Imaging of bone metastasis: An update

Protocol-driven multidetector SPECT/CT: integration of hybrid imaging into the routine workflow of whole-body bone scintigraphy in oncology patients

AIM

To analyse the additional clinical value of protocol-driven and selective use of multidetector single-photon-emission tomography/computed tomography (SPECT/CT) in oncology patients undergoing whole-body bone scintigraphy (BS) and to analyse reporter confidence in diagnosis with and without SPECT/CT.

MATERIALS AND METHODS

During a 2-year period, 2,954 whole-body BS examinations were performed in oncology patients, with 444 (15%) undergoing additional protocol-driven SPECT/CT. Retrospective evaluation of planar BS and SPECT/CT images was performed by two experienced dual-trained nuclear medicine radiologists. The BS and SPECT/CT images were graded blindly using a five-point scale designed to evaluate the likelihood of a lesion being benign or malignant. Interpretation was applied on a per-patient basis.

RESULTS

There was a 74.5% increase in definitive diagnostic classification and a 26.6% reduction in equivocal findings with SPECT/CT when compared to BS alone (p<0001). Of cases initially classified as "probably benign" on BS, 5.1% (10/193) were reclassified to "probably malignant" (1%) or "malignant" (4.1%) using the SPECT/CT data. The highest impact in reporter confidence was seen with SPECT/CT in the interpretation of lesions within the pelvis (34%), ribs (23%), lumbar spine (22%), and thoracic spine (21%).

CONCLUSION

Protocol-driven, selective use of SPECT/CT imaging to augment planar BS reduces equivocal findings and improves reporter confidence whilst minimising the impact on patient and reporting workflows.

Histopathological Spectrum of Bone Changes in Skeletal Metastasis

Background: Metastatic carcinoma is the most common secondary malignant tumor affecting the bone. Bone is the third most common site for metastasis after lung and liver. The present study was planned to analyze the histomorphological patterns of bone changes in metastatic tumors and their correlation with the radiological findings. Materials and Methods: The current prospective study was conducted over a span of 2 years, encompassing 150 patients with clinically and radiologically suspected metastatic bone disease. Bone biopsy samples were studied for the pattern of bone changes. Results: Of 150 total cases, 30 cases had metastatic bone tumors. The age of the patients ranged from 37 to 84 years (mean: 57.57 ± 11.9 years). Male-to-female ratio was 2:1. All patients with metastasis presented with a complaint of pain followed by tenderness (20, 66.7%). The lesions were commonly located in the vertebral column (14, 46.7%), followed by femur (6, 20%). The primary site was known in 21 (70%) cases. The tumor histotypes were adenocarcinoma (23, 76.7%), squamous cell carcinoma (5, 16.7%), pleomorphic sarcoma (1, 3.3%), and malignant melanoma (1, 3.3%). Histomorphological patterns of bone changes were osteolytic (16, 53.3%), mixed (8, 26.7%), and osteoblastic (6, 20.0%). Correlation between the radiological findings and histopathological patterns of metastases was found to be statistically significant. Conclusions: Histomorphological assessment of bone changes in metastasis is an important parameter. Besides the histological categorization of metastatic bone disease, it plays a pivotal role in identification of the primary tumor site.

Treatment Response Assessment of Skeletal Metastases in Prostate Cancer with 18F-NaF PET/CT

PURPOSE

To determine the utility of 18F-sodium fluoride positron emission tomography-computed tomography (18F-NaF PET/CT) in the imaging assessment of therapy response in men with osseous-only metastatic prostate cancer.

METHODS

In this Institutional Review Board-approved single institution retrospective investigation, we evaluated 21 18F-NaF PET/CT scans performed in 14 patients with osseous metastatic disease from prostate cancer and no evidence of locally recurrent or soft-tissue metastatic disease who received chemohormonal therapy. Imaging-based qualitative and semi-quantitative parameters were defined and compared with changes in serum PSA level.

RESULTS

Qualitative and semi-quantitative image-based assessments demonstrated > 80% concordance with good correlation (SUVmax κ = 0.71, SUVavg κ = 0.62, SUVsum κ = 0.62). Moderate correlation (κ = 0.43) was found between SUVmax and PSA-based treatment response assessments. There was no statistically significant correlation between PSA-based disease progression and semi-quantitative parameters. Qualitative imaging assessment was moderately correlated (κ = 0.52) with PSA in distinguishing responders and non-responders.

CONCLUSION

18F-NaF PET/CT is complementary to biochemical monitoring in patients with bone-only metastases from prostate cancer which can be helpful in subsequent treatment management decisions.

Measuring the unmeasurable: automated bone scan index as a quantitative endpoint in prostate cancer clinical trials

BACKGROUND

Up to 90% of men with metastatic castration-resistant prostate cancer (mCRPC) will have a distribution of disease that includes bone metastases demonstrated on a Technetium-99m (^99mTc-MDP) bone scan. The Prostate Cancer Working Group 2 and 3 Consensus Criteria standardized the criteria for assessing progression based on the development of new lesions. These criteria have been recognized by regulatory authorities for drug approval. The bone scan index (BSI) is a method to quantitatively measure the burden of bony disease, and can assess both disease progression and regression. The automated BSI (aBSI) is a method of computer analysis to assess BSI, and is being qualified as a clinical trials endpoint.

METHODS

Manual searching was used to identify the literature on BSI and aBSI. We summarize the most relevant aspects of the retrospective and prospective studies evaluating aBSI measurements, and provide a critical discussion on the potential advantages and caveats of aBSI.

