions and cortical thickening; and overall CT assessment (improved, no change or worse). Kappa statistics were used to assess inter-reader agreement; the Kruskal-Wallis test and Cox regression model were used to evaluate associations.

RESULTS

Inter-reader agreement was low/fair for size change (concordance correlation coefficient=0.013), overall assessment and extraosseous involvement (κ=0.3), moderate for periosteal reaction and cortical thickening (κ=0.4-0.5), and substantial for CT attenuation (κ=0.7). Most metastases were blastic (Reader 1, 58%; Reader 2, 67%) or mixed lytic-blastic (Reader 1, 42%; Reader 2, 34%). No individual CT features correlated with survival. Readers 1 and 2 called the disease improved in 26% and 5% of patients, unchanged in 11% and 21%, and worse in 63% and 74%, respectively, with 64% interreader agreement. Overall CT assessment did not correlate with percentage change in prostate-specific antigen level. For the more experienced reader (Reader 2), patients with improved or unchanged disease had significantly longer median survival (p=0.036).

CONCLUSIONS

In PCa bone metastases, interreader agreement is low in overall CT post-treatment assessment and varies widely for individual CT features. Improved or stable disease identified by an experienced reader is statistically associated with longer survival.

Diagnosis of bone metastases: a meta-analysis comparing ¹⁸FDG PET, CT, MRI and bone scintigraphy

OBJECTIVE

To perform a meta-analysis to compare (18)FDG PET, CT, MRI and bone scintigraphy (BS) for the diagnosis of bone metastases.

METHODS

Databases including MEDLINE and EMBASE were searched for relevant original articles published from January 1995 to January 2010. Software was used to obtain pooled estimates of sensitivity, specificity and summary receiver operating characteristic curves (SROC).

RESULTS

67 articles consisting of 145 studies fulfilled all inclusion criteria. On per-patient basis, the pooled sensitivity estimates for PET, CT, MRI and BS were 89.7%, 72.9%, 90.6% and 86.0% respectively. PET=MRI>BS>CT. ("="indicated no significant difference, P > 0.05; ">" indicated significantly higher, P < 0.05). The pooled specificity estimates for PET, CT, MRI and BS were 96.8%, 94.8%, 95.4% and 81.4% respectively. PET = CT = MRI>BS. On per-lesion basis, the pooled sensitivity estimates for PET, CT, MRI and BS were 86.9%, 77.1%, 90.4% and 75.1% respectively. PET = MRI>BS>CT. The pooled specificity estimates for PET, CT, MRI and BS were 97.0%, 83.2%, 96.0% and 93.6% respectively. PET>MRI>BS>CT.

CONCLUSION

PET and MRI were found to be comparable and both significantly more accurate than CT and BS for the diagnosis of bone metastases.

A meta-analysis of 18FDG-PET, MRI and bone scintigraphy for diagnosis of bone metastases in patients with breast cancer

OBJECTIVE

To perform a meta-analysis comparing the diagnostic value of (18)FDG-PET, MRI, and bone scintigraphy (BS) in detecting bone metastases in patients with breast cancer.

MATERIALS AND METHODS

MEDLINE, EMBASE, Scopus, ScienceDirect, SpringerLink, Web of Knowledge, EBSCO, and the Cochrane Database of Systematic Review databases were searched for relevant original articles published from January 1995 to January 2010. Inclusion criteria was as follows: (18)FDG-PET, MRI or (99m)Tc-MDP BS was performed to detect bone metastases (the number of published CT studies was inadequate for meta-analysis and therefore could not be included in this study); sufficient data were presented to construct a 2 × 2 contingency table; histopathological analysis and/or close clinical and imaging follow-up for at least 6 months were used as the reference standard. Two reviewers independently assessed potentially eligible studies and extracted relevant data. A software program called "META-DiSc" was used to obtain the pooled estimates for sensitivity, specificity, diagnostic odds ratio (DOR), summary receiver operating characteristic (SROC) curves, and the *Q index for each modality.

