Age-Related Changes in the Metabolic Activity and Distribution of the Red Marrow as Demonstrated by 2-Deoxy-2-[F-18]fluoro-d-glucose-Positron Emission Tomography

A comprehensive review of the role of bone marrow biopsy and PET-CT in the evaluation of bone marrow involvement in adults newly diagnosed with DLBCL

Diffuse large B cell lymphoma (DLBCL) is one of the most prevalent subtypes of non-Hodgkin lymphoma (NHL) and is known for commonly infiltrating extra-nodal sites. The involvement of the bone marrow by lymphoma cells significantly impacts the staging, treatment, and prognosis among the extra-nodal sites in DLBCL. Bone marrow biopsy has been considered the standard diagnostic procedure for detecting bone marrow involvement. However, advancements in imaging techniques, such as positron emission tomography-computed tomography (PET-CT), have shown an improved ability to detect bone marrow involvement, making the need for bone marrow biopsy debatable. This review aims to emphasize the importance of bone marrow evaluation in adult patients newly diagnosed with DLBCL and suggest an optimal diagnostic approach to identify bone marrow involvement in these patients.

[18F]FDG PET/MRI in children suffering from lymphoma: does MRI contrast media make a difference?

OBJECTIVES

Evaluate the influence of an MRI contrast agent application on primary and follow-up staging in pediatric patients with newly diagnosed lymphoma using [18F]FDG PET/MRI to avoid adverse effects and save time and costs during examination.

METHODS

A total of 105 [18F]FDG PET/MRI datasets were included for data evaluation. Two different reading protocols were analyzed by two experienced readers in consensus, including for PET/MRI-1 reading protocol unenhanced T2w and/or T1w imaging, diffusion-weighted imaging (DWI), and [18F]FDG PET imaging and for PET/MRI-2 reading protocol an additional T1w post contrast imaging. Patient-based and region-based evaluation according to the revised International Pediatric Non-Hodgkin's Lymphoma (NHL) Staging System (IPNHLSS) was performed, and a modified standard of reference was applied comprising histopathology and previous and follow-up cross-sectional imaging. Differences in staging accuracy were assessed using the Wilcoxon and McNemar tests.

RESULTS

In patient-based analysis, PET/MRI-1 and PET/MRI-2 both determined a correct IPNHLSS tumor stage in 90/105 (86%) exams. Region-based analysis correctly identified 119/127 (94%) lymphoma-affected regions. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for PET/MRI-1 and PET/MRI-2 were 94%, 97%, 90%, 99%, 97%, respectively. There were no significant differences between PET/MRI-1 and PET/MRI-2.

CONCLUSIONS

The use of MRI contrast agents in [18F]FDG PET/MRI examinations has no beneficial effect in primary and follow-up staging of pediatric lymphoma patients. Therefore, switching to a contrast agent-free [18F]FDG PET/MRI protocol should be considered in all pediatric lymphoma patients.

CLINICAL RELEVANCE STATEMENT

This study gives a scientific baseline switching to a contrast agent-free [18F]FDG PET/MRI staging in pediatric lymphoma patients. This could avoid side effects of contrast agents and saves time and costs by a faster staging protocol for pediatric patients.

KEY POINTS

• No additional diagnostic benefit of MRI contrast agents at [18F]FDG PET/MRI examinations of pediatric lymphoma primary and follow-up staging • Highly accurate primary and follow-up staging of pediatric lymphoma patients at MRI contrast-free [18F]FDG PET/MRI.

Prognostic value of 18F-fluorodeoxyglucose uptake in the bone marrow on pretreatment positron emission tomography/computed tomography in patients with esophageal cancer who underwent esophagectomy

BACKGROUND

Increased 18F-fluorodeoxyglucose (FDG) uptake in the bone marrow (BM) on positron emission tomography/computed tomography (PET/CT) clinically reflects increased BM metabolism owing to systemic inflammation, bacterial infection, anemia, and cytokine-producing tumors. The association between FDG uptake in the BM and prognosis after esophagectomy for esophageal cancer has not been investigated.

METHODS

This study included 651 patients who underwent PET/CT before any treatment and McKeown esophagectomy for esophageal cancer between June 2007 and August 2021. The pretreatment degree of FDG uptake in the BM was evaluated using a visual assessment criterion. Patients were divided into low- and high-FDG uptake groups. We retrospectively investigated whether the degree of FDG uptake in the BM was associated with clinicopathological and surgical backgrounds, blood parameters, and prognosis.