RESULTS

The development of neural artificial networks (EXINI boneBSI) to automatically determine the BSI reduces the turnaround time for assessing BSI with high reproducibility and accuracy. Several studies showed that the concordance between aBSI and BSI, as well as the interobserver concordance of aBSI, was >0.95. In a phase 3 assessment of aBSI, a doubling value increased the risk of death in 20%, pre-treatment aBSI values independently correlated with overall survival (OS) and time to symptomatic progression. Retrospective studies suggest that a decrease in aBSI after treatment may correlate with higher survival when compared with increasing aBSI.

CONCLUSIONS

aBSI provides a quantitative measurement that is feasible, reproducible, and in analyses to date correlates with OS and symptomatic progression. These findings support the aBSI to risk-stratify men with mCRPC for clinical trial enrollment. Future studies quantifying aBSI change over time as an intermediate endpoint for evaluating new systemic therapies are needed.

Downstream Studies Following the Use of Bone Scan in the Staging of Muscle-invasive Bladder Cancer

OBJECTIVE

To quantify the use of downstream studies following staging bone scans in patients with muscle-invasive bladder cancer. Bone scans may be obtained in high-risk bladder cancer patients prior to radical cystectomy to exclude bone metastases. However, false-positive bone scans can occur, resulting in the need for additional studies.

PATIENTS AND METHODS

Using Surveillance, Epidemiology, and End Results (SEER)-Medicare data, we identified 4404 patients diagnosed with muscle-invasive bladder cancer from 2004 to 2011. We further identified those who underwent a bone scan prior to treatment within 6 months of diagnosis and prior to any treatment with cystectomy, radiotherapy, or chemotherapy. We determined the proportion of patients who underwent a subsequent study (bone X-ray, bone CT, bone MRI, and/or bone biopsy) within 3 months of the bone scan and prior to treatment.

RESULTS

Among patients diagnosed with muscle-invasive bladder cancer, 1373 (31%) had a staging bone scan of whom 26% received a downstream study (n = 213). Overall, 61 patients (7%) received downstream bone-specific X-rays, more than 141 patients (>17%) received bone-specific CTs, and 28 patients (3%) received bone-specific MRIs. The use of bone biopsy was rare (n < 11; <1%). The total cost of all downstream studies was $103,468. Furthermore, there was a one-month delay in treatment for those who received a downstream study compared to those who did not (P < 0.001).

CONCLUSION

Use of bone scan in the staging of muscle-invasive bladder cancer often results in the need for additional downstream studies. The delay in treatment and cost burden of downstream studies highlights a potential disadvantage of the routine use of this staging modality.

Preliminary results of biodistribution and dosimetric analysis of [68Ga]Ga-DOTAZOL: a new zoledronate-based bisphosphonate for PET/CT diagnosis of bone diseases

OBJECTIVE

Pre-clinical studies with gallium-68 zoledronate ([⁶⁸Ga]Ga-DOTA^ZOL) have proposed it to be a potent bisphosphonate for PET/CT diagnosis of bone diseases and diagnostic counterpart to [¹⁷⁷Lu]Lu-DOTA^ZOL and [²²⁵Ac]Ac-DOTA^ZOL. This study aims to be the first human biodistribution and dosimetric analysis of [⁶⁸Ga]Ga-DOTA^ZOL.

METHODS

Five metastatic skeletal disease patients (mean age: 72 years, M: F; 4:1) were injected with 150-190 MBq (4.05-5.14 mCi) of [⁶⁸Ga]Ga-DOTA^ZOL i.v. Biodistribution of [⁶⁸Ga]Ga-DOTA^ZOL was studied with PET/CT initial dynamic imaging for 30 min; list mode over abdomen (reconstructed as six images of 300 s) followed by static (skull to mid-thigh) imaging at 45 min and 2.5 h with Siemens Biograph 2 PET/CT camera. Also, blood samples (8 time points) and urine samples (2 time points) were collected over a period of 2.5 h. Total activity (MBq) in source organs was determined using interview fusion software (MEDISO Medical Imaging Systems, Budapest, Hungary). A blood-based method for bone marrow self-dose determination and a trapezoidal method for urinary bladder contents residence time calculation were used. OLINDA/EXM version 2.0 software (Hermes Medical Solutions, Stockholm, Sweden) was used to generate residence times for source organs, organ absorbed doses and effective doses.

RESULTS

High uptake in skeleton as target organ, kidneys and urinary bladder as organs of excretion and faint uptake in liver, spleen and salivary glands were seen. Qualitative and quantitative analysis supported fast blood clearance, high bone to soft tissue and lesion to normal bone uptake with [⁶⁸Ga]Ga-DOTA^ZOL. Urinary bladder with the highest absorbed dose of 0.368 mSv/MBq presented the critical organ, followed by osteogenic cells, kidneys and red marrow receiving doses of 0.040, 0.031 and 0.027 mSv/MBq, respectively. The mean effective dose was found to be 0.0174 mSv/MBq which results in an effective dose of 2.61 mSv from 150 MBq.

CONCLUSIONS

Biodistribution of [⁶⁸Ga]Ga-DOTA^ZOL was comparable to [¹⁸F]NaF, [^99mTc]Tc-MDP and [⁶⁸Ga]Ga-PSMA-617. With proper hydration and diuresis to reduce urinary bladder and kidney absorbed doses, it has clear advantages over [¹⁸F]NaF owing to its onsite, low-cost production and theranostic potential of personalized dosimetry for treatment with [¹⁷⁷Lu]Lu-DOTA^ZOL and [²²⁵Ac]Ac-DOTA^ZOL.

