VIDEO: Preoperative CT Angiography for Scapula Osteocutaneous Free Flap Reconstructions.

OBJECTIVE. The objective of this video article is to discuss the use of the scapular osteocutaneous free flap in reconstructive procedures. We attempt to discuss normal and variant vascular anatomy, image acquisition via CT angiography, and image interpretation as well as computer-assisted design and manufacturing. CONCLUSION. The scapular osteocutaneous free flap is commonly used for maxillary and mandibular reconstructive surgery. The complex vasculature supplying the scapular region allows flap versatility. There are anatomic variations in the origin of the circumflex scapular and angular arteries. Our method of performing and reporting CT angiography for patients scheduled to undergo scapular osteocutaneous free flap procedures provides a reliable and reproducible means of communicating important elements of vasculature to surgeons. This in turn can facilitate the manufacturing of custom scapular cutting guides and improve surgical outcomes.

VIDEO: Preoperative CT Angiography for Fibular Free Flap Reconstructions.

OBJECTIVE: The objective of this video article is to provide an introduction to the use of fibular free flaps. Normal and variant vascular anatomy of the fibular free flap is discussed, as are imaging acquisition and CT angiography interpretation, computer-assisted design and manufacturing, and the limitations of the fibular free flap. CONCLUSION: The fibular free flap is commonly used for head and neck reconstructive surgery. Variation exists between individuals regarding the origin of the peroneal artery and the perforating arteries. Our method of performing CT angiography and reporting its findings for patients undergoing a fibular free flap procedure provides a reproducible means of identifying important elements of the vasculature and effectively communicating their locations to surgeons. Accurate communication can maximize the success of the flap harvesting and the preoperative manufacture of custom fibular cutting guides.

VIDEO: Preoperative CT Angiography for Anterolateral Thigh Flap Reconstructions.

OBJECTIVE: This video article will review the relevant vascular anatomy of the anterolateral thigh flap, describe the CT angiography (CTA) image acquisition, and describe how to report the locations of the perforating arteries along with characteristics that may be important to the surgeon. CONCLUSION: Our method of performing and reporting CTA for patients scheduled to undergo anterolateral thigh flap reconstruction provides a reproducible method of identifying perforating vessels and communicating their location to surgeons.

FDG PET/CT of primary bone tumors.

OBJECTIVE: Numerous primary bone tumors are encountered on (18)F-FDG PET/CT, and many are FDG avid. The degree of FDG uptake in bone tumors does not necessarily reflect malignant potential. In conjunction with radiographs, evaluation of morphologic characteristics on the CT portion of PET/CT scans is important for characterization of the lesions. FDG PET/CT has been found to be useful for staging and has also been found to reflect prognosis in some primary bone malignancies. The purpose of this article is to familiarize the reader with topics regarding FDG PET/CT and both malignant and benign primary bone tumors. CONCLUSION: FDG uptake alone is not adequate for characterizing primary bone tumors, and morphologic evaluation is an important factor in the interpretation of PET/CT scans. After diagnosis, FDG avidity and morphologic features can play an important role in staging and determining response to therapy. On completion of this article, readers should have an improved ability to evaluate the FDG uptake and CT morphologic features of malignant and benign primary bone tumors. Readers should also have a better understanding of the potential role of FDG PET/CT in the management of patients with osteosarcoma and Ewing sarcoma.

Cancer Radiomic and Perfusion Imaging Automated Framework: Validation on Musculoskeletal Tumors.