RESULTS

Thirteen articles consisting of 23 studies fulfilled all inclusion criteria. On a per-patient basis, the pooled sensitivity estimates for MRI (97.1%) were significantly higher than those for PET (83.3%) and BS (87.0%; P <0.05). There was no significant difference between PET and BS (P <0.05). The pooled specificity estimates for PET (94.5%) and MRI (97.0%) were both significantly higher than those for BS (88.1%; P <0.05). There was no significant difference between PET and MRI (P >0.05). The pooled DOR estimates for MRI (298.5) were significantly higher than those for PET (82.1%) and BS (49.3%; P <0.05). There was no significant difference between PET and BS (P >0.05). The SROC curve for MRI showed better diagnostic accuracy than those for PET and BS. The SROC curve for PET was better than that for BS. The*Q index for MRI (0.935), PET (0.922), and BS (0.872) showed no significant difference (P ≥0.05). On a per-lesion basis, the pooled sensitivity estimates for BS (87.8%) were significantly higher than those for PET (52.7%; P <0.05). The pooled specificity estimates for PET (99.6%) were significantly higher than those for BS (96.1%; P <0.05).The pooled DOR estimates for PET (283.3) were significantly higher than those for BS (66.8%; P <0.05). The SROC curve for PET showed better diagnostic accuracy than that for BS. The*Q index for PET (0.941) was significantly higher than that for BS (0.893; P <0.05).

CONCLUSION

Magnetic resonance imaging was found to be better than (18)FDG-PET and BS for diagnosis of bone metastases in patients with breast cancer on a per-patient basis. On a per-lesion basis, (18)FDG-PET had lower sensitivity, higher specificity, a higher DOR, and a higher *Q index than BS.

PET/CT characteristics of isolated bone metastases in hepatocellular carcinoma

PURPOSE

To compare the prognostic implications and positron emission tomography (PET)/computed tomography (CT) characteristics of isolated bone metastasis secondary to hepatocellular carcinoma (HCC) with those of HCC metastases to bone and other sites.

MATERIALS AND METHODS

This study was approved by the institutional ethics committee, and informed consent was obtained from all patients. Extrahepatic metastases were diagnosed in 257 patients with HCC by using dual-tracer (carbon 11 [(11)C] acetate and fluorine 18 fluorodeoxyglucose [FDG]) PET/CT. Metastatic bone lesions were identified with visual inspection and semiquantitative assessment and confirmed with histopathologic examination and/or supported by findings at other radiologic examinations or serial PET/CT.

RESULTS

The frequency of bone metastasis from HCC was 19% (49 of 257 patients; eight patients had histopathologic proof and 41 had imaging proof). Metastasis isolated to bone (group 1, 30 of 257 patients [12%]) was more common than metastasis to bone and other sites (group 2, 19 of 257 patients [7%]). At lesion-based analysis of group 1 (71 index lesions; mean lesion size ± standard deviation, 3.25 cm ± 1.88), (11)C acetate PET was more sensitive than FDG PET (93% [66 of 71 lesions] vs 62% [44 of 71 lesions], respectively; P < .05). The combined sensitivity was 97% (69 of 71 lesions) with dual-tracer PET and 72% (51 of 71 lesions) with CT. At patient-based analysis, (11)C acetate PET had an incremental value of 23% (seven of 30 patients) over FDG PET. At lesion-based analysis of group 2, FDG PET was more sensitive than (11)C acetate PET (87% [33 of 38 lesions] vs 50% [19 of 38 lesions], respectively; P < .05). Tracer avidities of metastatic bone lesions were closely correlated with that of their corresponding primary HCC tumors. The median survival time was longer in group 1 than in group 2 (18 months vs 11 months, respectively; P < .05).

CONCLUSION

Isolated bone metastasis from HCC may not be as uncommon as previously believed. The detection of these metastases can be significantly enhanced with (11)C acetate PET compared with FDG PET alone. Identification of this group of patients also seems to have prognostic importance.

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.

NCCN Task Force Report: Bone Health in Cancer Care

Bone health and maintenance of bone integrity are important components of comprehensive cancer care in both early and late stages of disease. Risk factors for osteoporosis are increased in patients with cancer, including women with chemotherapy-induced ovarian failure, those treated with aromatase inhibitors for breast cancer, men receiving androgen-deprivation therapy for prostate cancer, and patients undergoing glucocorticoid therapy. The skeleton is a common site of metastatic cancer recurrence, and skeletal-related events are the cause of significant morbidity. The National Comprehensive Cancer Network (NCCN) convened a multidisciplinary task force on Bone Health in Cancer Care to discuss the progress made in identifying effective screening and therapeutic options for management of treatment-related bone loss; understanding the factors that result in bone metastases; managing skeletal metastases; and evolving strategies to reduce bone recurrences. This report summarizes presentations made at the meeting.