Diagnosis of metastasis in castration-resistant prostate cancer patients: decision algorithm in imaging tests

INTRODUCTION

In castration-resistant prostate cancer (CRPC), early detection of metastases is essential for the selection of treatment, and prevention of bone complications. However detecting incipient metastases remains a challenge as the conventional radiological tests (bone scintigraphy or computerised tomography) lack sufficient sensitivity. Diagnostic imaging techniques are currently available that have greater sensitivity and specificity, but are little used due to shortfalls in the recommendations.

OBJECTIVE

To create an algorithm that indicates the most suitable diagnostic imaging techniques for the different M0 CRPC patient profiles based on the scientific evidence.

EVIDENCE ACQUISITION

Meetings were held with eight experts in Urology, Pathological Anatomy, Radiodiagnostics and Nuclear Medicine organised by the Andalusian Association of Urology, in which the recommendations and scientific evidence on each of the diagnostic imaging techniques were reviewed.

SUMMARY OF THE EVIDENCE

We present the current recommendations for the detection of metastasis in M0 CRPC patients, the patients that would benefit from early detection, and summarise the evidence to support the use of each of the new techniques.

CONCLUSIONS

Techniques such as ¹⁸F-Choline PET/CT or DWWB MRI and probably open MRI have been demonstrated to have good sensitivity and specificity for patients with low PSA (<10ng/ml). Their inclusion in routine clinical practice will help improve the early detection of metastasis in CRPC patients.

Challenges in the Diagnosis of bone Metastasis in Patients without a History of Malignancy at Their First Clinic Visit

BACKGROUND

Many patients with bone metastases whose diagnoses came only after they had suffered aggravated conditions are still frequently encountered. However, there have been few studies regarding the early diagnosis of such metastases. We retrospectively reviewed the clinical courses of cases we experienced between 2004 and 2014 to clarify the practical situation of diagnosis of such bone metastases.

METHODS

We undertook a retrospective review of 56 of our patients with bone metastasis who had no history of malignancy at their first visit, who visited our departments between 2004 and 2014. The initial diagnoses at the first visit to any clinic, the period from the first visit to any clinic to diagnosis of bone metastasis, the process to make the diagnosis, the frequency of severe skeletal-related events at diagnosis, and the examination serving as the basis for diagnosis were evaluated.

RESULTS

The diagnosis of bone metastasis was made at the first visit in only 6 of the 56 patients. Pathological fractures, paralysis and/or calcemia were seen in 62.5% of the patients at diagnosis of bone metastasis. The median period from the first visit to any clinic to diagnosis was 7.0 weeks. Typically, the diagnosis of bone metastasis was made only after aggravation. The most frequent examination to serve as the basis of diagnosis was magnetic resonance imaging.

CONCLUSIONS

Diagnosis of bone metastasis is challenging in patients without a history of malignancy at their first visit. For early diagnosis, it is important to recognize this challenge and to keep it in mind together with ongoing observation.

Coexistence of giant cell tumor of tendon sheath and enchondroma in the middle phalanx of the little finger mimicking a malignant tumor: A case report

Giant cell tumor of the tendon sheath is a type of slow-growing benign soft tissue tumor that typically arises from the synovium of the tendon sheath. Enchondroma is a benign bone tumor comprising of mature hyaline cartilage that centrally develops within the tubular bone. While giant cell tumor of the tendon sheath or enchondroma are common benign soft tissue and bone tumors, respectively the simultaneous occurrence of these tumors in the same region of the hand is exceedingly rare, and it can mimic a malignant tumor, thereby making the diagnosis more challenging. Herein, we report an unusual imaging presentation of the coexistence of these tumors in the middle phalanx of the little finger, which to the best of our knowledge has not been previously reported, and this initially present as a single intrinsic osseous lesion mimicking malignancy. The coexistence of these tumor types must be considered in the differential diagnosis of an intramedullary lytic lesion with a poor margin associated with a soft tissue mass of the fingers, and a meticulous preoperative magnetic resonance imaging investigation was required.

Evaluating radium-223 response in metastatic castration-resistant prostate cancer with imaging

Radium-223 is a first-in-class targeted alpha therapy indicated for treating bone metastases from metastatic castration-resistant prostate cancer (mCRPC) without visceral metastases. Imaging plays an important role in the selection of patients eligible for radium-223 therapy. In the ALSYMPCA trial protocol, bone scintigraphy was used to detect lesions, essentially osteoblastic bone metastases, whereas computed tomography (CT) was used to exclude visceral metastases, with no interim imaging until treatment completion unless clinically indicated. Yet, questions remain: How can we monitor treatment progress more closely and evaluate treatment response more precisely? In the cases discussed herein, interim evaluation of response to radium-223 showed discordance between bone scintigraphy and ¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the patterns of bone lesions observed, that is more lesions were detected on PET/CT. It is postulated that the additional lesions may be attributed to bone marrow metastases that were not effectively targeted by radium-223 as its alpha radiation do not reach deep into the bone marrow. Although the clinical significance of the discordance requires further clarification, it makes sense to consider radium-223 early on in the course of mCRPC, when marrow involvement is minimal, so as to optimize treatment outcomes.

A pathological toe fracture as the first presentation of cervical cancer: A case report

RATIONALE

Cervical cancer is one of the most common gynecologic malignancies worldwide, and it spreads mainly through direct extension. Distinct metastases are less common and usually spread to distant lymph nodes, lungs, and bones. Bone metastases from cervical cancer are most commonly observed in the pelvis and spine. Thus, a pathological toe fracture as the initial presentation of cervical cancer is extremely rare.

PATIENT CONCERNS

We report a patient with a toe metastasis that first presented with pain caused by a pathological fracture.

