Radionuclide imaging of bone marrow disorders

Histopathological Confirmed Polycythemia Vera with Transformation to Myelofibrosis Depicted on [18F]FDG PET/CT

We present a case of a 59-year-old male diagnosed with polycythemia vera (PV) for many years, who presented with a relatively abrupt onset of heavy constitutional symptoms, including fatigue, night sweats, and a 10% weight loss over 6 weeks. Despite the known initial diagnosis of PV, the presence of profound B-symptoms prompted further investigation. A positron emission tomography/computed tomography (PET/CT) scan with 18F-Fluorodeoxyglucose ([18F]FDG) was performed to exclude malignant diseases. The [18F]FDG PET/CT revealed intense metabolic activity in the bone marrow of the proximal extremities and trunk skeleton, as well as a massively enlarged spleen with increased metabolic activity. Histopathologically, a transformation to myelofibrosis was revealed on a bone marrow biopsy. The case intends to serve as an exemplification for [18F]FDG PET/CT in PV with transformation to myelofibrosis (post-PV myelofibrosis).

18F-FDG PET/CT-Based Radiomics Nomogram for Prediction of Bone Marrow Involvement in Pediatric Neuroblastoma: A Two-Center Study

RATIONALE AND OBJECTIVES

To assess the predictive ability of an 18F-FDG PET/CT-based radiomics nomogram for bone marrow involvement in pediatric neuroblastoma.

MATERIALS AND METHODS

A total of 241 neuroblastoma patients who underwent 18F-FDG PET/CT at two medical centers were retrospectively evaluated. Data from center A (n = 200) were randomized into a training cohort (n = 140) and an internal validation cohort (n = 60), while data from center B (n = 41) constituted the external validation cohort. For each patient, two regions of interest were defined using the tumor and axial skeleton. The clinical factors and radiomics features were derived to construct the clinical and radiomics models. The radiomics nomogram was built by combining clinical factors and radiomics features. The area under the receiver operating characteristic curves (AUCs) were used to assess the performance of the models.

RESULTS

Radiomics models created from tumor and axial skeleton achieved AUCs of 0.773 and 0.900, and the clinical model had an AUC of 0.858 in the training cohort. By incorporating clinical risk factors and axial skeleton-based radiomics features, the AUC of the radiomics nomogram in the training cohort, internal validation cohort, and external validation cohort was 0.932, 0.887, and 0.733, respectively.

CONCLUSION

The axial skeleton-based radiomics model performed better than the tumor-based radiomics model in predicting bone marrow involvement. Moreover, the radiomics nomogram showed that combining axial skeleton-based radiomics features with clinical risk factors improved their performance.

Comparison of bone marrow biopsy and fluorodeoxyglucose-positron emission tomography for the assessment of bone marrow infiltration in children with Hodgkin's lymphoma

PURPOSE

To compare bone marrow biopsy (BMB) with [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (PET/CT) imaging in the demonstration of bone marrow involvement in children with Hodgkin's Lymphoma (HL) and to investigate the effectiveness of PET/CT imaging and thus the necessity for BMB at staging.

METHODS

Pediatric patients with HL, who underwent both bilateral iliac BMB and PET/CT imaging at disease staging were retrospectively analyzed. In determining bone marrow involvement (BMinv), BMB and/or first/follow-up PET/CT imaging were eligible for review.

RESULTS

Fifty-six patients were included. BMinv was detected by PET/CT imaging in 6/56 (10.7%), whereas the proportion was 3/56 (5.3%) in BMB specimens. Bone marrow biopsies and PET/CT images were concordant in 53/56 (94.6%) patients with BMB specimens missing three cases of BMinv detected by PET/CT. When diagnostic accuracy was calculated, sensitivity, specificity, positive predictive value and negative predictive values for PET/CT were 100%, 100%, 100%, 100%, respectively, and the same values for BMB were 50%, 100%, 100%, 94.3%, respectively.

CONCLUSIONS

The results of PET/CT and BMB for staging of pediatric HL patients were compatible, and PET/CT imaging was found to provide high diagnostic performance in determining BMinv. In keeping with earlier research, the current study showed that BMB may not be necessary in every patient at staging, and should be reserved for cases where PET/CT is inconclusive.

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.

Diagnostic Value of 18F-FDG PET/CT-Based Radiomics Nomogram in Bone Marrow Involvement of Pediatric Neuroblastoma

OBJECTIVES

To develop and validate an ¹⁸F-FDG PET/CT-based radiomics nomogram and evaluate the value of the ¹⁸F-FDG PET/CT-based radiomics nomogram for the diagnosis of bone marrow involvement (BMI) in pediatric neuroblastoma.