RESULTS

High FDG uptake in the BM was significantly associated with elevated white blood cell and neutrophil counts, increased C-reactive protein levels, decreased hemoglobin, serum albumin, and total cholesterol levels. High FDG uptake in the BM was an independent predictor of worse overall survival in clinical stages 0-II esophageal cancer (hazard ratio, 2.27; 95% confidence interval, 1.097-4.695; P = 0.027). Worse overall survival was also associated with advanced age, low American Society of Anesthesiologists physical status, an advanced clinical stage, and high intraoperative blood loss.

CONCLUSION

Increased FDG uptake in the BM on pretreatment PET/CT may be a surrogate indicator of various clinically disadvantageous backgrounds and may act as a predictor of poor prognosis after esophageal cancer surgery.

Advances in Bone Marrow Imaging: Strengths and Limitations from a Clinical Perspective

Conventional magnetic resonance imaging (MRI) remains the modality of choice to image bone marrow. However, the last few decades have witnessed the emergence and development of novel MRI techniques, such as chemical shift imaging, diffusion-weighted imaging, dynamic contrast-enhanced MRI, and whole-body MRI, as well as spectral computed tomography and nuclear medicine techniques. We summarize the technical bases behind these methods, in relation to the common physiologic and pathologic processes involving the bone marrow. We present the strengths and limitations of these imaging methods and consider their added value compared with conventional imaging in assessing non-neoplastic disorders like septic, rheumatologic, traumatic, and metabolic conditions. The potential usefulness of these methods to differentiate between benign and malignant bone marrow lesions is discussed. Finally, we consider the limitations hampering a more widespread use of these techniques in clinical practice.

Comparing the diagnostic value of 18F-FDG PET/CT scan and bone marrow biopsy in newly diagnosed pediatric neuroblastoma and ganglioneuroblastoma

Objective

This study aims to compare the diagnostic value of ¹⁸F-fluorodeoxyglucose (18-FDG) positron emission tomography (PET)/computed tomography (CT) (¹⁸F-FDG PET/CT) scan and bone marrow biopsy (BMB) for evaluating bone marrow infiltration (BMI) in newly diagnosed pediatric neuroblastoma (NB) and ganglioneuroblastoma (GNB).

Methods

We retrospectively reviewed 51 patients with newly diagnosed NB and GNB between June 1, 2019 and May 31, 2022. Each patient had undergone ¹⁸F-FDG PET/CT and BMB within 1 week and received no treatment. Clinical data were collected and statistically analyzed, including age, sex, pathologic type, and laboratory parameters. ¹⁸F-FDG PET/CT and BMB revealed the result of bone lesions.

Results

A concordance analysis showed that, in this study population, ¹⁸F-FDG PET/CT and BMB were in moderate agreement (Cohen's Kappa = 0.444; p = 0.001), with an absolute agreement consistency of 72.5% (37 of 51). The analysis of the receiver operating characteristic (ROC) curve determined that the areas under the ROC curve (AUCs) of SUV_BM and SUV/HE-SUVmax were 0.971 (95% CI: 0.911-1.000; p < 0.001) and 0.917 (95% CI: 0.715-1.000; p < 0.001) to predict bone-bone marrow involvement (BMI), respectively.

Conclusion

¹⁸F-FDG PET/CT detects BMI with good diagnostic accuracy and can reduce unnecessary invasive inspections in newly diagnosed pediatric NB and GNB, especially patterns C and D. The analysis of the semi-quantitative uptake of ¹⁸F-FDG, including SUV_BM and SUV_BM/HE-SUVmax, enables an effective differentiation between patterns A and B.

Semi-automated histogram analysis of normal bone marrow using 18F-FDG PET/CT: correlation with clinical indicators

Background

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly applied to the diagnosis of bone marrow failure such as myeloproliferative neoplasm, aplastic anemia, and myelodysplastic syndrome, as well as malignant lymphoma and multiple myeloma. However, few studies have shown a normal FDG uptake pattern. This study aimed to establish a standard of bone marrow FDG uptake by a reproducible quantitative method with fewer steps using deep learning-based organ segmentation.

Methods

Bone marrow PET images were obtained using segmented whole-spine and pelvic bone marrow cavity CT as mask images using a commercially available imaging workstation that implemented an automatic organ segmentation algorithm based on deep learning. The correlation between clinical indicators and quantitative PET parameters, including histogram features, was evaluated.