DIAGNOSES

The patient underwent surgery to remove the right great toe, and the histopathology revealed squamous carcinoma that originated from the cervix.

INTERVENTIONS

The patient then underwent cervical cancer surgery, chemotherapy, and radiotherapy.

LESSONS

A pathological toe fracture as the initial presentation of cervical cancer is extremely rare, but clinicians need to be aware that we should not exclude cancer when patients come to the hospital for pathological fractures.

Mazabraud's Syndrome: A Case Report and Up-To-Date Literature Review

OBJECTIVE

Mazabraud's syndrome is a rare form of bone fibrous dysplasia associated with intramuscular myxomas. Fibrous dysplasia, is generally localized to pelvis and femur and it results in a fragile bone with deformities, pain, pathological fractures and functional impairment. Intramuscular myxomas, are rare benign mesenchymal neoplasms that exceptionally may evolve to malignant forms.

METHODS

This case report describes a 66-year-old woman with Mazabraud's Syndrome (MS), characterized both by monostotic right femur fibrous dysplasia and by a solitary intramuscular myxoma at the right quadriceps muscle, that underwent a long-term treatment (4 years) with intravenous zoledronic acid.

RESULTS

Zoledronic acid therapy rapidly lowered bone pain together with a reduction of intramuscular myxoma volume, but did not affect the extension of fibrous dysplasia. No adverse effects have been observed during treatment.

CONCLUSION

Highly active bisphosphonates are commonly used for the treatment of bone metabolic disorders and they are generally well tolerated. Zoledronic acid may represent a promising alternative to surgical intervention in MS, although its use in rare form of bone fibrous dysplasias is still controversial.

Diagnostic Value of Plain Radiography for Symptomatic Bone Metastasis at the First Visit

BACKGROUND

To prevent and minimize skeletal-related diseases, early diagnosis of bone metastases is important. However, previous reports have shown that plain radiography has low sensitivity and fails to screen multiple asymptomatic lesions. Limited investigations have been reported on the value of plain radiography in the diagnosis of symptomatic bone metastases. Therefore, this study aimed to investigate the diagnostic utility of plain radiography for symptomatic bone metastasis.

METHODS

Two experienced orthopedic surgeons retrospectively evaluated the plain radiographs of 39 patients with symptoms during their first visit between 2011 and 2014 for bone metastases. Another 2 experienced orthopedic surgeons then reviewed the data using 2 reference standards, the clinical results and the retrospectively evaluated results, in a blinded manner. The data were then reviewed by 2 certified orthopedic surgeons and 7 orthopedic surgeons in training with differing years of experience in a blinded manner.

RESULTS

The overall sensitivity of diagnosis of symptomatic bone metastasis using plain radiography at the clinic first visit was 71.4%. Upon blinded evaluation, the accuracy, sensitivity, and specificity were 55.8%, 54.3%, and 68.8% and 77.6%, 73.0%, and 85.7% for clinical results and results from 2 experienced orthopedic surgeons as a reference standard, retrospectively. There was a strong and significant correlation between the accuracy and observers' years of experience in orthopedic surgery among the orthopedic surgeons in training (R=0.942, p=0.0015).

CONCLUSIONS

Plain radiography around the time of the first visit has a definitive role in the early diagnosis of symptomatic bone metastasis.

Whole-body magnetic resonance imaging for the assessment of metastatic breast cancer

Breast cancer is the most common type of tumor in women and an important cause of mortality in the female population. The early and precise diagnosis, staging, and treatment of this neoplasia are essential for public health purposes. Technological development, for example, of whole-body magnetic resonance imaging, made possible the adoption of new imaging modalities for a better approach for these patients. This imaging modality is helpful to staging, to therapy response assessment, and to the study of therapeutic changes in bone marrow, because it gives, at the same time, anatomical information using T1- and T2-weighted images, with high spatial resolution and tissue contrast, as well as functional sequences (diffusion-weighted images), which make possible the detection of hypercellular viable tumors.

Quantification of bone flare on 18F-NaF PET/CT in metastatic castration-resistant prostate cancer

BACKGROUND

Bone flare has been observed on ^99mTc-MDP bone scans of patients with metastatic castration-resistant prostate cancer (mCRPC). This exploratory study investigates bone flare in mCRPC patients receiving androgen receptor (AR) inhibitors using ¹⁸F-NaF PET/CT.

METHODS

Twenty-nine mCRPC patients undergoing AR-inhibiting therapy (abiraterone, orteronel, enzalutamide) received NaF PET/CT scans at baseline, week 6, and week 12 of treatment. SUV metrics were extracted globally for each patient (SUV) and for each individual lesion (iSUV). Bone flare was defined as increasing SUV metrics or lesion number at week 6 followed by subsequent week 12 decrease. Differences in metrics across timepoints were compared using Wilcoxon tests. Cox proportional hazard regression was conducted between global metrics and progression-free survival (PFS).

RESULTS

Total SUV was most sensitive for flare detection and was identified in 14/23 (61%) patients receiving CYP17A1-inhibitors (abiraterone, orteronel), and not identified in any of six patients receiving enzalutamide. The appearance of new lesions did not account for initial increases in SUV metrics. iSUV metrics followed patient-level trends: bone flare positive patients showed a median of 72% (range: 0-100%) of lesions with total iSUV flare. Increasing mean SUV at week 6 correlated with extended PFS (HR = 0.58, p = 0.02).

CONCLUSION

NaF PET bone flare was present on 61% of mCRPC patients in the first 6 weeks of treatment with CYP17A1-inhibitors. Characterization provided in this study suggests favorable PFS in patients showing bone flare. This characterization of NaF flare is important for guiding treatment assessment schedules to better distinguish between patients showing bone flare and those truly progressing, and should be performed for all emerging mCRPC treatments and imaging agents.