MATERIALS AND METHODS

A total of 144 patients with neuroblastoma (100 in the training cohort and 44 in the validation cohort) were retrospectively included. The PET/CT images of patients were visually assessed. The results of bone marrow aspirates or biopsies were used as the gold standard for BMI. Radiomics features and conventional PET parameters were extracted using the 3D slicer. Features were selected by the least absolute shrinkage and selection operator regression, and radiomics signature was constructed. Univariate and multivariate logistic regression analyses were applied to identify the independent clinical risk factors and construct the clinical model. Other different models, including the conventional PET model, combined PET-clinical model and combined radiomics model, were built using logistic regression. The combined radiomics model was based on clinical factors, conventional PET parameters and radiomics signature, which was presented as a radiomics nomogram. The diagnostic performance of the different models was evaluated by receiver operating characteristic (ROC) curves and decision curve analysis (DCA).

RESULTS

By visual assessment, BMI was observed in 80 patients. Four conventional PET parameters (SUVmax, SUVmean, metabolic tumor volume, and total lesion glycolysis) were extracted. And 15 radiomics features were selected to build the radiomics signature. The 11q aberration, neuron-specific enolase and vanillylmandelic acid were identified as the independent clinical risk factors to establish the clinical model. The radiomics nomogram incorporating the radiomics signature, the independent clinical risk factors and SUVmean demonstrated the best diagnostic value for identifying BMI, with an area under the curve (AUC) of 0.963 and 0.931 in the training and validation cohorts, respectively. And the DCA demonstrated that the radiomics nomogram was clinically useful.

CONCLUSION

The ¹⁸F-FDG PET/CT-based radiomics nomogram which incorporates radiomics signature, independent clinical risk factors and conventional PET parameters could improve the diagnostic performance for BMI of pediatric neuroblastoma without additional medical costs and radiation exposure.

The Diagnostic Value of 18F-FDG PET/CT Bone Marrow Uptake Pattern in Detecting Bone Marrow Involvement in Pediatric Neuroblastoma Patients

Objectives

To explore the diagnostic value of ¹⁸F-FDG PET/CT bone marrow uptake pattern (BMUP) in detecting bone marrow involvement (BMI) in pediatric neuroblastoma (NB) patients.

Methods

Ninety-eight NB patients were enrolled in BMI analysis. Four patterns of bone marrow uptake were categorized based on pretreatment ^cF-FDG PET/CT images. Some crucial inspection indexes and ¹⁸F-FDG PET/CT metabolic parameters were analyzed. The BMUP was divided into BMUP1, BMUP2, BMUP3, and BMUP4. Paired-like homeobox 2b (PHOX2B) of bone marrow and blood, bone marrow biopsy (BMB) result, and ¹⁸F-FDG PET/CT were compared to detect BMI. All patients were followed up for at least six months.

Results

BMUP had excellent consistency among different physicians. Kappa coefficients of two residents and two attending physicians and between the resident and attending physician, were 0.857, 0.891, and 0.845, respectively. The optimal cut-off value of SUVmax-Bone/Liver was 2.08 to diagnose BMI for BMUP3 patients, and the area under curve (AUC) was 0.873. AUC of PHOX2B of bone marrow (PHOX2B of BM), PHOX2B of blood, BMB, and ¹⁸F-FDG PET/CT were 0.916, 0.811, 0.806, and 0.904, respectively. There was no significant difference between PHOX2B of BM and PET/CT. Positive predictive value, negative predictive value, sensitivity, and specificity in diagnosis of BMI were 92.9%, 92.9%, 97.0%, and 83.9% for PET/CT and 96.7%, 80.6%, 89.6%, and 93.5% for PHOX2B of BM, respectively.

Conclusions

BMUP of pretreatment ¹⁸F-FDG PET/CT is a simple and practical method, which has a relatively high diagnostic efficiency in detecting BMI and might decrease unnecessary invasive inspections in some pediatric NB patients.