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.

Quantitative characterization of metastatic disease in the spine. Part II. Histogram-based analyses

Radiological imaging is essential to the appropriate management of patients with bone metastasis; however, there have been no widely accepted guidelines as to the optimal method for quantifying the potential impact of skeletal lesions or to evaluate response to treatment. The current inability to rapidly quantify the response of bone metastases excludes patients with cancer and bone disease from participating in clinical trials of many new treatments as these studies frequently require patients with so-called measurable disease. Computed tomography (CT) can provide excellent skeletal detail with a sensitivity for the diagnosis of bone metastases. The purpose of this study was to establish an objective method to quantitatively characterize disease in the bony spine using CT-based segmentations. It was hypothesized that histogram analysis of CT vertebral density distributions would enable standardized segmentation of tumor tissue and consequently allow quantification of disease in the metastatic spine. Thirty two healthy vertebral CT scans were first studied to establish a baseline characterization. The histograms of the trabecular centrums were found to be Gaussian distributions (average root-mean-square difference=30 voxel counts), as expected for a uniform material. Intrapatient vertebral level similarity was also observed as the means were not significantly different (p > 0.8). Thus, a patient-specific healthy vertebral body histogram is able to characterize healthy trabecular bone throughout that individual's thoracolumbar spine. Eleven metastatically involved vertebrae were analyzed to determine the characteristics of the lytic and blastic bone voxels relative to the healthy bone. Lytic and blastic tumors were segmented as connected areas with voxel intensities between specified thresholds. The tested thresholds were mu-1.0 sigma, mu - 1.5 sigma, and mu - 2.0 sigma, for lytic and mu + 2.0 sigma, mu+3.0 siema, and mu + 3.5 sigma for blastic tissue where mu and sigma were taken from the Gaussian characterization of a healthy level within the same patient. The ideal lytic and blastic segmentation thresholds were determined to be mu-sigma and mu + 2 sigma, respectively. Using the optimized thresholds to segment tumor tissue, a quantitative characterization of disease is possible to calculate tumor volumes, disease severity, and temporal progression or treatment effect. Our proposed histogram-based method for characterizing spinal metastases shows great potential in extending the quantitative capacity of CT-based radiographic evaluations.

Lytic Metastases in Thoracolumbar Spine: Computer-aided Detection at CT—Preliminary Study

PURPOSE

To evaluate the sensitivity of a computer-aided detection (CAD) system for detection of lytic thoracolumbar spinal lesions at body CT, with results of manual lesion segmentation as the reference standard.

MATERIALS AND METHODS

The study was HIPAA compliant and institutional review board approved; the institutional review board waived the need for informed consent. The CAD system segments the spine on CT images and searches for detections that match size, shape, location, and attenuation criteria. To reduce false-positive findings, 16 features for each detection were computed and fed to a classifier trained with manually segmented lesions. The data set consisted of CT studies of 50 patients (30 men, 20 women; range, 18-82 years; mean, 54.8 years) with 28 lesions. Studies were assigned to either a training (29 studies) or testing (21 studies) set. Sensitivities and false-positive rates (FPRs) for training and testing sets were calculated for these lesions, which were probable lytic metastases with areas 0.8 cm(2) or greater.

RESULTS

Training set sensitivity was 0.83 (10 of 12; 95% confidence interval: 0.51, 0.97), with an FPR of 7.4 per patient. Test set sensitivity was 0.94 (15 of 16; 95% confidence interval: 0.68, 1.00), with an FPR of 4.5 per patient. There was no significant difference between the CAD sensitivities of the training and test sets (P = .56). Of three false-negative findings, two were due to incomplete segmentation of the vertebral pedicle, and the third was rejected by the classifier. False-positive detections were most often attributable to veins that connect the basivertebral vein with the anterior venous plexus (106 [34%] of 310) and to low-attenuating disks (83 [27%] of 310).

CONCLUSION

This CAD system successfully identified probable lytic metastases in the thoracolumbar spine and generalized well to an independent testing set.

