Christopher J. Hanrahan

Current Concepts in the Evaluation of Multiple Myeloma with MR Imaging and FDG PET/CT

Multiple myeloma is a heterogeneous group of plasma cell neoplasms that primarily involve bone marrow but also may occur in the soft tissue. Although the disease varies in its manifestations and its course, it is eventually fatal in all cases. Over the past 2 decades, significant advances have been made in our understanding of the genetics and pathogenesis of multiple myeloma and in its treatment. The use of magnetic resonance (MR) imaging and fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) has improved sensitivity for the detection of this disease. PET aids in the identification of active multiple myeloma on the basis of FDG uptake, and MR imaging helps identify multiple myeloma from its infiltration of normal fat within the bone marrow, which occurs in characteristic patterns that correlate with the disease stage. The increased sensitivity of these advanced cross-sectional imaging techniques has led to further refinement of the classic Durie and Salmon staging system. In addition, these imaging techniques allow a more reliable assessment of the disease response to treatment with current regimens, which may include autologous stem cell transplantation as well as various medications. In lesions that respond to chemotherapeutic agents, the replacement of previously infiltrated marrow by fat is seen at MR imaging and decreased FDG uptake is seen at FDG PET; however, a lengthy and intensive regimen may be necessary before the MR imaging appearance of marrow normalizes. Lytic lesions seen at CT almost always persist even after successful treatment. To provide an accurate assessment, radiologists must be familiar not only with the appearances of multiple myeloma and its mimics but also with common treatment-related findings.

MRI of Spinal Bone Marrow: Part 2, T1-Weighted Imaging-Based Differential Diagnosis

OBJECTIVE The purpose of this article is to review the structure of bone marrow and the differential diagnosis of bone marrow pathology on the basis of T1-weighted MRI patterns. CONCLUSION Bone marrow is an organ that is evaluated routinely during MRI of the spine, particularly lumbar spine evaluation. Thus, it is one of the most commonly performed MRI examinations. T1-weighted MRI is a fundamental sequence in evaluating spinal marrow, and an understanding of T1-weighted MR signal abnormalities is important for the practicing radiologist.

MRI of Spinal Bone Marrow: Part 1, Techniques and Normal Age-Related Appearances

OBJECTIVE This article reviews MRI protocols, including routine and nonroutine pulse sequences as well as the normal MRI appearance of spinal marrow and expected age-related changes. CONCLUSION Routine MRI of the spine provides useful evaluation of the spinal bone marrow, but nonroutine MRI pulse sequences are increasingly being used to evaluate bone marrow pathology. An understanding of MRI pulse sequences and the normal and age-related appearances of bone marrow is important for the practicing radiologist.

18F-FDG PET in the Evaluation of Acuity of Deep Vein Thrombosis

Purpose 18F-FDG PET has been used for vascular disease, but its role in deep vein thrombosis (DVT) remains prospectively unexplored. Patients and Methods Whole-body 18F-FDG PET/CT scans were performed in patients 1 to 10 weeks after onset of symptomatic DVT (n = 12) and in control subjects without DVT (n = 24). The metabolic activity (SUVmax) of thrombosed and contralateral nonthrombosed vein segments was determined. The sensitivity and specificity of 18F-FDG PET/CT for the diagnosis of DVT were determined by receiver operating characteristic curve analyses. In 2 patients with DVT, changes in the metabolic activity of thrombosed vein segments in serial 18F-FDG PET scans. Results The metabolic activity in thrombosed veins [SUVmax, 2.41 (0.75)] was visually appreciable and significantly higher than in nonthrombosed veins in either the contralateral extremity of patients with DVT [SUVmax, 1.09 (0.25), P = 0.007] or control subjects [1.21 (0.22), P < 0.001]. The area under the receiver operating characteristic curve for SUVmax was 0.9773 (P < 0.001), indicating excellent accuracy. An SUVmax threshold of greater than 1.645 was 87.5% sensitive and 100% specific for DVT. Metabolic activity in thrombosed veins correlated significantly with time from DVT symptom onset (decrease in SUVmax of 0.02/d, P < 0.05). Best-fit-line analyses suggested that approximately 84 to 91 days after acute DVT, the maximum metabolic activity of thrombosed veins would return to normal levels. Conclusions 18F-FDG PET/CT is accurate for detecting acute symptomatic, proximal DVT. Metabolic activity in thrombosed veins decreases with time, suggesting that 18F-FDG PET may be helpful in assessing the age of the clot.

Temporal Evolution of MRI Findings After Arthroscopic Rotator Cuff Repair

OBJECTIVE The purpose of this article is to assess the changes occurring over time in the MRI appearance of repaired rotator cuff tendons and to correlate MRI appearance with clinical outcomes. SUBJECTS AND METHODS MRI examinations were performed on 40 patients with full-thickness rotator cuff tears preoperatively and at 6 weeks, 3 months, and 12 months after arthroscopic repair. Preoperative scans were assessed for size of tear. Postoperative scans were evaluated for size of footprint, tendon thickness, signal intensity of the repaired tendon, and presence of full-thickness tear. Footprint and tendon thickness were graded from 1 to 4 according to percentage of normal. Tendon signal intensity was graded from 1 to 4 on the basis of the length of abnormal tendon. A composite score of footprint, tendon thickness, and tendon signal intensity was used to compare overall tendon appearance relative to the intact tendon. Rasch analysis was used to transform ordinal scale data into interval scale data. Using interval scale data, MRI findings were correlated to shoulder strength and the Constant-Murley score of clinical outcome. RESULTS Four recurrent tendon tears occurred during the first postoperative year. Tendons appeared most disorganized compared with native tendon 3 months after surgery. Twenty-four of 36 intact tendons showed a decreased tendon score between 6 weeks and 3 months. There was considerable variability in tendon appearance among patients. There was no correlation between MRI appearance and clinical outcome score. CONCLUSION MRI appearance of the repaired tendon changes over time but does not correlate with function or predict clinical outcomes at 1 year after surgery.