PURPOSE: Limitations from commercial software applications prevent the implementation of a robust and cost-efficient high-throughput cancer imaging radiomic feature extraction and perfusion analysis workflow. This study aimed to develop and validate a cancer research computational solution using open-source software for vendor- and sequence-neutral high-throughput image processing and feature extraction. METHODS: The Cancer Radiomic and Perfusion Imaging (CARPI) automated framework is a Python-based software application that is vendor- and sequence-neutral. CARPI uses contour files generated using an application of the user's choice and performs automated radiomic feature extraction and perfusion analysis. This workflow solution was validated using two clinical data sets, one consisted of 40 pelvic chondrosarcomas and 42 sacral chordomas with a total of 82 patients, and a second data set consisted of 26 patients with undifferentiated pleomorphic sarcoma (UPS) imaged at multiple points during presurgical treatment. RESULTS: Three hundred sixteen volumetric contour files were processed using CARPI. The application automatically extracted 107 radiomic features from multiple magnetic resonance imaging sequences and seven semiquantitative perfusion parameters from time-intensity curves. Statistically significant differences (P < .00047) were found in 18 of 107 radiomic features in chordoma versus chondrosarcoma, including six first-order and 12 high-order features. In UPS postradiation, the apparent diffusion coefficient mean increased 41% in good responders (P = .0017), while firstorder_10Percentile (P = .0312) was statistically significant between good and partial/nonresponders. CONCLUSION: The CARPI processing of two clinical validation data sets confirmed the software application's ability to differentiate between different types of tumors and help predict patient response to treatment on the basis of radiomic features. Benchmark comparison with five similar open-source solutions demonstrated the advantages of CARPI in the automated perfusion feature extraction, relational database generation, and graphic report export features, although lacking a user-friendly graphical user interface and predictive model building.

Fast Dixon whole-body MRI for detecting distant cancer metastasis: a preliminary clinical study.

PURPOSE: To evaluate the feasibility of fast Dixon whole-body (WB) magnetic resonance imaging (MRI) for detecting bone and liver metastasis in clinical patients and to compare its performance with skeletal scintigraphy (SS) for detecting bone metastases using reference imaging with >1 year follow-up as the gold standard. MATERIALS AND METHODS: Twenty-nine patients with bone metastases prospectively underwent WB MRI and SS. WB MRI included coronal T2, axial T1 with and without intravenous gadolinium (including triphasic liver sequences), and axial diffusion-weighted imaging, plus spinal sagittal postcontrast T1-weighted images. The skeleton was divided into 16 segments. Reviewers blinded to other images identified up to five lesions per segment and rated them using a five-point confidence scale for metastatic disease. Sensitivities and specificities were compared using the McNemar test. RESULTS: The sensitivity of WB MRI and SS in detecting bone metastases was 70.8% and 59.6% (P = 0.003), respectively; specificity was 89.1% and 98.7% (P < 0.0001). WB MRI detected all livers with metastases (n = 8). One focal nodular hyperplasia was classified as a metastasis on WB MRI. CONCLUSION: Fast Dixon WB MRI is feasible in clinical patients, highly specific, and more sensitive than SS in detecting bone metastases, and can detect metastases of the liver.

Radiography of pacemakers and implantable cardioverter defibrillators.

OBJECTIVE: The purpose of this article is to review the normal and abnormal radiographic appearances of cardiac pacemaker and implantable cardioverter defibrillator systems. CONCLUSION: Chest radiographs showing pacemakers and implantable cardioverter defibrillators contain identifying and clinically relevant information, such as MRI compatibility and possible malfunction. Accurate and timely reporting of these features provides important information that can improve patient care.

Skeletal muscle metastases: a three-part study of a not-so-rare entity.

OBJECTIVE: Our purposes were to explore the epidemiology of metastases to skeletal muscle and their detection on fused positron emission tomography and computed tomography. MATERIALS AND METHODS: We evaluated the epidemiology of skeletal muscle metastases in the literature and among cases from our hospital and studied the prevalence and appearance of skeletal muscle metastases among 433 patients undergoing fused positron emission tomography and computed tomography for non-small-cell lung cancer. RESULTS: We found 264 cases of skeletal muscle metastases in 151 articles. Mean age was 57.8 years with 67% men. At our hospital we studied 70 cases. Mean patient age was 55.7 years with 63% men. The most common source was lung cancer, and the most common site of involvement was the muscles of the trunk. Among our lung cancer patients undergoing fused positron emission tomography and computed tomography, we found 7 (1.6%) with skeletal muscle metastases. In only one of these seven patients was the metastasis first discovered by another imaging modality. In one patient discovery of the metastasis at fused positron emission tomography and computed tomography changed management. CONCLUSION: Skeletal muscle metastases are not rare. They may be more apparent at fused positron emission tomography and computed tomography than at other staging examinations, particularly contrast-enhanced CT scanning. Radiologists need to be alert to their presence when interpreting staging examinations in cancer patients.