Diagnostic Performance of 18F-Fluciclovine in Detection of Prostate Cancer Bone Metastases

PURPOSE

F-fluciclovine is a synthetic amino acid radiotracer that has recently been approved in Europe and the United States for PET imaging in men with biochemical recurrence (BCR) of prostate cancer after prior definitive treatment. Accurate identification of the sites of disease in patients presenting with BCR of prostate cancer is important in determining the appropriate treatment. Bone is the most frequent site of metastatic disease in patients with prostate cancer.

METHODS

We conducted a comprehensive review of the available preclinical and clinical data on the diagnostic performance of F-fluciclovine PET/CT in an attempt to draw practical and general conclusions on the utility and limitations of F-fluciclovine PET/CT in localization of osseous metastatic disease in prostate cancer.

RESULTS

The cumulative preclinical data and results of some retrospective and 2 prospective clinical studies suggest that F-fluciclovine can detect early bone marrow involvement in patients with BCR of prostate cancer and negative prior bone-specific imaging findings.

CONCLUSIONS

F-fluciclovine PET/CT seems to offer useful information for early detection of bone metastases in men with BCR of prostate cancer. Additional investigations will be needed to compare the diagnostic performance of F-fluciclovine PET/CT to other standard and novel imaging methods in initial staging, BCR, and castrate-resistant phases of disease.

A Rare Case of Spinal Sarcoidosis Presenting as Multiple Bone Marrow Oedematous Lesions

Sarcoidosis is a systemic disorder that most commonly affects the lungs. Bone involvement is rare, and spinal involvement is even more rare. The presence of focal lesions of the vertebrae is highly suspicious of advanced malignancy. However, malignant metastatic spread to the spine involves the vertebral cortex rather than the bone marrow itself, a distinction that is often missed and therefore misleading. We describe here a middle-aged woman with multiple focal oedematous lesions of the bone marrow suspected of being advanced malignancy but finally diagnosed as a rare case of spinal sarcoidosis.

Accuracy of Opposed-phase Magnetic Resonance Imaging for the Evaluation of Treated and Untreated Spinal Metastases

RATIONALE AND OBJECTIVES

To assess whether the accuracy of opposed-phase magnetic resonance (MR) imaging to differentiate spinal metastases from benign lesions is influenced by treatment.

MATERIALS AND METHODS

We retrospectively evaluated 25 benign lesions, 25 untreated spinal metastases, and 89 treated spinal metastases in 101 patients who underwent opposed-phase MR spine imaging at our institution. The largest possible region of interest was placed over the lesion in question on out-of-phase and in-phase MR sequences, and the signal intensity ratio (SIR) of the lesions was calculated. The SIRs were compared between benign, untreated, and treated lesions. Receiver operator characteristic (ROC) curves were used to identify the optimal threshold to differentiate benign lesions from untreated spinal metastases, and the accuracy of this threshold was assessed for treated spinal metastases, chemotherapy-treated spinal metastases, and radiated spinal metastases.

RESULTS

Benign lesions had lower mean SIR than untreated (P = 2.4 × 10^-8, 95% confidence interval [0.29, 0.51]) and treated spinal metastases (P = .51; 95% confidence interval [-0.13, 0.06]). A cutoff SIR of 0.856 had an accuracy of 88.00% for untreated lesions, 77.48% for previously treated lesions, and 70.45% for previously radiated lesions. The ROC curve to differentiate benign lesions from radiated spinal metastases was significantly different from the ROC curve to differentiate benign lesions from untreated spinal metastases (P = .0180). The ROC curve to differentiate benign lesions from lesions treated with chemotherapy only was significantly different from the ROC curve to differentiate between benign lesions and radiated spinal metastases (P = .041).

CONCLUSIONS

Opposed-phase imaging is less accurate for treated spinal metastases, in particular after radiation.

Circulating tumor DNA as prognostic markers for late stage NSCLC with bone metastasis

PURPOSE

Bone metastases from non-small cell lung cancer (NSCLC) are common, and current prognostic stratification methods are challenging to predict outcomes. The aim of the study is to examine circulating tumor DNA as a potential biomarker to gauge overall survival.

METHODS

Late stage NSCLC patients associated with bone metastasis were recruited for the study. Circulating tumor DNA was quantified using droplet digital polymerase chain reaction, a sensitive assay that is capable to pick up low mutant DNA frequencies. KRAS and EGFR genes were serially profiled at monthly intervals to ascertain their variations in different patients during monitoring. These were correlated to overall survival as an endpoint measure.

RESULTS

Analysis of circulating tumor DNA and tumor tissues samples yielded a 94.7% overall agreement for KRAS and EGFR mutations. Higher circulating tumor DNA quantities of more than 1.4-fold were also detected in patients with bone metastases. To gauge the prognostic utility of circulating tumor DNA for these patient groups, circulating tumor DNA quantities as well as the patients' genotypes were used to stratify patients in the survival analysis. Hazard ratios for patient groups with and without bone metastasis was 1.63. Patients groups separated by circulating tumor DNA quantity and molecular profile were 1.51 and 1.58, respectively. The results showed that circulating tumor DNA was a useful marker to identify patients with better survival outcomes.

CONCLUSION

The good overall concordance in genetic profiling and circulating tumor DNA measurements associated with NSCLC patients with bone metastases supports plasma-based testing. This study presents exploratory evidence of the prognostic role of circulating tumor DNA that can be of value in the management of the disease.