Disseminated focal 18F-fluoro-deoxyglucose uptake upon granulocyte colony-stimulating factor therapy mimicking malignant bone infiltration: case report of a patient with very severe aplastic anemia

Combined ¹⁸F-fluoro-deoxyglucose ([18F]FDG) positron emission tomography and computed tomography ([18F]FDG-PET/CT) is increasingly used for the diagnostic and therapeutic management of hematologic and non-hematologic malignancies. Here, we describe a unique case of a patient presenting with very severe aplastic anemia and a mediastinal mass showing disseminated hypermetabolic lesions of the bones after receiving granulocyte colony-stimulating factor (G-CSF), highly suspicious for disseminated metastatic lesions. A 71-year-old patient presented with a 3 week history of dyspnea and fatigue. Blood tests showed severe pancytopenia and iliac crest bone marrow biopsy revealed an extensively hypoplastic bone marrow. Diagnostic work-up by histology, conventional cytogenetics and flow cytometry confirmed the diagnosis of very severe aplastic anemia. Besides blood transfusions, the patient was treated with G-CSF. Furthermore, computed tomography revealed a suspect mass in the anterior mediastinum, presenting with moderate glucose metabolism in the subsequent [18F]FDG-PET/CT scan. In addition, multiple disseminated and highly metabolic bone lesions of primarily the ribs were detected, suspicious of malignant bone infiltration. Since physiologic bone marrow activation by G-CSF-stimulation could not be ruled out, G-CSF therapy was interrupted to repeat the PET/CT scan 10 days later. On the second [18F]FDG-PET/CT the moderately hypermetabolic mediastinal mass persisted. However, the initially FDG-avid bone lesions almost completely resolved, rendering the diagnosis of G-CSF-induced bone marrow hypermetabolism very likely without the need for further invasive diagnostic procedures. The mediastinal mass was thereafter histologically verified as thymoma. Interpretation of [18F]FDG-PET/CT in patients with aplastic anemia may be complicated by the frequent therapeutic use of G-CSF. With G-CSF, islets of residual bone marrow activity can be visualized on [18F]FDG-PET/CT images that might be misinterpreted as malignant bone infiltration. Repeating PET/CT scan after G-CSF discontinuation can prevent unnecessary invasive diagnostic procedures in these patients.

Peripheral Photopenia on Whole-Body PET/CT Imaging With 18F-FDG in Patients With Compartment Syndrome and Mesenteric Venous Thrombosis

We present 2 cases that demonstrate photopenia in peripheral areas on whole-body PET/CT imaging with F-FDG as a sign of absent perfusion with severe short-term complications. The scan of the first patient shows photopenia in the right ankle and foot, resulting from compartment syndrome, caused by hemolytic group A streptococcus bacteremia with endocarditis and septic emboli, necessitating lower leg amputation. The scan of the second patient shows photopenia in the transverse colon, resulting from mesenteric venous thrombosis caused by polycythemia vera, leading to necrosis and perforation of the transverse colon, necessitating transverse and right hemicolectomy.

Marrow outside marrow: imaging of extramedullary haematopoiesis

Extramedullary haematopoiesis (EMH) refers to the formation of non-neoplastic blood cell lines outside the bone marrow and is a common incidental finding when patients with haematological disorders are imaged. EMH presenting as mass (tumefactive EMH) has long been a radiological conundrum as it resembles neoplasms. Several imaging findings have been described in EMH, and these vary depending on the activity of the underlying haematopoiesis. The older lesions are easier to diagnose as they often demonstrate characteristic findings such as haemosiderin and fat deposition. In comparison, the newer, actively haematopoietic lesions often mimic neoplasms. Molecular imaging, particularly ^99mTc labelled sulphur colloid scintigraphy, may be helpful in such cases. Although imaging is extremely useful in detecting and characterising EMH, imaging alone is often non-diagnostic as no single mass shows all the typical findings. Hence, a judgement based on the clinical background, combination of imaging findings, and slow interval growth may be more appropriate and practical in making the correct diagnosis. In every case, an effort has to be made in providing an imaging-based diagnosis as it may prevent a potentially risky biopsy. When confident differentiation is not possible, biopsy has to be resorted to. This article describes the causes, pathophysiology, and theories underlying the genesis of EMH, followed by the general and location-specific imaging findings. The purpose is to provide a thorough understanding of the condition as well as enable the clinical radiologist in making an imaging-based diagnosis whenever possible and identify the situations where biopsy has to be performed.

3D Monte Carlo bone marrow dosimetry for Lu-177-PSMA therapy with guidance of non-invasive 3D localization of active bone marrow via Tc-99m-anti-granulocyte antibody SPECT/CT