Results

A total of 98 healthy adults were analyzed. The volume of bone marrow PET extracted in men was significantly higher than that in women (p < 0.0001). Univariate and multivariate regression analyses showed that mean of standardized uptake value corrected by lean body mass (SUL_mean) and entropy in both men and women were inversely correlated with age (all p < 0.0001), and SUL_max in women were also inversely correlated with age (p = 0.011).

Conclusion

A normal FDG uptake pattern was demonstrated by simplified FDG PET/CT bone marrow quantification.

FDG PET/CT versus Bone Marrow Biopsy for Diagnosis of Bone Marrow Involvement in Non-Hodgkin Lymphoma: A Systematic Review

The management of non-Hodgkin lymphoma (NHL) patients requires the identification of bone marrow involvement (BMI) using a bone marrow biopsy (BMB), as recommended by international guidelines. Multiple studies have shown that [18F]FDG positron emission tomography, combined with computed tomography (PET/CT), may provide important information and may detect BMI, but there is still an ongoing debate as to whether it is sensitive enough for NHL patients in order to replace or be used as a complimentary method to BMB. The objective of this article is to systematically review published studies on the performance of [18F]FDG PET/CT in detecting BMI compared to the BMB for NHL patients. A population, intervention, comparison, and outcome (PICO) search in PubMed and Scopus databases (until 1 November 2021) was performed. A total of 41 studies, comprising 6147 NHL patients, were found to be eligible and were included in the analysis conducted in this systematic review. The sensitivity and specificity for identifying BMI in NHL patients were 73% and 90% for [18F]FDG PET/CT and 56% and 100% for BMB. For aggressive NHL, the sensitivity and specificity to assess the BMI for the [18F]FDG PET/CT was 77% and 94%, while for the BMB it was 58% and 100%. However, sensitivity and specificity to assess the BMI for indolent NHL for the [18F]FDG PET/CT was 59% and 85%, while for the BMB it was superior, and equal to 94% and 100%. With regard to NHL, a [18F]FDG PET/CT scan can only replace BMB if it is found to be positive and if patients can be categorized as having advanced staged NHL with high certainty. [18F]FDG PET/CT might recover tumors missed by BMB, and is recommended for use as a complimentary method, even in indolent histologic subtypes of NHL.

PET-Based Imaging with 18F-FDG and 18F-NaF to Assess Inflammation and Microcalcification in Atherosclerosis and Other Vascular and Thrombotic Disorders

Positron emission tomography (PET) imaging with ¹⁸F-fluorodeoxyglucose (FDG) represents a method of detecting and characterizing arterial wall inflammation, with potential applications in the early assessment of vascular disorders such as atherosclerosis. By portraying early-stage molecular changes, FDG-PET findings have previously been shown to correlate with atherosclerosis progression. In addition, recent studies have suggested that microcalcification revealed by ¹⁸F-sodium fluoride (NaF) may be more sensitive at detecting atherogenic changes compared to FDG-PET. In this review, we summarize the roles of FDG and NaF in the assessment of atherosclerosis and discuss the role of global assessment in quantification of the vascular disease burden. Furthermore, we will review the emerging applications of FDG-PET in various vascular disorders, including pulmonary embolism, as well as inflammatory and infectious vascular diseases.

Artificial Intelligence in Vascular-PET:: Translational and Clinical Applications

Positron emission tomography (PET) offers an incredible wealth of diverse research applications in vascular disease, providing a depth of molecular, functional, structural, and spatial information. Despite this, vascular PET imaging has not yet assumed the same clinical use as vascular ultrasound, CT, and MR imaging which provides information about late-onset, structural tissue changes. The current clinical utility of PET relies heavily on visual inspection and suboptimal parameters such as SUVmax; emerging applications have begun to harness the tool of whole-body PET to better understand the disease. Even still, without automation, this is a time-consuming and variable process. This review summarizes PET applications in vascular disorders, highlights emerging AI methods, and discusses the unlocked potential of AI in the clinical space.

Advanced Quantitative Spine Imaging

Although advanced quantitative imaging may not be currently used to any degree in the routine reporting of spinal examinations, this situation will change in the not too distant future. Advanced quantitative imaging has already allowed us to understand a great deal more regarding spinal development, marrow physiology, and disease pathogenesis. Radiologists are ideally suited to drive this research forward. To speed up this process and optimize the impact of studies reporting spine quantitative data, we should work toward universal standards on the acquisition of spine data that will allow quantitative studies to be more easily compared, contrasted, and amalgamated.