Peering beneath the surface: juxtacortical tumors of bone (part II)

Juxtacortical or surface tumors of bone are neoplasms arising from or just outside the cortex, and are composed of different histologic types. Although the imaging appearances of these lesions have similarities to their intramedullary counterparts, their location alters their radiographic and MR characteristics, creating difficulties in diagnosis. Meanwhile, several non-neoplastic lesions, such as stress reaction/stress fracture and indolent infectious processes, compound the differential diagnosis. Neoplastic juxtacortical lesions of bone have been classified into five categories: cartilaginous, fibrous, lipomatous, osseous, and metastatic tumors. Our goal in part two of this review is to illustrate the characteristic radiographic, CT and MR imaging features of various juxtacortical neoplasms, including pathognomonic imaging findings that can aid in diagnosis, and to develop an appropriate differential diagnosis for surface lesions based on imaging characteristics, lesion location and patient age.

Diagnostic value of additional 68Ga-PSMA-PET before 223Ra-dichloride therapy in patients with metastatic prostate carcinoma

Purpose: Medical imaging plays an important role in selecting patients with metastatic castration-resistant prostate cancer for 223Ra- dichloride therapy of bone metastases. The purpose of this study was to investigate whether 68Ga-PSMA-PET has incremental value over conventional imaging for selecting patients suitable for 223Ra-dichloride therapy. Methods: In 27 consecutive patients referred for 223Ra-dichloride therapy additional 68Ga-PSMA-PET/CT was performed and tracer distribution was evaluated systematically with respect to the detection of visceral metastases and bone metastases with inadequate uptake on bone scintigraphy. Results: In 4 patients (15 %) 68Ga- PSMA-PET revealed previously unknown visceral metastases (3 liver, 1 adrenal gland), which changed the therapeutic decision in 2 cases. PET revealed more extended tumour involvement in the bone compared to bone scintigraphy in 9 patients (33 %). In 3 of these, the mismatch was extensive enough to question suitability for 223Ra-dichloride therapy. Conclusions: Additional 68Ga-PSMA-PET as a gatekeeper between conventional staging and 223Ra-dichloride therapy can provide valuable additional information with regard to visceral metastases and tumour manifestations without adequate bone mineral turnover. It may lead to a change in therapeutic management in a significant number of patients and should therefore be considered in future clinical trials.

Prognostic utility of FDG PET/CT and bone scintigraphy in breast cancer patients with bone-only metastasis

We performed this retrospective clinical study to examine the prognostic power of bone scintigraphy (BS) and F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in terms of overall survival (OS) of breast cancer with bone-only metastasis.We retrospectively evaluated 100 female invasive ductal breast cancer patients (mean age 48.1 years) with bone-only metastasis. Twenty-five patients had human epidermal growth factor receptor 2 (HER2)-positive tumors, 65 were estrogen receptor (ER) and/or progesterone receptor (PR)-positive, HER2-negative tumors, and 10 were triple negative tumors. The patients were treated properly with various treatments, including chemotherapy, radiotherapy, hormone, and bisphosphonate therapy, based on their clinical status. All patients underwent BS and FDG PET/CT at baseline and 1 year after treatment. The baseline and follow images were visually compared, and the patients were grouped as responders or nonresponders based on their images. OS was compared between the groups.The mean OS after the diagnosis of bone-only metastasis was 57.6 months. Fifty-one patients (51%) died within 5 years after diagnosis of metastasis. No difference in survival was evident between responders and nonresponders based on BS imaging data (P = .090). The response status based on PET imaging data waste only significant independent prognostic factor on multivariate analysis (P = .001). Survival was lower in nonresponders than in responders based on PET imaging (32.7% vs 66.4%; P < .001).Our findings suggest that the response status according to FDG PET imaging can be used to predict OS in breast cancer patients with bone-only metastasis.

Pseudolesions Impersonating Osseous Tumor Involvement on Both Contrast Enhanced CT and FDG PET/CT

A 27-year-old man with stage IV-B Hodgkin's lymphoma status post autologous peripheral stem cell transplant in 2015 with complete response, presented in 2017 with increasing back pain. Restaging contrast enhanced CT demonstrated left brachiocephalic vein occlusion with peripheral nodular high density areas within C7-T2 vertebral bodies with corresponding radiotracer uptake on same day PET/CT. No matching lesion was seen on noncontrast CT. Findings were consistent with pooling of contrast and radiotracer within vertebral venous plexus collaterals at the cervicothoracic junction secondary to brachiocephalic vein occlusion. Repeat PET/CT with contralateral injection of radiotracer and MRI confirmed absence of osseous lymphomatous involvement.

Early identification and intervention matters: A comprehensive review of current evidence and recommendations for the monitoring of bone health in patients with cancer

Bone metastases are common in patients with advanced solid tumors, and many individuals experience debilitating skeletal-related events (SREs; e.g. pathologic fracture, hypercalcemia, radiotherapy or surgery to bone, and spinal cord compression). These events substantially affect disease outcomes, including survival and quality of life, and healthcare systems. Plain radiography is the most widely used imaging modality for the detection of bone metastases; skeletal scintigraphy, computed tomography, positron emission tomography and magnetic resonance imaging offer greater sensitivity but their use in routine practice is restricted by high costs and limited availability. Biomarkers of bone turnover may also have a role in the early detection of bone metastases and can provide valuable prognostic information on disease progression. SREs can be delayed or prevented using agents such as the receptor activator of nuclear factor kappa B ligand (RANKL) inhibitor, denosumab, and bisphosphonates. Painful bone metastases can be treated with radiofrequency ablation, radiotherapy, or radionuclides such as radium-223 dichloride, which has been shown to delay the onset of SREs in men with castration-resistant prostate cancer. Close monitoring of bone health in patients with advanced cancer may lead to early identification of individuals with bone metastases who could benefit from early intervention to prevent SREs. This review examines current guideline recommendations for assessing and monitoring bone health in patients with advanced cancer, use of biomarkers and treatment of patients with bone metastases. The emerging evidence for the potential survival benefit conferred by early intervention with denosumab and bisphosphonates is also discussed, together with best practice recommendations.