Initial staging impact of fluorodeoxyglucose positron emission tomography/computed tomography in locally advanced breast cancer.

PURPOSE: Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) may reveal distant metastases more accurately than conventional imaging (CT, skeletal scintigraphy, chest radiography). We hypothesized that patients diagnosed with stage III noninflammatory breast cancer (non-IBC) and IBC by conventional imaging with PET/CT have a better prognosis than patients diagnosed without PET/CT. PATIENTS AND METHODS: We retrospectively identified 935 patients with stage III breast cancer in 2000-2009. We compared the relapse-free survival (RFS) and overall survival (OS) times of patients diagnosed by conventional imaging with those of patients diagnosed by conventional imaging plus PET/CT. Univariate and multivariate Cox proportional hazards regression models were used to assess associations between survival and PET/CT. RESULTS: RFS and OS times were not significantly different between patients imaged with PET/CT and those imaged without PET/CT. However, the RFS time in IBC patients was significantly different between patients imaged with PET/CT and those imaged without PET/CT on both univariate (hazard ratio [HR], 0.43; p = .014) and multivariate (HR, 0.33; p = .004) analysis. There was a trend for a longer OS duration in IBC patients imaged with PET/CT. CONCLUSION: Among IBC patients, adding PET/CT to staging based on conventional imaging might detect patients with metastases that were not detected by conventional imaging. The use of conventional imaging with PET/CT for staging in non-IBC patients is not justified on the basis of these retrospective data. The use of conventional imaging plus PET/CT in staging IBC needs to be studied prospectively to determine whether it will improve prognosis.

FDG-PET/CT compared with conventional imaging in the detection of distant metastases of primary breast cancer.

PURPOSE: Evidence from studies with small numbers of patients indicates that (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) accurately detects distant metastases in the staging of primary breast cancer. We compared the sensitivity and specificity of PET/CT and conventional imaging (CT, ultrasonography, radiography, and skeletal scintigraphy) for the detection of distant metastases in patients with primary breast cancer. PATIENTS AND METHODS: We performed a retrospective review that identified 225 patients with primary breast cancer seen from January 2000 to September 2009 for whom PET/CT data were available for review. Imaging findings were compared with findings on biopsy, subsequent imaging, or clinical follow-up. Sensitivity and specificity in the detection of distant metastases were calculated for PET/CT and conventional imaging. Fisher's exact tests were used to test the differences in sensitivity and specificity between PET/CT and conventional imaging. RESULTS: The mean patient age at diagnosis was 53.4 years (range, 23-84 years). The sensitivity and specificity in the detection of distant metastases were 97.4% and 91.2%, respectively, for PET/CT and 85.9% and 67.3%, respectively, for conventional imaging. The sensitivity and specificity of PET/CT were significantly higher than those of conventional imaging (p = .009 and p < .001, respectively). Eleven cases of distant metastases detected by PET/CT were clinically occult and not evident on conventional imaging. CONCLUSION: PET/CT has higher sensitivity and specificity than conventional imaging in the detection of distant metastases of breast cancer. A prospective study is needed to determine whether PET/CT could replace conventional imaging to detect distant metastases in patients with primary breast cancer.

Comparison of gadolinium-enhanced fat-saturated T1-weighted FLAIR and fast spin-echo MRI of the spine at 3 T for evaluation of extradural lesions.