BACKGROUND

The bone marrow (BM) is a main risk organ during Lu-177-PSMA ligand therapy of metastasized castration-resistant prostate cancer (mCRPC) patients. So far, BM dosimetry relies on S values, which are pre-computed for reference anatomies, simplified activity distributions, and a physiological BM distribution. However, mCRPC patients may show a considerable bone lesion load, which leads to a heterogeneous and patient-specific activity accumulation close to BM-bearing sites. Furthermore, the patient-specific BM distribution might be significantly altered in the presence of bone lesions. The aim was to perform BM absorbed dose calculations through Monte Carlo (MC) simulations and to investigate the potential value of image-based BM localization. This study is based on 11 Lu-177-PSMA-617 therapy cycles of 10 patients (10 first cycles), who obtained a pre-therapeutic Ga-68-PSMA-11 PET/CT; quantitative Lu-177 SPECT acquisitions of the abdomen 24 (+CT), 48, and 72 h p.i.; and a Lu-177 whole-body planar acquisition at 24 h post-therapy. Patient-specific 3D volumes of interest were segmented from the Ga-68-PSMA-11 PET/CT, filled with activity information from the Lu-177 data, and imported into the FLUKA MC code together with the patient CT. MC simulations of the BM absorbed dose were performed assuming a physiological BM distribution according to the ICRP 110 reference male (MC1) or a displacement of active BM from the direct location of bone lesions (MC2). Results were compared with those from S values (SMIRD). BM absorbed doses were correlated with the decrease of lymphocytes, total white blood cells, hemoglobin level, and platelets. For two patients, an additional pre-therapeutic Tc-99m-anti-granulocyte antibody SPECT/CT was performed for BM localization.

RESULTS

Median BM absorbed doses were 130, 37, and 11 mGy/GBq for MC1, MC2, and SMIRD, respectively. Significant strong correlation with the decrease of platelet counts was found, with highest correlation for MC2 (MC1: r = - 0.63, p = 0.04; MC2: r = - 0.71, p = 0.01; SMIRD: r = - 0.62, p = 0.04). For both investigated patients, BM localization via Tc-99m-anti-granulocyte antibody SPECT/CT indicated a displacement of active BM from the direct location of lesions similar to model MC2 and led to a reduction in the BM absorbed dose of 40 and 41% compared to MC1.

CONCLUSION

Higher BM absorbed doses were observed for MC-based models; however, for MC2, all absorbed doses were still below 2 Gy. MC1 resulted in critical values for some patients, but is suspected to yield strongly exaggerated absorbed doses by neglecting bone marrow displacement. Image-based BM localization might be beneficial, and future studies are recommended to support an improvement for the prediction of hematoxicities.

Development of an inflammation imaging tracer, 111In-DOTA-DAPTA, targeting chemokine receptor CCR5 and preliminary evaluation in an ApoE-/- atherosclerosis mouse model

BACKGROUND

Chemokine receptor 5 (CCR5) plays an important role in atherosclerosis. Our objective was to develop a SPECT tracer targeting CCR5 for imaging plaque inflammation by radiolabeling D-Ala-peptide T-amide (DAPTA), a CCR5 antagonist, with 111In.

METHODS

1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated DAPTA (DOTA-DAPTA) was labeled with 111In. Cell uptake studies were conducted in U87-CD4-CCR5 and U87-MG cells. Biodistribution was determined in C57BL/6 mice. Autoradiography, en face and Oil Red O (ORO) imaging studies were performed in ApoE-/- mice.

RESULTS

DOTA-DAPTA was radiolabeled with 111In with high radiochemical purity (> 98%) and specific activity (70 MBq·nmol). 111In-DOTA-DAPTA exhibited fast blood and renal clearance and high spleen uptake. The U87-CD4-CCR5 cells had significantly higher uptake in comparison to the U87-MG cells. The cell uptake was reduced by three times with DAPTA, indicating the receptor specificity of the uptake. Autoradiographic images showed significantly higher lesion uptake of 111In-DOTA-DAPTA in ApoE-/- mice than that in C57BL/6 mice. The tracer uptake in 4 month old ApoE-/- high fat diet (HFD) mice with blocking agent was twofold lower than the same mice without the blocking agent, demonstrating the specificity of the tracer for the CCR5 receptor.

CONCLUSION

111In-DOTA-DAPTA, specifically targeting chemokine receptor CCR5, is a potential SPECT agent for imaging inflammation in atherosclerosis.

Hereditary Spherocytosis Presenting as Diffuse Bone Marrow Activation and Splenomegaly on PSMA-Targeted 18F-DCFPyL PET/CT

We present the case of a 71-year-old man with Gleason 3 + 3 = 6 pT2N0MxR0 adenocarcinoma of the prostate who presented with rising PSA level 16 years after radical prostatectomy. PSMA-targeted F-DCFPyL PET/CT was performed, which demonstrated recurrent disease in the prostatectomy bed as well as splenomegaly and mild-diffuse bone marrow activation, consistent with the patient's history of hereditary spherocytosis. We briefly review the clinical characteristics of hereditary spherocytosis, its appearance on molecular imaging studies, the normal biodistribution of F-DCFPyL, and the PSMA-RADS scoring system for characterizing findings on PSMA-targeted PET imaging.

