Reliability of X-rays and bone scans for the assessment of changes in skeletal metastases from breast cancer

Potential biomarkers for the early detection of bone metastases

The clinical manifestations of bone metastases are diversified while many sites remain asymptomatic at early stage. As the early diagnosis method is not perfect and the early symptoms of tumor bone metastasis are not typical, bone metastasis is not easy to be detected. Therefore, the search for bone metastasis-related markers is effective for timely detection of tumor bone metastases and the development of drugs to inhibit bone metastases. As a result, bone metastases can only be diagnosed when symptoms are found, increasing the risk of developing skeletal-related event (SREs), which significantly impairs the patient's quality of life. Therefore, the early diagnosis of bone metastases is of great importance for the treatment and prognosis of cancer patients. Changes of bone metabolism indexes appear earlier in bone metastases, but the traditional biochemical indexes of bone metabolism lack of specificity and could be interfered by many factors, which limits their application in the study of bone metastases. Some new biomarkers of bone metastases have good diagnostic value, such as proteins, ncRNAs, circulating tumor cells (CTCs). Therefore, this study mainly reviewed the initial diagnostic biomarkers of bone metastases which were expected to provide references for the early detection of bone metastases.

Visual and quantitative evaluation of [18F]FES and [18F]FDHT PET in patients with metastatic breast cancer: an interobserver variability study

Purpose

Correct identification of tumour receptor status is important for treatment decisions in breast cancer. [¹⁸F]FES PET and [¹⁸F]FDHT PET allow non-invasive assessment of the oestrogen (ER) and androgen receptor (AR) status of individual lesions within a patient. Despite standardised analysis techniques, interobserver variability can significantly affect the interpretation of PET results and thus clinical applicability. The purpose of this study was to determine visual and quantitative interobserver variability of [¹⁸F]FES PET and [¹⁸F]FDHT PET interpretation in patients with metastatic breast cancer.

Methods

In this prospective, two-centre study, patients with ER-positive metastatic breast cancer underwent both [¹⁸F]FES and [¹⁸F]FDHT PET/CT. In total, 120 lesions were identified in 10 patients with either conventional imaging (bone scan or lesions > 1 cm on high-resolution CT, n = 69) or only with [¹⁸F]FES and [¹⁸F]FDHT PET (n = 51). All lesions were scored visually and quantitatively by two independent observers. A visually PET-positive lesion was defined as uptake above background. For quantification, we used standardised uptake values (SUV): SUV_max, SUV_peak and SUV_mean.

Results

Visual analysis showed an absolute positive and negative interobserver agreement for [¹⁸F]FES PET of 84% and 83%, respectively (kappa = 0.67, 95% CI 0.48–0.87), and 49% and 74% for [¹⁸F]FDHT PET, respectively (kappa = 0.23, 95% CI − 0.04–0.49). Intraclass correlation coefficients (ICC) for quantification of SUV_max, SUV_peak and SUV_mean were 0.98 (95% CI 0.96–0.98), 0.97 (95% CI 0.96–0.98) and 0.89 (95% CI 0.83–0.92) for [¹⁸F]FES, and 0.78 (95% CI 0.66–0.85), 0.76 (95% CI 0.63–0.84) and 0.75 (95% CI 0.62–0.84) for [¹⁸F]FDHT, respectively.

Conclusion

Visual and quantitative evaluation of [¹⁸F]FES PET showed high interobserver agreement. These results support the use of [¹⁸F]FES PET in clinical practice. In contrast, visual agreement for [¹⁸F]FDHT PET was relatively low due to low tumour-background ratios, but quantitative agreement was good. This underscores the relevance of quantitative analysis of [¹⁸F]FDHT PET in breast cancer.

Trial registration

ClinicalTrials.gov, NCT01988324. Registered 20 November 2013, https://clinicaltrials.gov/ct2/show/NCT01988324?term=FDHT+PET&draw=1&rank=2.

Observer agreement and accuracy in the evaluation of bone scans in newly diagnosed prostate cancer

OBJECTIVE

The aim of the study was to assess the agreement in the interpretation of bone scintigraphy (BS) in a newly diagnosed prostate cancer.

MATERIALS AND METHODS

A total of 635 consecutive patients had their planar whole-body BS independently reviewed by three nuclear medicine physicians and classified by two grading systems: (a) a four-category scale (1: benign; 2: equivocal; 3: most likely malignant; and 4: multiple metastases) and (b) a dichotomous scale (bone metastasis present or absent).

RESULTS

Agreement in the same category, or with one or two categories of differences, was found in 66, 34, and 1.3% of the readings, respectively. Average κ-values were 0.59, 0.72, and 0.83 for unweighted, linear, and quadratic weighted variants, respectively. Very high agreement was observed (96% of the readings) with the dichotomous scale (average κ=0.87); a comparison with a final imaging diagnosis with additional CT or MRI showed a sensitivity of 83% and a specificity of 98%. BS categories 1, 3, and 4 were consistent with the final imaging diagnosis in 96-99% of cases. The prevalence of metastasis was 10% in category 2. To optimize the diagnostic characteristics, category 2 should be regarded as a separate option.