Chapter 4 Thyroid Malignancy: Staging and Restaging

Determining the extent of disease is necessary for guiding the management of thyroid carcinomas. Diagnostic imaging, including ultrasound, computed tomography, magnetic resonance imaging, and nuclear medicine scans, plays an essential role in staging and restaging of thyroid carcinomas. This article reviews the approaches and imaging findings for evaluating the primary tumor, regional lymph node metastases, and distant metastases. In addition, potential pitfalls are discussed and depicted.

Quantitative contrast-enhanced CT attenuation evaluation of osseous metastases following chemotherapy

PURPOSE

Osseous metastases often undergo an osteoblastic healing response following chemotherapy. The purpose of our study was to demonstrate the quantitative CT changes in attenuation of osseous metastases before and after chemotherapy.

MATERIALS AND METHODS

Our study was IRB approved and HIPAA compliant. Our cohort consisted of 86 consecutive cancer patients with contrast-enhanced CTs before and 14 ± 2 (12-25) months after initiation of chemotherapy (60 ± 11 years, 36 males, 50 females). The average and maximum metastasis attenuations were measured in Hounsfield units (HU) by two readers. Treatment effects were assessed using paired t-tests and Fisher exact tests. Intraclass correlation coefficients (ICCs) were calculated. Patient records were reviewed to determine the patient's clinical status (worse, unchanged, or improved) at the time of follow-up CT.

RESULTS

The distribution of lesion types was as follows: lytic (30/86, 35%), blastic (43/86, 50%), and mixed lytic-blastic (13/86, 15%). There was a significant increase in average and maximum CT attenuation of metastases following chemotherapy for all patients, which remained statistically significant when stratified by lesion type, clinical status (worsening or improving/stable), cancer type (breast, lung), and radiation therapy (P < 0.05). In a subgroup of patients whose osseous metastases decreased in average attenuation (14/86, 16%), more patients had a worse clinical status (11/14, 79%) (P = 0.02). ICC was almost perfect for average attenuation and substantial for maximum attenuation.

CONCLUSION

Quantitative assessment of osseous metastatic disease using CT attenuation measurements demonstrated a statistically significant increase in attenuation more than 12 months after initiation of chemotherapy.

Inter-observer agreement in GTV delineation of bone metastases on CT and impact of MR imaging: A multicenter study

BACKGROUND AND PURPOSE

The use of Stereotactic Body Radiotherapy (SBRT) for bone metastases is increasing rapidly. Therefore, knowledge of the inter-observer differences in tumor volume delineation is essential to guarantee precise dose delivery. The aim of this study is to compare inter-observer agreement in bone metastases delineated on different imaging modalities.

MATERIAL AND METHODS

Twenty consecutive patients with bone metastases treated with SBRT were selected. All patients received CT and MR imaging in treatment position prior to SBRT. Five observers from three institutions independently delineated gross tumor volume (GTV) on CT alone, CT with co-registered MRI and MRI alone. Four contours per imaging modality per patient were available, as one set of contours was shared by 2 observers. Inter-observer agreement, expressed in generalized conformity index [CIgen], volumes of contours and contours center of mass (COM) were calculated per patient and imaging modality.

RESULTS

Mean GTV delineated on MR (45.9±52.0cm³) was significantly larger compared to CT-MR (40.2±49.4cm³) and CT (34.8±41.8cm³). A considerable variation in CIgen was found on CT (mean 0.46, range 0.15-0.75) and CT-MRI (mean 0.54, range 0.17-0.71). The highest agreement was found on MRI (mean 0.56, range 0.20-0.77). The largest variations of COM were found in anterior-posterior direction for all imaging modalities.

CONCLUSIONS

Large inter-observer variation in GTV delineation exists for CT, CT-MRI and MRI. MRI-based GTV delineation resulted in larger volumes and highest consistency between observers.

Real-time in vivo imaging of metastatic bone tumors with a targeted near-infrared fluorophore

Tumors of the prostate or breast are particularly likely to metastasize to the bone, and early diagnosis of metastatic bone tumors is important for designing an effective treatment strategy. Imaging modalities for the detection of bone metastasis are limited, and radiation-based techniques are commonly used. Here, we investigated the efficacy of selective near-infrared (NIR) fluorescence detection of metastatic bone tumors and its role in the detection of bone metastasis in prostate and breast cancer cell lines and in a xenograft mouse model. A targeted NIR fluorophore was used to monitor metastatic bone tumors using a NIR fluorescence imaging system in real time, enabling the diagnosis of bone metastasis in vivo by providing the location of the metastatic bone tumor. The NIR fluorescence imaging technique using targeted NIR contrast agents is a potential tool for the early diagnosis of bone tumors.