Can imaging criteria distinguish enchondroma from grade 1 chondrosarcoma

PURPOSE To minimize systematic bias and optimize agreement on imaging criteria in order to better define the accuracy of imaging criteria in the diagnosis of grade 1 chondrosarcoma. MATERIALS AND METHODS Study was IRB-approved and HIPAA compliant; informed consent was waived. Records were reviewed and disclosed 53 cases (38 women, 15 men ages 21-76) which were diagnosed as enchondroma or grade 1 chondrosarcoma and had available radiographs, contrast-enhanced MRI, and definitive diagnosis by histology or 5-year follow-up. 2 MSK radiologists read the studies independently after a session where they agreed on criteria for malignancy. Interobserver variability was determined as raw variability and with the kappa statistic. Accuracy was determined compared to final diagnosis. Reliability of imaging features of chondrosarcoma was determined using regression analysis. RESULTS The correct diagnosis of enchondroma was made on radiographs in 43 (67.2%) of readings, and on MRI in 37/64 (57.8%). The correct diagnosis of chondrosarcoma was made on radiographs in 5/24 (20.8%) of readings, and on MRI in 14/24 (57.8%). A diagnosis of borderline lesion was made in 19/64 (29.7%) of enchondromas on radiographs and 18/64 (28.1%) on MRI. The false positive rate of radiographs for chondrosarcoma was 2/64 (3.1%) and the false positive rate of MRI was 9/64 (14.1%). There was substantial interobserver variability. Cortical thickening and bone expansion were rare but specific signs of chondrosarcoma. CONCLUSIONS Both radiographs and MRI have limitations in the evaluation of low-grade cartilage lesions. MRI has an increased rate of both true-positive and false-positive diagnosis compared to radiographs. Differences in the findings of this study compared to previous literature may reflect the influence of systematic biases.

Accuracy of 3D dual echo steady state (DESS) MR arthrography to quantify acetabular cartilage thickness

To deploy and quantify the accuracy of 3D dual echo steady state (DESS) MR arthrography with hip traction to image acetabular cartilage. Clinical magnetic resonance imaging (MRI) sequences used to image hip cartilage often have reduced out‐of‐plane resolution and may lack adequate signal‐to‐noise to image cartilage.

Imaging of Multiple Myeloma: Usefulness of MRI and PET/CT

Multiple myeloma is a heterogeneous hematologic disorder of plasma cells with varied bone marrow imaging appearances. With advancements in both treatment and use of advanced imaging over the last several decades, it is important for radiologists to recognize the imaging presentation of the disease and the staging implications of imaging. This paper reviews the staging as it relates to imaging, consensus recommendations for imaging, expected imaging appearances of myeloma, pitfalls, and complications associated with treatment that are demonstrable on imaging.

Weightbearing computed tomography of the foot and ankle : emerging technology topical review

In the last decade, cone-beam computed tomography technology with improved designs allowing flexible gantry movements has allowed both supine and standing weight-bearing imaging of the lower extremity. There is an increasing amount of literature describing the use of weightbearing computed tomography in patients with foot and ankle disorders. To date, there is no review article summarizing this imaging modality in the foot and ankle. Therefore, we performed a systematic literature review of relevant clinical studies targeting the use of weightbearing computed tomography in diagnosis of patients with foot and ankle disorders. Furthermore, this review aims to offer insight to those with interest in considering possible future research opportunities with use of this technology. Level of Evidence: Level V, expert opinion.

18F-fluoro-2-deoxyglucose PET informs neutrophil accumulation and activation in lipopolysaccharide-induced acute lung injury

INTRODUCTION Molecular imaging of the earliest events related to the development of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) could facilitate therapeutic development and patient management. We previously reported that 18F-fluoro-2-deoxyglucose (18F-FDG) PET identifies ALI/ARDS prior to radiographic abnormalities. The purpose of this study was to establish the time courses of 18F-FDG uptake, edema and neutrophil recruitment in an endotoxin-induced acute lung injury model and to examine molecular events required for 14C-2DG uptake in activated neutrophils. METHODS Lung uptake of 18F-FDG was measured by PET in control male Sprague Dawley rats and at 2, 6 and 24h following the intraperitoneal injection of 10mg/kg LPS. Lung edema (attenuation) was measured by microCT. Neutrophil influx into the lungs was measured by myeloperoxidase assay. Control and activated human donor neutrophils were compared for uptake of 14C-2DG, transcription and content of hexokinase and GLUT isoforms and for hexokinase (HK) activity. RESULTS Significant uptake of 18F-FDG occurred by 2h following LPS, and progressively increased to 24h. Lung uptake of 18F-FDG preceded increased CT attenuation (lung edema). Myeloperoxidase activity in the lungs, supporting neutrophil influx, paralleled 18F-FDG uptake. Activation of isolated human neutrophils resulted in increased uptake of 14C-2DG, expression of GLUT 3 and GLUT 4 and expression and increased HK1 activity. CONCLUSION Systemic endotoxin-induced ALI results in very early and progressive uptake of 18F-FDG, parallels neutrophil accumulation and occurs earlier than lung injury edema. Activated neutrophils show increased uptake of 14C-2DG, expression of specific GLUT3, GLUT4 and HK1 protein and HK activity. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: 18F-FDG pulmonary uptake is an early biomarker of neutrophil recruitment in ALI and is associated with specific molecular events that mediate 14C-2DG uptake in activated neutrophils. 18F-FDG PET may provide a potential mechanism for early diagnosis and therapeutic assessment of ALI/ARDS.