Integrated [18F]FDG PET/MRI demonstrates the iron-related bone-marrow physiology

We identified predictors for bone-marrow [¹⁸F]FDG uptake and MR signals among complete blood count, C-reactive protein (CRP), and anthropometric factors, and demonstrated the bone-marrow physiology using integrated [¹⁸F]FDG-PET/MRI. 174 oncology patients without bone-marrow lesions underwent whole-body [¹⁸F]FDG-PET/MRI. The standardized uptake value (SUV), apparent diffusion coefficient (ADC), proton density fat-fraction (PDFF), and a reciprocal of T2* relaxation time (R2*) were measured in lumbar vertebrae (L3-5) and bilateral ilia. Vertebrae, pelvis, and ribs were evaluated by 3-point visual scoring on DWI. The association of the PET/MR features with the predictors was examined. Multi-regression analyses identified CRP as the strongest predictor for lumbar and iliac SUVs (standardized coefficient: β = 0.31 and β = 0.38, respectively), and for lumbar and iliac R2* (β = 0.31 and β = 0.46, respectively). In contrast, age was the strongest factor influencing lumbar and iliac ADCs (β = 0.23 and β = 0.21, respectively), and lumbar and iliac PDFFs (β = 0.53 and β = 0.54, respectively). Regarding DWI-visual scores, age was the strongest predictor for vertebrae (β = - 0.47), and the red cell distribution width (RDW) was the strongest predictor for pelvis and ribs (β = 0.33 and β = 0.47, respectively). The bone-marrow [¹⁸F]FDG uptake and R2* reflect anemia of inflammation (increased granulopoiesis and reduced iron metabolism), whereas bone-marrow DWI and PDFF reflect age and anemia-responsive erythropoiesis.

An enlarged left adrenal gland is an indirect sign of infection on 18F-FDG PET/CT

OBJECTIVES

To determine whether hypermetabolisms of the spleen and bone marrow and an enlarged adrenal gland are significant indirect signs of infection on fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT performed in patients with known or suspected infectious disease.

PATIENTS AND METHODS

Potential indirect signs of infection were as follows: (i) investigated in a retrospectively selected group of patients referred to F-FDG PET/CT for a known or suspected infectious disease and among whom the presence or absence of infectious foci was ascertained in 43 and 12 cases, respectively, and (ii) further validated in groups prospectively constituted of 12 patients with severe sepsis and of 39 control patients with no sign of any infectious disease. Standardised uptake values were determined on left adrenal gland, spleen and bone marrow, whereas the size of left adrenal gland was assessed by its maximal surface on unenhanced axial computed tomography (CT) slices.

RESULTS

Only the maximal surface of the left adrenal gland was a predictor in the initial study group (infection: 2.72±0.99 cm vs. no infection: 1.85±0.76 cm, P=0.004) and further validation groups (sepsis: 2.79±0.83 cm vs. controls: 1.91±0.67 cm, P=0.001). Patients with a greater than 1.8 cm maximal surface had more than two-fold higher infection rate than the other patients in the initial study group [88 (36/41) vs. 36% (4/11), P=0.001], even when only considering the subgroup with no evident infectious focus on F-FDG PET/CT [76 (16/21) vs. 30% (3/10), P=0.02].

CONCLUSION

An enlarged left adrenal gland is a significant sign of infection on F-FDG PET/CT, even in the absence of any evident infectious focus on F-FDG PET/CT images.

Diagnostic and Clinical Impact of Staging 18F-FDG PET/CT in Mantle-Cell Lymphoma: A Two-Center Experience

INTRODUCTION

The diagnostic accuracy of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in staging mantle-cell lymphoma has not yet investigated. The aim of this 2-center retrospective study was to investigate the utility of ¹⁸F-FDG PET/CT in assessing nodal, splenic, bone marrow (BM), and gastrointestinal (GI) disease compared to CT, BM, and GI endoscopy; and to assess its clinical impact.

PATIENTS AND METHODS

One hundred twenty-two patients with histologically proven mantle-cell lymphoma were included. PET/CT BM findings were considered positive if isolated/multiple focal uptake in the BM not explained by benign findings and/or diffuse BM uptake higher than liver with/without focal uptakes were present. PET/CT findings were considered positive for GI involvement in the presence of isolated/multiple focal uptake in the GI organ.