Bone imaging in metastatic breast cancer

Bone is the most common site to which breast cancer metastasizes. Imaging-by skeletal scintigraphy, plain radiography, computed tomography, or magnetic resonance imaging-is an essential part, and positron emission tomography or single-photon emission computed tomography have a potential of evaluating bone metastases, but no consensus exists as to the best modality for diagnosing the lesion and for assessing its response to treatment. Imaging bone metastases is problematic because the lesions can be osteolytic, osteoblastic, or mixed, and imaging modalities are based on either direct anatomic visualization of the bone or tumor or indirect measurements of bone or tumor metabolism. Although bone metastases can be treated, their response to treatment is considered "unmeasurable" according to existing response criteria. Therefore, the process by which oncologists and radiologists diagnose and monitor the response of bone metastases needs revision, and the current inability to assess the response of bone metastases excludes patients with breast cancer and bone disease from participating in clinical trials of new treatments for breast cancer. In this review of the MEDLINE literature, we discuss the pros and cons of each modality for diagnosing bone metastases and for assessing their response to treatment and we present a practical approach for diagnosis and assessment of bone metastasis.

Monitoring therapeutic response in skeletal metastases using dual-energy x-ray absorptiometry: a prospective feasibility study in breast cancer patients

Response to systemic therapy in breast cancer patients with lytic skeletal metastases manifests as a shift from increased bone resorption to new bone formation. We hypothesized that dual-energy x-ray absorptiometry (DXA) could be used to prospectively quantitate changes in bone mineral density (BMD) in metastatic skeletal lesions in breast cancer patients receiving systemic therapy. Nine metastatic breast cancer patients with one or more assessable lytic skeletal metastases receiving systemic therapy were prospectively evaluated with DXA, skeletal radiographs, computed tomography (CT), and radionuclide bone scans at baseline (t = 0 months, 2 months, and 6 months). The median (range) percentage change in BMD in skeletal lesions among patients responding to systemic therapy was 10.7% (0.1-21.85), 5.0% (-1.3-23.8), and 16.7% (-2.0-50.8) at 0-2, 2-6, and 0-6 months, respectively. Changes in BMD between 0-2, and 0-6 months were significant (Wilcoxin signed rank test; p = 0.013 and p = 0.017, respectively). The percentage change in BMD skeletal lesions between 0-2 and 2-6 months correlated with the changes imaged on skeletal x-rays (Spearman rank order correlation coefficient [Rs] = 0.511, p = 0.011) and CTs (Rs = 0.416, p = 0.046) but less so with bone scans (Rs = 0.293, p = 0.189). It is technically feasible to use DXA to prospectively monitor changes in lytic skeletal metastases in breast cancer patients receiving systemic therapy. The BMD of skeletal metastases increases in patients responding to treatment and was significantly correlated with the changes imaged on skeletal x-rays and CTs. Additional studies of DXA to evaluate response in skeletal metastasis are warranted.

Radiological detection of bone and bone marrow metastases

Bone scintigraphy is the primary method for the diagnosis of skeletal metastases. This investigation is sensitive, but the interpretation must be performed in the knowledge that it is also nonspecific. Despite this, a correct diagnosis can usually be achieved. The first-hand supplementary investigation, after a doubtful scintigraphic finding, is radiography. In most cases this is sufficient for a diagnosis. When a scintigraphic abnormality cannot be adequately explained, usually because of a negative radiographic examination, a more sensitive modality must be used. Computerized tomography offers increased sensitivity and specificity, and is primarily used for this purpose. In this way contrast resolution is increased and problems caused by obscuring tissue and complicated anatomy are reduced. Since bone metastases migrate via the active bone marrow an alternative supplementary investigation is bone marrow scintigraphy. Its usefulness is restricted by disturbing activity, from the liver and the spleen, which obscures a significant part of the active marrow, and by the fact that a lesion must be of a certain size to become apparent. Magnetic resonance imaging yields excellent images of the extension of a tumor in soft tissue. Owing to high costs and restricted availability it is still mainly used for preoperative location of metastases.

Isolated calcaneal metastasis in a patient with endometrial adenocarcinoma

A 55-year-old woman with a history of Stage IA endometrial adenocarcinoma, previously treated with surgery and intracavitary radiation therapy, had an isolated calcaneal metastasis. Normal radiographs led to a delay in the diagnosis of her relapse. An ankle computed tomographic scan finally identified a mass, and the surgical biopsy specimen confirmed the diagnosis. This is the first reported case of an isolated calcaneal metastasis in endometrial adenocarcinoma to the authors' knowledge.