Optimization and In Vivo Profiling of a Refined Rat Model of Walker 256 Breast Cancer Cell-Induced Bone Pain Using Behavioral, Radiological, Histological, Immunohistochemical and Pharmacological Methods

In the majority of patients with advanced breast cancer, there is metastatic spread to bones resulting in pain. Clinically available drug treatments for alleviation of breast cancer-induced bone pain (BCIBP) often produce inadequate pain relief due to dose-limiting side-effects. A major impediment to the discovery of novel well-tolerated analgesic agents for the relief of pain due to bony metastases is the fact that most cancer-induced bone pain models in rodents relied on the systemic injection of cancer cells, causing widespread formation of cancer metastases and poor general animal health. Herein, we have established an optimized, clinically relevant Wistar Han female rat model of breast cancer induced bone pain which was characterized using behavioral assessments, radiology, histology, immunohistochemistry and pharmacological methods. In this model that is based on unilateral intra-tibial injection (ITI) of Walker 256 carcinoma cells, animals maintained good health for at least 66 days post-ITI. The temporal development of hindpaw hypersensitivity depended on the initial number of Walker 256 cells inoculated in the tibiae. Hindpaw hypersensitivity resolved after approximately 25 days, in the continued presence of bone tumors as evidenced by ex vivo histology, micro-computed tomography scans and immunohistochemical assessments of tibiae. A possible role for the endogenous opioid system as an internal factor mediating the self-resolving nature of BCIBP was identified based upon the observation that naloxone, a non-selective opioid antagonist, caused the re-emergence of hindpaw hypersensitivity. Bolus dose injections of morphine, gabapentin, amitriptyline and meloxicam all alleviated hindpaw hypersensitivity in a dose-dependent manner. This is a first systematic pharmacological profiling of this model by testing standard analgesic drugs from four important diverse classes, which are used to treat cancer induced bone pain in the clinical setting. Our refined rat model more closely mimics the pathophysiology of this condition in humans and hence is well-suited for probing the mechanisms underpinning breast cancer induced bone pain. In addition, the model may be suitable for efficacy profiling of new molecules from drug discovery programs with potential to be developed as novel agents for alleviation of intractable pain associated with disseminated breast cancer induced bony metastases.

Bone scintigraphy in patients with pain

Nuclear medicine imaging is widely used in pain medicine. Low back pain is commonly encountered by physicians, with its prevalence from 49% to 70%. Computed tomography (CT) or magnetic resonance imaging (MRI) are usually used to evaluate the cause of low back pain, however, these findings from these scans could also be observed in asymptomatic patients. Bone scintigraphy has an additional value in patients with low back pain. Complex regional pain syndrome (CRPS) is defined as a painful disorder of the extremities, which is characterized by sensory, autonomic, vasomotor, and trophic disturbances. To assist the diagnosis of CRPS, three-phase bone scintigraphy is thought to be superior compared to other modalities, and could be used to rule out CRPS due to its high specificity. Studies regarding the effect of bone scintigraphy in patients with extremity pain have not been widely conducted. Ultrasound, CT and MRI are widely used imaging modalities for evaluating extremity pain. However, SPECT/CT has an additional role in assessing pain in the extremities.

A multi-resolution approach for spinal metastasis detection using deep Siamese neural networks

Spinal metastasis, a metastatic cancer of the spine, is the most common malignant disease in the spine. In this study, we investigate the feasibility of automated spinal metastasis detection in magnetic resonance imaging (MRI) by using deep learning methods. To accommodate the large variability in metastatic lesion sizes, we develop a Siamese deep neural network approach comprising three identical subnetworks for multi-resolution analysis and detection of spinal metastasis. At each location of interest, three image patches at three different resolutions are extracted and used as the input to the networks. To further reduce the false positives (FPs), we leverage the similarity between neighboring MRI slices, and adopt a weighted averaging strategy to aggregate the results obtained by the Siamese neural networks. The detection performance is evaluated on a set of 26 cases using a free-response receiver operating characteristic (FROC) analysis. The results show that the proposed approach correctly detects all the spinal metastatic lesions while producing only 0.40 FPs per case. At a true positive (TP) rate of 90%, the use of the aggregation reduces the FPs from 0.375 FPs per case to 0.207 FPs per case, a nearly 44.8% reduction. The results indicate that the proposed Siamese neural network method, combined with the aggregation strategy, provide a viable strategy for the automated detection of spinal metastasis in MRI images.

PET/MR Imaging in Musculoskeletal Disorders

There is emerging evidence suggesting that PET/MR imaging will have a role in many aspects of musculoskeletal imaging. The synergistic potential of hybrid PET/MR imaging in terms of acquiring anatomic, molecular, and functional data simultaneously seems advantageous in the diagnostic workup, treatment planning and monitoring, and follow-up of patients with musculoskeletal malignancies, and may also prove helpful in assessment of musculoskeletal infectious and inflammatory disorders. The application of more sophisticated MR imaging sequences and PET radiotracers other than FDG in the diagnostic workup and follow-up of patients with musculoskeletal disorders should be explored.

Detecting Tumor Metastases: The Road to Therapy Starts Here

Metastasis is the complex process by which primary tumor cells migrate and establish secondary tumors in an adjacent or distant location in the body. Early detection of metastatic disease and effective therapeutic options for targeting these detected metastases remain impediments to effectively treating patients with advanced cancers. If metastatic lesions are identified early, patients might maximally benefit from effective early therapeutic interventions. Further, monitoring patients whose primary tumors are effectively treated for potential metastatic disease onset is also highly valuable. Finally, patients with metastatic disease can be monitored for efficacy of specific therapeutic interventions through effective metastatic detection techniques. Thus, being able to detect and visualize metastatic lesions is key and provides potential to greatly improve overall patient outcomes. In order to achieve these objectives, researchers have endeavored to mechanistically define the steps involved in the metastatic process as well as ways to effectively detect metastatic progression. We presently overview various preclinical and clinical in vitro and in vivo assays developed to more efficiently detect tumor metastases, which provides the foundation for developing more effective therapies for this invariably fatal component of the cancerous process.