RESULTS

All patients had positive PET/CT showing the presence of at least one hypermetabolic lesion, with the exception of one case. PET/CT results, compared to CT, detected more nodal and/or splenic lesions in 26 patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of PET/CT for BM were 52%, 98%, 97%, 65%, and 74%; for GI 64%, 91%, 69%, 90%, and 85%; and for GI excluding diabetic patients, 78%, 92%, 72%, 94%, and 89%. PET/CT permitted upstaging of 21 cases and downstaging of 2.

CONCLUSION

¹⁸F-FDG PET/CT showed excellent detection rate in nodal and splenic disease-a rate better than CT. For BM and GI evaluation, in order to reach good accuracy, the selection of patients and the use of specific criteria for evaluation of these organs seems to be crucial. Moreover, PET/CT altered the management and therapeutic approach in about 20% of patients.

Physiological uptake of 18F-FDG in the vertebral bone marrow in healthy adults on PET/CT imaging

BACKGROUND

18F-fluorodeoxyglucose *Equal contributors. positron emission tomography/computed tomography (18F-FDG PET/CT) has proven to be a valuable imaging modality for the assessment of bone marrow condition.

PURPOSE

To investigate the physiological uptake of 18F-FDG in the vertebral bone marrow in healthy adults on PET/CT imaging, and correlate the appearance with clinical factors including gender, body mass index, and age.

MATERIAL AND METHODS

A total of 64 healthy individuals underwent PET/CT scan, and for each vertebral body, the mean and maximum standardized uptake value (SUVmean and SUVmax) were determined in the central slice of vertebral body on the transversal fused PET/CT image. For each individual, the FDG uptake of the four regions was obtained by averaging the SUVmean and SUVmax of the vertebrae in individual regions.

RESULTS

The FDG uptake from thoracic to sacral vertebrae showed an upward trend first, then a downward trend, while that of cervical vertebrae was relatively stable. The SUVmax and SUVmean values of bone marrow in the old group (age ≥ 50 years) were significantly lower than those in the young group (age < 50 years) in all regions of the spine ( P < 0.05). FDG uptake of the whole spine showed significant negative correlation with age, and the strongest correlation was observed in lumbar spine (SUVmean: r = -0.364, P < 0.05; SUVmax: r = -0.344, P < 0.05).

CONCLUSION

FDG uptake showed a tendency to increase first then decrease from thoracic to sacral vertebrae while the tendency was not obvious in cervical vertebrae. In addition, the glycolytic metabolism of all the four regions decreased with advancing age.

Positron Emission Tomography-based Analysis Can Accurately Predict Bone Marrow Involvement With Mantle Cell Lymphoma

INTRODUCTION

Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin lymphoma and requires both bone marrow biopsy and fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to correctly stage the disease at diagnosis. However, accurate identification of bone marrow involvement by lymphoma on FDG PET/CT scans has not been previously demonstrated. We hypothesized that a voxel-based analysis of the iliac bones on the FDG PET/CT scan might provide insight into bone marrow involvement.

PATIENTS AND METHODS

A retrospective cohort study of patients with a diagnosis of MCL who had undergone both single iliac bone marrow biopsy and FDG-PET/CT scan from 1 study site were included in the development phase (n = 10). An additional 12 patients from a second institution were included in the validation phase. Using a semiautomated workflow, a voxel-based data set of FDG uptake within the bilateral iliac bones was captured for each patient. In the development phase, empirical receiver operating characteristic curves for each data set were fit. We then identified the standardized uptake value (SUV) threshold cutpoints at which the sensitivity and specificity were optimized to 100%. In the validation phase, we evaluated the performance of these candidate SUV threshold cutpoints in 15 additional patients from a second institution.

RESULTS

We found that 1 cutpoint, > 38% of voxels with activity < 0.95, outperformed all the other candidate cutpoints, correctly classifying all patients except for 1 (overall sensitivity, 100%; specificity, 87.5%).

CONCLUSION

The ability to correctly identify bone marrow involvement using FDG PET/CT-based voxel analysis provides promise as a novel noninvasive method of accurate staging.

Italian Multicenter Study on Accuracy of 18F-FDG PET/CT in Assessing Bone Marrow Involvement in Pediatric Hodgkin Lymphoma

INTRODUCTION

The present study investigated the utility of fluorine-18 (¹⁸F) fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing bone marrow involvement (BMI) compared with bone marrow biopsy (BMB) in newly diagnosed pediatric Hodgkin lymphoma (HL).

PATIENTS AND METHODS

A total of 224 pediatric patients with HL underwent ¹⁸F-FDG PET/CT at staging. BMB or follow-up imaging was used as the standard of reference for the evaluation of BMI.