Magnetic resonance imaging in the detection of skeletal metastases in patients with breast cancer

Eighty-four patients with breast cancer at high risk of bone metastases were investigated with magnetic resonance imaging (MRI) of the thoracolumbar spine. Of 58 patients with normal limited skeletal surveys (LSS) and bone scans (BS), 4 (7%) had MR images compatible with malignant infiltration. Fourteen patients had abnormal bone scans with normal or non-diagnostic plain films; 7 of these patients (50%) had MR images compatible with malignant infiltration. Twelve patients had single or multiple wedge collapses of uncertain aetiology on plain film; MR demonstrated metastatic disease as the cause of wedge collapse in 7 (58%). MRI may define a group of patients with extra-osseous relapse who have occult metastatic disease. Although the detection rate in patients with primary breast cancer is low (4/45), MRI is of value in determining the cause of wedge collapse in postmenopausal women with breast cancer and may elucidate the cause of an abnormal bone scan with normal or non-diagnostic plain films.

Imaging techniques in breast cancer

In the diagnosis of clinically inapparent breast cancer, mammography remains the most effective imaging modality, which is due in large part to its ability to detect microcalcifications. Of the ancillary modalities, sonography is the most useful because it readily differentiates cysts from other breast lesions. Internal mammary and axillary node imaging have been tried with varying levels of success, but false-positive and false-negative rates remain high with available techniques. Pulmonary metastases are best evaluated by chest X-ray with specificity increased by other imaging techniques. Liver and bone metastases may be screened for with isotope scans with computerized tomography, sonography, and magnetic resonance imaging, increasing the specificity of abnormal scans. CT and MRI are the most effective tools for evaluating CNS disease.

The value of pre-scheduled bone scintigraphies in breast cancer

During the first 10 years of Danish Breast Cancer Cooperative Group (DBCG), the subcommittee on bone scintigraphy has focused on the value of bone scintigraphy at the time of operation in all patients and then yearly in those considered to be primarily operable (stage I and II). Out of 1175 patients examined at time of operation, bone metastases could be verified by x-ray or histology in only 16, of whom the majority had bone pain and/or spread to other organs. Similarly, around 2.5% per year for the first 3 postoperative years and about 1% per year during the next 4 postoperative years had bone metastases verified by x-ray or histology within 12 months after the latest scheduled bone scintigraphy. It is concluded that bone scintigraphy is of no value in primarily operable patients with breast cancer, and that the examination should be reserved for patients with symptoms and/or signs of bone metastases and for patients with relapse.

The role of computed tomography in evaluation of skeletal metastases

Computed tomography was performed in 100 patients for additional evaluation of suspected skeletal metastases following radionuclide bone scanning in 86 patients and conventional radiography in all. A retrospective review of these cases revealed that the majority (78%) involved the spine and pelvis. Computed tomography contributed to the diagnosis of a malignancy by revealing a definite destructive lesion of bone in 27 patients who had an abnormal radionuclide bone scan, a normal or inconclusive radiograph, or both. It excluded a malignant lesion in 19 patients. In 38 patients, computed tomography provided additional information that contributed to such aspects of patient care as obtaining tissue diagnosis, determining the extent of lesions, and evaluating the response to treatment. False diagnoses were made in two patients. Detection by computed tomography of a skeletal lesion and histologic documentation, frequently by computed tomography-guided percutaneous needle aspiration biopsy, greatly curtailed an otherwise extensive search for the primary site. Furthermore, this information altered the treatment plan by obviating the need for radical resection or biopsy of the primary tumor and by directing the choice of an appropriate chemotherapeutic regimen.

Comparison of computed tomography and conventional radiology in the assessment of treatment response of lytic bony metastases in patients with carcinoma of the breast

Full skeletal survey, localised radiographs and computed tomography (CT) examinations were compared with clinical assessment in the evaluation of treatment response of bony metastases in 20 patients with carcinoma of the breast. Conventional radiology, skeletal survey and localised views compared poorly with clinical assessment agreeing in only 35% and 50% respectively. CT concurred with the clinical assessment in 65% of patients, particularly with respect to healing (86%). CT predicted the effect of treatment in six additional patients and this was confirmed on follow-up assessment. It is suggested that the use of skeletal surveys in monitoring treatment response is limited and that for critical evaluation of treatment CT should be the method of choice.