OBJECTIVE: Inversion recovery has been used to correct the loss of CSF and tissue contrast at 3 T versus 1.5 T but has not been formally investigated in the spine after IV administration of gadolinium-based contrast agent. The purpose of this study is to compare two sequences for gadolinium-enhanced spine imaging at 3 T--fat-saturated T1-weighted FLAIR and fat-saturated T1-weighted fast spin-echo (FSE)--for evaluation of extradural lesions and CSF-cord contrast. MATERIALS AND METHODS: After IV administration of gadolinium-based contrast agent, fat-saturated T1-weighted FSE and FLAIR sequences were obtained in 156 MRI scans of 143 patients at 3 T. Three experienced radiologists compared these sequences for conspicuity differences in bone lesions, disk lesions, other epidural lesions, and cord-CSF contrast. A 7-point visual rating scale was used, with lower numbers indicating increased conspicuity on gadolinium-enhanced fat-saturated T1-weighted FLAIR and higher numbers indicating increased conspicuity on gadolinium-enhanced fat-saturated T1-weighted FSE. RESULTS: A slight increase in the conspicuity of gadolinium-enhancing bone lesions (mean score, 3.6; p < 0.0001), disk lesions (mean score, 3.5; p < 0.0001), and epidural lesions (mean score, 3.4; p < 0.0001) was seen on fat-saturated T1-weighted FLAIR compared with fat-saturated T1-weighted FSE. A higher degree of contrast between the spinal cord and CSF was seen on fat-saturated T1-weighted FLAIR, by a large margin (mean score, 1.8; p < 0.0001). All enhancing lesions seen on fat-saturated T1-weighted FSE images were also seen on fat-saturated T1-weighted FLAIR images. CONCLUSION: Decreased CSF-cord contrast at 3 T, as seen on T1-weighted FSE, can be regained by using T1-weighted FLAIR. Fat-saturated T1-weighted FLAIR may increase conspicuity of gadolinium-enhancing extradural lesions compared with fat-saturated T1-weighted FSE.

Central venous line placement in the superior vena cava and the azygos vein: differentiation on posteroanterior chest radiographs.

OBJECTIVE: The purpose of this study was to determine, first, the accuracy with which radiologists reading posteroanterior chest radiographs differentiate whether a central venous line is in the superior vena cava or the azygos vein and, second, the circumstances in which radiologists may omit the lateral view to determine the position of a central venous line. MATERIALS AND METHODS: Twenty-four radiologists evaluated 60 posteroanterior chest radiographs to determine the position of a central venous line in the superior vena cava or azygos vein. Investigators evaluated the appearance of the central venous lines to refine rules for determining central venous line position on a frontal radiograph and omitting the lateral view. RESULTS: The accuracy of posteroanterior radiography for determining central venous line position was 90% at one study location and 85.5% at the other. No central venous line in the azygos vein extended more than 10.9 mm caudal to the cephalic edge of the right main bronchus. No central venous line in the superior vena cava had a down-the-barrel or curved appearance at the caudal edge. CONCLUSION: For central venous lines extending at least 15 mm caudal to the cephalic edge of the right main bronchus and having no down-the-barrel or curved caudal appearance, categorization was nearly 100% accurate. Therefore, if desired to save radiation exposure and cost, it may be feasible to omit lateral views in radiography of patients with central venous lines extending at least 15 mm caudal to the cephalic edge of the right main bronchus in whom the caudal edge does not have a down-the-barrel or curved appearance.

Comparison of half-dose and full-dose gadolinium MR contrast on the enhancement of bone and soft tissue tumors.