RESULTS

¹⁸F-FDG PET/CT was negative for BMI in 193 cases. Of the 193 patients, the findings for 16 were originally reported as doubtful and later interpreted as negative for BMI, with negative findings on follow-up imaging and BMB. At BMB, 1 of the 16 patients (6.25%) had BMI. Of the 193 patients, 192 (99.48%) had negative BMB findings. Thus, the ¹⁸F-FDG PET/CT findings were truly negative for 192 patients and falsely negative for 1 patient for BMI.

CONCLUSION

¹⁸F-FDG PET/CT showed high diagnostic performance in the evaluation of BMI in pediatric HL. Thus, BMB should be ideally reserved for patients presenting with doubtful ¹⁸F-FDG PET/CT findings for BMI.

Benign Bone Conditions That May Be FDG-avid and Mimic Malignancy

Positron emission tomography with the radiotracer ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) plays an important role in the evaluation of bone pathology. However, FDG is not a cancer-specific agent, and knowledge of the differential diagnosis of benign FDG-avid bone alterations that may resemble malignancy is important for correct patient management, including the avoidance of unnecessary additional invasive tests such as bone biopsy. This review summarizes and illustrates the spectrum of benign bone conditions that may be FDG-avid and mimic malignancy, including osteomyelitis, bone lesions due to benign systemic diseases (Brown tumor, Erdheim-Chester disease, Gaucher disease, gout and other types of arthritis, Langerhans cell histiocytosis, and sarcoidosis), benign primary bone lesions (bone cysts, chondroblastoma, chondromyxoid fibroma, desmoplastic fibroma, enchondroma, giant cell tumor and granuloma, hemangioma, nonossifying fibroma, and osteoid osteoma and osteoblastoma), and a group of miscellaneous benign bone conditions (post bone marrow biopsy or harvest status, bone marrow hyperplasia, fibrous dysplasia, fractures, osteonecrosis, Paget disease of bone, particle disease, and Schmorl nodes). Several ancillary clinical and imaging findings may be helpful in discriminating benign from malignant FDG-avid bone lesions. However, this distinction is sometimes difficult or even impossible, and tissue acquisition will be required to establish the final diagnosis.

Optimizing the interval between G-CSF therapy and F-18 FDG PET imaging in children and young adults receiving chemotherapy for sarcoma

BACKGROUND

Granulocyte colony-stimulating factors (G-CSF) speed recovery from chemotherapy-induced myelosuppression but the marrow stimulation they cause can interfere with interpretation of F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) exams.

OBJECTIVE

To assess the frequency of interfering G-CSF-induced bone marrow activity on FDG PET imaging in children and young adults with Ewing sarcoma and rhabdomyosarcoma and to define an interval between G-CSF administration and FDG PET imaging that limits marrow interference.

MATERIALS AND METHODS

Blinded, retrospective review of FDG PET exams performed in patients treated with long-acting G-CSF as part of their chemotherapeutic regimen. Exams were subjectively scored by two reviewers (R1 and R2) who assessed the level of marrow uptake of FDG and measured standardized uptake values in the marrow, liver, spleen and blood pool. FDG PET findings were correlated with time since G-CSF administration and with blood cell counts.

RESULTS

Thirty-eight FDG PET exams performed in 17 patients were reviewed with 47.4% (18/38) of exams having marrow uptake of FDG sufficient to interfere with image interpretation. Primary predictors of marrow uptake of FDG were patient age (P=0.0037) and time since G-CSF exposure (P=0.0028 for subjective marrow uptake of FDG, P=0.008 [R1] and P=0.004 [R2] for measured maximum standardized uptake value (SUVmax)). The median interval between G-CSF administration and PET imaging in cases with marrow activity considered normal or not likely to interfere was 19.5 days (range: 7-55 days).

CONCLUSION

In pediatric and young adult patients with Ewing sarcoma and rhabdomyosarcoma, an interval of 20 days between administration of the long-acting form of G-CSF and FDG PET imaging should limit interference by stimulated marrow.