CONCLUSION

Close agreement was found among trained observers for the evaluation of BS in prostate cancer. The high level of agreement with a dichotomous scale was hampered by diagnostic misclassification. A scale with equivocal findings on planar BS is considered important to allow for additional imaging and correct staging at the bone level of BS in a population with newly diagnosed prostate cancer.

MRI findings of new uptake in the femoral head detected on follow-up bone scans

OBJECTIVE. The purpose of this article is to suggest clinical indications for MRI in patients with breast cancer who have new uptake lesions in the femoral head on follow-up bone scans, by evaluating the incidence and causes of new uptake lesions. MATERIALS AND METHODS. Between January 2002 and July 2013, a total of 145 patients with breast cancer who showed new uptake in the femoral head on follow-up bone scans were included in our study. They were classified into two groups: group 1 consisted of 125 patients without known bone metastases, and group 2 consisted of 20 patients who already had bone metastases other than that in the femoral head. The Fisher exact test was performed for the statistical analysis. Thereafter, we reviewed MR images for characterization of the new abnormal uptake in the femoral head. RESULTS. New uptake lesions in the femoral head were metastatic in only 4.8% (6/125) of group 1 patients but in 75% (15/20) of group 2 patients (p < 0.0001). In both groups, no patient with a single uptake lesion in the femoral head had bone metastasis, whereas all patients with more than five new uptake lesions, including those of the femoral head, showed bone metastasis. Most MRI diagnoses for new uptake in the femoral head were fibrocystic change (15/30, 50%) and subchondral fracture (11/30, 36.7%). CONCLUSION. Most of the new uptake lesions in the femoral head detected on the follow-up bone scans in patients with breast cancer were benign. However, MRI could be considered in patients with known bone metastasis or with multiple new uptake lesions on bone scans.

Evaluation of image enhancement software as a method of performing half-count bone scans

Reducing the radiation dose and scanning time of diagnostic tests is often desirable. One method uses image enhancement software such as Pixon, which processes lower-count scans and aims to produce high-quality images. However, it is essential that diagnostic accuracy is not compromised. We compared the level of agreement between clinicians using standard scans, with half-count and Pixon-enhanced half-count scans. Bone scans from 150 patients referred to diagnose metastatic disease were degraded by a process of Poisson-preserving binomial resampling to generate equivalent half-count scans and then processed by Pixon software to recreate 'original' high-quality scans. Two experienced clinicians reported the scans in a randomized, blinded manner for metastatic disease (yes/no) and assigned a confidence level to this diagnosis. Levels of agreement between clinicians were calculated for the full-count, half-count, and Pixon-enhanced half-count scans and between scanning methods for each clinician. Agreement between clinicians for standard full-count scans was 92% (±4%, κ=0.80), compared with 92% (±4%, κ=0.79) for half-count scans and 87% (±5%, κ=0.70) for Pixon-processed half-count scans. Agreement for a single clinician viewing full-count versus half-count scans was 95% (±2%, κ=0.88), similar to the agreement for a single clinician viewing full-count versus Pixon-processed half-count scans (95%, ±2%, κ=0.88). With respect to confidence in diagnosis, 127 full-count scans were scored in the highest category, compared with 98 half-count and 88 Pixon-processed half-count scans. Switching to half-count scanning does not introduce more diagnostic disagreement than is already present between clinicians. However, clinicians feel less confident reporting half-count scans. The Pixon enhancement step improved neither objective diagnostic agreement nor clinician confidence.

Quality of planar whole-body bone scan interpretations--a nationwide survey

PURPOSE

The purpose of this study was to investigate, in a nationwide study, the inter-observer variation and performance in interpretations of bone scans regarding the presence or absence of bone metastases.

METHODS

Bone scan images from 59 patients with breast or prostate cancer, who had undergone scintigraphy due to suspected bone metastatic disease, were studied. The patients were selected to reflect the spectrum of pathology found in everyday clinical work. Whole body images, anterior and posterior views, were sent to all 30 hospitals in Sweden that perform bone scans. Thirty-seven observers from 18 hospitals agreed to participate in the study. They were asked to classify each of the patient studies regarding the presence of bone metastasis, using a four-point scale. Each observer's classifications were pairwise compared with the classifications made by all the other observers, resulting in 666 pairs of comparisons. The interpretations of the 37 observers were also compared with the final clinical assessment, which was based on follow-up scans and other clinical data.

RESULTS

On average, two observers agreed on 64% of the bone scan classifications. Kappa values ranged between 0.16 and 0.82, with a mean of 0.48. Sensitivity and specificity for the observers compared with the final clinical assessment were 77% and 96%, respectively, for detecting bone metastases in planar whole-body bone scanning.

CONCLUSION

Moderate inter-observer agreement was found when observers were compared pairwise. False-negative errors seem to be the major problem in the interpretations of bone scan images, whilst the specificities for the observers were high.