OBJECTIVE: To evaluate the effect of half-dose intravenous gadolinium contrast on the enhancement of bone and soft tissue tumors. MATERIALS AND METHODS: This study is HIPAA compliant and informed consent was waived by the institutional review board. An institutional database search was performed over a 1-year period for patients with full- and half-dose MR examinations performed for musculoskeletal oncologic indications. Examination pairs that were identical with regard to field strength and presence or absence of fat saturation were included, resulting in 29 paired examinations. When multiple, the lesion that was best delineated and enhanced well on the first examination in the pair was chosen, yielding 17 bone and 12 soft tissue. Five musculoskeletal radiologists blinded to dosages were asked to assess for a difference in enhancement when comparing the lesion on both examinations and to rate the degree of difference on a three-point scale. They were also asked to identify the examination on which the lesion enhanced less (tallied as low dose). Results were analyzed with the exact binomial test. RESULTS: The readers perceived an enhancement difference in 41% (59/145) of studies (p = 0.03) and the majority were rated as "mild" (66%, 39/59). The readers did not accurately identify the low-dose examinations (54% correctly identified, 32/59, p = 0.60). CONCLUSIONS: Half-dose gadolinium enhancement of lesions could not be accurately distinguished from full-dose enhancement upon review of the same lesion imaged at both concentrations.

An Approach to Undiagnosed Bone Tumors.

The radiographic appearance of primary bone tumors is important for initial diagnosis and often augments histopathological analysis. The original grading system relied on the radiographic analysis of the margin of the lesions to determine tumor aggression, which often corresponds with malignant potential. The recently developed, modified Lodwick-Madewell grading system also incorporates the appearance of lesion margins on radiographs but also considers the change in margins on serial radiographs and includes a category for clinically suspected, radiographically occult, aggressive lesions. This article reviews the prior and modified grading systems, and the concepts necessary for proper interpretation of the initial appearance of bone tumors which often determines the radiologist's recommendation for biopsy or follow-up imaging.

Advanced Imaging in Musculoskeletal Oncology: Moving Away From RECIST and Embracing Advanced Bone and Soft Tissue Tumor Imaging (ABASTI) - Part I - Tumor Response Criteria and Established Functional Imaging Techniques.

According to the Revised Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, the majority of bone metastases are considered to be nonmeasurable disease. Traditional response criteria rely on physical measurements. New criteria would be valuable if they incorporated newly developed imaging features in order to provide a more comprehensive assessment of oncological status. Advanced magnetic resonance imaging (MRI) sequences such as diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) with dynamic contrast-enhanced (DCE) perfusion imaging are reviewed in the context of the initial and post-therapeutic assessment of musculoskeletal tumors. Particular attention is directed to the pseudoprogression phenomenon in which a successfully treated tumor enlarges from the pretherapeutic baseline, followed by regression without a change in therapy.

Advanced Imaging in Musculoskeletal Oncology: Moving Away From RECIST and Embracing Advanced Bone and Soft Tissue Tumor Imaging (ABASTI)-Part II-Novel Functional Imaging Techniques.

Functional imaging can add valuable information to conventional imaging in the settings of tumor characterization and treatment response assessment. Traditional response criteria rely primarily on physical measurements, while functional imaging can potentially give a more comprehensive evaluation of oncological status. The second part of this review article discusses advanced imaging techniques such as susceptibility-weighted imaging, tumor-associated macrophage imaging, diffusion-weighted imaging, perfusion-weighted imaging, Dixon imaging, whole-body magnetic resonance imaging, whole-body low-dose dual energy computed tomography with virtual noncalcium technique, and ultrasound elastography.

Bone Metastases: Mechanisms of the Metastatic Process, Imaging and Therapy.

The mechanisms by which tumors metastasize to bone are complex. Upon the successful establishment of metastatic deposits in the skeleton, detection of the disease becomes essential for therapeutic planning. The roles of CT, skeletal scintigraphy, SPECT/CT, MRI, PET/CT and PET/MRI will be reviewed. Therapeutic response criteria specifically designed to evaluate bone metastases (MD Anderson/MDA criteria) can guide image interpretation. Knowledge of therapeutic strategies such as systemic therapy with bisphosphonates or radiopharmaceuticals, radiation therapy, surgery, and percutaneous interventions such as vertebroplasty and radiofrequency ablation can help the radiologist produce reports that will provide maximum benefit to clinicians and patients.