Computed tomography analysis of bone tumors: patterns of cortical destruction and soft tissue extension

Computed tomography was used to identify three different ways in which primary bone tumors may transgress a bony cortex. Analysis of the pattern of cortical transgression was used in conjunction with the presence or absence of matrix mineralization to classify correctly the lesion into one of four different diagnostic categories in 84% of 72 cases. These data demonstrate that certain types of behavior characterize the lesions under discussion and that this information may be helpful in diagnosis.

Osteolytic bone metastases in breast carcinoma pathogenesis, morbidity and bisphosphonate treatment

In this review different aspects of osteolytic bone metastasis of breast carcinoma including morbidity, pathogenesis, accompanying hypercalcaemia and treatment, are discussed. Bone metastases occur in many patients with breast cancer (percentages of up to 85% have been reported); although patients seldom die of bone metastases morbidity is pronounced. Literature data point out that humoral factors, such as prostaglandins and the recently described growth factors are of importance beside cell interactions between monocytes, lymphocytes, osteoclasts and tumour cells. Nowadays, no significance is attributed to parathyroid hormone (PTH) overproduction in this respect. The differential diagnosis between primary hyperparathyroidism and tumour-induced hypercalcaemia is not always easy biochemically; combinations of both do occur less frequently than has been assumed in the past. A new and promising line of investigations involves the growth factors, which can increase osteolytic bone resorption and may bind to epidermal growth factor (EGF) or PTH receptors, thus inducing some of the biological effects of PTH (including hypercalcaemia). Until recently it was exceedingly difficult to treat tumour-induced hypercalcaemia (TIH) (the acute condition). Since the availability of the bisphosphonates dichloromethylidene bisphosphonate (Cl2MDP) and 3-amino-1-hydroxypropylidene-1, l-bisphosphonate (APD) this treatment has become very simple. Preliminary results, derived from the literature, point out that bisphosphonate treatment might also be effective in providing long-term control.

Percutaneous vertebral biopsy: a review of 135 cases

The technique and advantages of undertaking percutaneous biopsy of vertebral lesions as a radiological procedure are described and illustrated with a series of 135 biopsies. An overall accuracy of 88.9% was achieved. The technique has a low morbidity and offers considerable advantages to the patient compared with open surgical biopsy.

Bone metastases in primary operable breast cancer. The role of serial scintigraphy

In 1978 and 1979, 1060 Danish patients with primary operable breast cancer were bone-scanned for osseous metastases before entering a nationwide therapeutical trial. A re-reading group interpreted the scans produced in 12 participating hospitals. As a consequence standardized guide-lines for interpretation were agreed upon from 1979. The frequency of positive bone scans suggesting bone metastases fell abruptly from 1978 to 1979, as read both locally and by the re-reading group. As measured statistically the difference between the interpretation of the local and the re-reading groups remained unchanged. Of the 1060 patients 760 were followed by repeated pre-scheduled scans 6 and 12 months after surgery until any kind of recurrence was diagnosed. Only 37 of the 760 patients (4.9%) developed bone metastases verified by radiology or autopsy during the first 2 yr after surgery. A single positive scan, especially performed 6 or 12 months after surgery, as well as two or three scans repeatedly staying or becoming positive increase significantly the risk of developing bone metastases within 12 months after the latest scan. In 13 of the 37 patients with otherwise subsequently proven bone metastases the latest scan(s) were negative. It is concluded that a fixed schedule of repeated bone scans in patients with breast cancer is not warranted.

Detection of breast carcinoma metastases in bone: relative merits of X-rays and skeletal scintigraphy

Of 1116 patients receiving primary treatment for breast carcinoma at the Royal Marsden Hospital since 1976, 651 had an abnormal bone scintigram either at primary diagnosis (378) or on subsequent follow-up (273) and 167 developed radiographically detectable bone metastases (21 at the time of primary diagnosis). Comparison of bone scintigrams and X-rays showed that scintigraphy was an inaccurate localiser of existing radiographic detectable metastases. If X-rays alone are used to detect bone metastases a limited examination with five plates will detect metastases with 92% accuracy. After primary surgery, routine X-ray screening for bone metastases is not necessary since it is possible to identify patients at risk on the basis of clinical examination, chest X-ray, and serum alkaline phosphatase and gamma-glutamyl transpeptidase levels.