Opportunities and limitations of bone marrow biopsy and bone marrow FDG-PET in lymphoma

Bone marrow involvement in lymphoma may have prognostic and therapeutic consequences. Bone marrow biopsy (BMB) is the established method for the evaluation of the bone marrow. (18)F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) plays an important role in lymphoma staging, but its value in the assessment of the bone marrow and whether it can replace BMB is still a topic of debate and investigation. The purpose of this scientific communication is to provide an evidence-based overview about the opportunities and limitations of BMB and FDG-PET in the evaluation of the bone marrow in patients with lymphoma. This article first reviews the basic properties, opportunities and limitations of BMB and bone marrow FDG-PET, and then focuses on the clinical utility of BMB and bone marrow FDG-PET in three major lymphoma subtypes including Hodgkin lymphoma, diffuse large B-cell lymphoma, and follicular lymphoma.

Estimating the whole bone-marrow asset in humans by a computational approach to integrated PET/CT imaging

PURPOSE

Despite their relevance in clinical medicine, the extension and activity of the bone marrow (BM) cannot be directly evaluated in vivo. We propose a new method to estimate these variables by combining structural and functional maps provided by CT and PET.

METHODS

BM extension and glucose uptake were estimated in 102 patients undergoing whole-body PET/CT because of a history of nonmetastatic melanoma. Image analysis assumed that the BM is surrounded by compact bone. An iterative optimization scheme was applied to each CT slice to identify the external border of the bone. To identify compact bone, the algorithm measured the average Hounsfield coefficient within a two-pixel ring located just inside the bone contour. All intraosseous pixels with an attenuation coefficient lower than this cut-off were flagged as 1, while the remaining pixels were set at 0. Binary masks created from all CT slices were thus applied to the PET data to determine the metabolic activity of the intraosseous volume (IBV).

RESULTS

Estimated whole-body IBV was 1,632 ± 587 cm(3) and was higher in men than in women (2,004 ± 498 cm(3) vs. 1,203 ± 354 cm(3), P < 0.001). Overall, it was strictly correlated with ideal body weight (r = 0.81, P = 0.001) but only loosely with measured body weight (r = 0.43, P = 0.01). The average FDG standardized uptake value (SUV) in the thoracic and lumbar vertebrae was 2.01 ± 0.36, Accordingly, intraosseous voxels with SUV ≥ 1.11 (mean spine SUV - 2.5 × SD) were considered as active "red" BM and those with SUV <1.11 as "yellow" BM. Estimated red BM volume was 541 ± 195 ml, with a higher prevalence in the axial than in the appendicular skeleton (87 ± 8 % vs. 10 ± 8 %, P < 0.001). Again, red BM volume was higher in men than in women (7.8 ± 2.2 vs. 6.7 ± 2.1 ml/kg body weight, P < 0.05), but in women it occupied a greater fraction of the IBV (32 ± 7 % vs. 36 ± 10 %, P < 0.05). Patient age modestly predicted red BM SUV, while it was robustly and inversely correlated with red BM volume.

CONCLUSION

Our computational analysis of PET/CT images provides a first estimation of the extension and metabolism of the BM in a population of adult patients without haematooncological disorders. This information might represent a new window to explore pathophysiology the BM and the response of BM diseases to chemotherapy.

State-of-the-art of bone marrow analysis in forensic toxicology: a review

Although blood is the reference medium in the field of forensic toxicology, alternative matrices are required in case of limited, unavailable or unusable blood samples. The present review investigated the suitability of bone marrow (BM) as an alternative matrix to characterize xenobiotic consumption and its influence on the occurrence of death. Basic data on BM physiology are reported in order to highlight the specificities of this matrix and their analytical and toxicokinetic consequences. A review of case reports, animal and human studies involving BM sample analysis focuses on the various parameters of interpretation of toxicological results: analytic limits, sampling location, pharmacokinetics, blood/BM concentration correlation, stability and postmortem redistribution. Tables summarizing the analytical conditions and quantification of 45 compounds from BM samples provide a useful tool for toxicologists. A specific section devoted to ethanol shows that, despite successful quantification, interpretation is highly dependent on postmortem interval. In conclusion, BM is an interesting alternative matrix, and further experimental data and validated assays are required to confirm its great potential relevance in forensic toxicology.