Tumor necrosis in osteosarcoma: inclusion of the point of greatest metabolic activity from F-18 FDG PET/CT in the histopathologic analysis.

OBJECTIVE: To determine if the location of the point of maximum standardized uptake value (SUVmax) being included in or not included in the histopathologic slab section corresponded to tumor necrosis or survival. MATERIALS AND METHODS: Twenty-nine osteosarcoma patients underwent post-chemotherapy [fluorine-18]-fluoro-2-deoxy-D: -glucose (FDG) positron-emission tomography-computed tomography (PET/CT) prior to resection. PET/CT images were correlated with slab-section location as determined by photographs or knowledge of specimen processing. The location of the point of SUVmax was then assigned as being 'in' or 'out' of the slab section. Cox's proportional hazard regression was used to evaluate relationships between the location and value of SUVmax and survival. Logistic regression was employed to evaluate tumor necrosis. RESULTS: No correlation was found between the SUVmax location and survival or tumor necrosis. High SUVmax correlated to poor survival. CONCLUSION: High SUVmax value correlated to poor survival. Minimal viable tumor (> 10%) following chemotherapy is a known indicator of poor survival. No correlation was found between the location of SUVmax and survival or tumor necrosis. Therefore, the SUVmax value either does not correspond to a sufficient number of tumor cells to influence tumor necrosis measurement or it was included in the out-of-slab samples that were directed to viable-appearing areas of the gross specimen. Since high SUVmax has been previously found to correspond to poor tumor necrosis, and tumor necrosis is simply an estimate of the amount of viable tumor, SUVmax likely represents many viable tumor cells. Therefore, when not in the slab section, SUVmax was likely included in the tumor necrosis measurement through directed sampling, validating our current method of osteosarcoma specimen analysis.

Imaging bone metastases in breast cancer: techniques and recommendations for diagnosis.

Bone is the most common site of distant metastases from breast carcinoma. The presence of bone metastases affects a patient's prognosis, quality of life, and the planning of their treatment. We discuss recent innovations in bone imaging and present algorithms, based on the strengths and weaknesses of each technique, to facilitate the most successful and cost-effective choice of imaging studies for the detection of osseous metastases. Skeletal scintigraphy (bone scan) is very sensitive in the detection of osseous metastases and is recommended as the first imaging study in patients who are asymptomatic. Radiographs are recommended for the assessment of abnormal radionuclide uptake or the risk of pathological fracture and as initial imaging studies in patients with bone pain. MRI or PET-CT can be considered for cases of abnormal radionuclide uptake that are not addressed by radiography. Osseous metastases can lead to emergent situations, such as spinal-cord compression or impending fracture of a weight-bearing bone, and imaging guidelines are essential for early detection and initiation of appropriate therapy. The imaging method used in non-emergent situations, such as assessment of the ribs, sternum, pelvis, hips, and joints, should be guided by the strengths and limitations of each technique.

Risks and Benefits of Gadolinium-Based Contrast-Enhanced MRI.

The responsible use of gadolinium-based contrast agents (GBCAs) requires a balance between safety and clinical utility. While nephrogenic systemic fibrosis (NSF) has been associated with most linear GBCAs few, if any, new cases have been verified since the successful implementation of screening programs to detect renal impairment and prevent susceptible patients from receiving these higher-risk agents. The likelihood of developing nephrogenic systemic fibrosis has been shown to be negligible with macrocyclic agents, prompting the American College of Radiology and other regulatory agencies to suggest that no screening is necessary when they are used. There is no solid evidence of negative clinical effect from the retention of macrocyclic agents in the brain while there is evidence that they wash out of the brain over time. GBCAs have many important clinical uses that can help prevent morbidity or death. This article reviews the risks and benefits of GBCA administration.