Regeneration of bone marrow after tibial ablation in immunocompromised rats is age dependent

Injuries to the marrow cavity result in rapid endosteal bone formation followed by remodeling and regeneration of the marrow. It is not known whether this process is affected by age, although marrow quality is markedly different in young and old animals. To test if marrow regeneration differs with age, we used a bone marrow ablation model that has been used to examine calcification, osteointegration of metal implants, and remodeling of bone graft substitutes. Marrow was ablated in the left tibia of seven immunocompromised rats (rNu/rNu) per time point. At 0, 7, 14, 21, 28, 35 and 42 days post-surgery, treated and contralateral tibias were harvested and fixed in buffered formalin. Both tibias were scanned using microCT and trabecular and cortical BVF calculated. Mid-sagittal histological sections of the treated limbs were stained with haematoxylin and eosin and BV/TV calculated. MicroCT and histomorphometry showed the greatest increase in bone formation was in young animals and was seen on day 7. Remodeling also occurred at an earlier time point in young rats. Bone formation peaked on day 7 in adult rats, but remodeling was slower than in young rats. Aged animals showed a delay in bone formation. Moreover, aged rats produced less primary bone than younger animals and remodeling was initiated later. These results show that response to injury in immunocompromised rats is reduced in aging and restoration of normal tissue quality is age-dependent.

A bone marrow F-18 FDG uptake exceeding the liver uptake may indicate bone marrow hyperactivity

OBJECTIVE

In clinical positron emission tomography (PET) studies for oncology, it is occasionally required to differentiate a diffuse increase in bone marrow (BM) F-18 fluoro-2-deoxyglucose (FDG) uptake due to the involvement of malignancy or hematopoietic disease and that due to the administration of hematopoietic cytokines, an inflammation reaction, or stimulation by some types of malignancy. The objectives of this study were to clarify the relationships between BM F-18 FDG uptake and blood parameters as well as age, and also to determine the degree of F-18 FDG accumulation that constitutes an abnormal level referring to blood parameters.

METHODS

Records of 65 patients, 32 with benign diseases and 33 with malignancies without metastasis in bone and liver until a half year after the PET examination, were analyzed retrospectively. Regions of interest were placed on the liver and the lower thoracic and lumbar vertebrae to measure the standardized uptake value (SUV), and vertebral SUVs were averaged as the BM SUV(mean). The BM SUV(mean) was divided by the liver SUV to calculate the BM/liver ratio. The relationships among the BM SUV(mean), or BM/liver ratio, and blood parameters and age were tested using multiple regression analysis.

RESULTS

In both patients with and without malignancy, a multiple regression model using the BM/liver ratio showed a higher coefficient of determination value than that using the BM SUV(mean), indicating that the correction by the liver SUV reduced the interindividual variation in the BM SUV(mean). The BM/liver ratio was negatively correlated with age (beta = -0.41 and -0.43, respectively) and positively correlated with serum C-reactive protein (CRP) level (beta = 0.39 and 0.46, respectively) in both groups of patients. Every patient with benign disease who had a ratio greater than or equal to 1 had an increased CRP level.

CONCLUSIONS

The BM F-18 FDG uptake depends on the patient's age and serum CRP level, both with and without malignancy. A BM F-18 FDG uptake greater than or equal to that of the liver may indicate BM activation.

[F-18]-fluorodeoxyglucose PET-CT of the normal prostate gland

OBJECTIVE

We determined the glucose metabolism and computed tomographic (CT) density of the normal prostate gland in relation to age and prostate size on [F-18] fluorodeoxyglucose positron emission tomography (PET)-CT.

METHODS

We determined the CT density (Hounsfield Units, HU) and glucose metabolism (standardized uptake value, SUV) of the normal prostate in 145 men (age range 22-97 years) on PET-CT scans which were performed for indications unrelated to prostate pathology. Correlations among SUV, HU, prostate size, and age were calculated using Pearson's correlation coefficients, scatter plots, and linear regression trend lines. The SUV and HU values were also compared among different primary cancer types using the Kruskal-Wallis test.

RESULTS

The population average and range of the normal prostate size were 4.3 +/- 0.5 cm (mean +/- SD) and 2.9-5.5 cm, respectively. The population average of mean and maximum CT densities was 36.0 +/- 5.1 HU (range 23-57) and 91.7 +/- 20.1 HU (range 62-211), respectively. The population average of mean and maximum SUV was 1.3 +/- 0.4 (range 0.1-2.7) and 1.6 +/- 0.4 (range 1.1-3.7), respectively. Mean SUV tended to decrease as the prostate size increased (r = -0.16, P = 0.058). Higher mean HU was correlated with higher mean SUV (r = 0.18, P = 0.033). The strongest association was observed between age and prostate size. The prostate gets larger as age increases (r = 0.32, P < 0.001). Prostate mean SUV, max SUV, mean HU, and max HU were not significantly different among different types of primary cancers.

CONCLUSIONS

Although the normal prostate size increases with age, it does not significantly affect the gland's metabolism and CT density, and therefore age-correction of these parameters may be unnecessary.