Evaluation of technetium-99m metastable nanocolloid as an imaging agent for performing milk scans

OBJECTIVE

The aim of this study was to determine whether technetium-99m (Tc) nanocolloid was a suitable alternative tracer for carrying out milk scan studies in pediatric patients.

PARTICIPANTS AND METHODS

Twenty-seven milk scans performed with Tc nanocolloid were retrospectively assessed for identification of significant esophageal hold-up, gastroesophageal reflux, pulmonary aspiration, and gastric emptying (GE). Scans were also assessed for liver, spleen, and bone marrow uptake. GE results were compared with those of 27 randomly selected normal GE studies carried out using Tc tin colloid.

RESULTS

None of the studies had liver, spleen, or bone marrow uptake, and all studies were interpretable. Significant esophageal hold-up and gastroesophageal reflux was observed in 11 and 48% of the patients, respectively. Only one patient had evidence of pulmonary aspiration, and all patients had normal GE at 2 h after radiolabeled milk ingestion. The average rate of GE at 2 h was faster in the Tc nanocolloid group compared with the Tc tin colloid group (8.85% retained±8.96% vs. 15.48% retained±10.52%, P=0.016).

CONCLUSION

Our findings show that Tc nanocolloid is technically a suitable alternative to Tc sulfur colloid for performing milk scans. However, we could not conclude with certainty on the comparison of the GE rates of Tc nanocolloid and Tc tin colloid. This was because of the variability in the two population groups as well as the fact that the milk that was used in each patient was individualized to the patient and was not standardized.

IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the Education Community (IUPAC Technical Report)

The IUPAC (International Union of Pure and Applied Chemistry) Periodic Table of the Elements and Isotopes (IPTEI) was created to familiarize students, teachers, and non-professionals with the existence and importance of isotopes of the chemical elements. The IPTEI is modeled on the familiar Periodic Table of the Chemical Elements. The IPTEI is intended to hang on the walls of chemistry laboratories and classrooms. Each cell of the IPTEI provides the chemical name, symbol, atomic number, and standard atomic weight of an element. Color-coded pie charts in each element cell display the stable isotopes and the relatively long-lived radioactive isotopes having characteristic terrestrial isotopic compositions that determine the standard atomic weight of each element. The background color scheme of cells categorizes the 118 elements into four groups: (1) white indicates the element has no standard atomic weight, (2) blue indicates the element has only one isotope that is used to determine its standard atomic weight, which is given as a single value with an uncertainty, (3) yellow indicates the element has two or more isotopes that are used to determine its standard atomic weight, which is given as a single value with an uncertainty, and (4) pink indicates the element has a well-documented variation in its atomic weight, and the standard atomic weight is expressed as an interval. An element-by-element review accompanies the IPTEI and includes a chart of all known stable and radioactive isotopes for each element. Practical applications of isotopic measurements and technologies are included for the following fields: forensic science, geochronology, Earth-system sciences, environmental science, and human health sciences, including medical diagnosis and treatment.

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.

18F-3'-Deoxy-3'-Fluorothymidine Positron Emission Tomography Imaging for the Prediction of Acute Graft-Versus-Host Disease in Mouse Hematopoietic Stem Cell Transplant Models

Acute graft-versus-host disease (aGVHD) remains a barrier to the success of allogeneic hematopoietic stem cell transplantation. In mice, studies have demonstrated that donor conventional T cells traffic into host secondary lymphoid tissues early after transplant, and that this process is critical for the development of disease. As a result, the measurement of cellular proliferation within lymphoid sites early after transplant might be a useful approach for predicting aGVHD in humans. 18F-3'-deoxy-3'-fluorothymidine (FLT) positron emission tomography (PET) imaging has recently emerged as a functional imaging modality in oncology patients. FLT, a thymidine analog, is incorporated into replicating DNA and is thus an indirect marker of cellular proliferation. Here we report that FLT PET imaging can differentiate mice receiving alloreactive T cells and destined to develop lethal aGVHD from control mice. Mice receiving allogeneic T cells demonstrated a stronger FLT signal within the peripheral lymph nodes compared with control mice at all time points after transplant. In addition, allogeneic T cell recipients transiently demonstrated stronger FLT uptake within the spleen. Importantly, these differences were apparent before the development of clinical disease. In contrast, the FLT signal within the host bowel, an important aGVHD target organ, was more variable after transplant and was not consistently different between aGVHD mice and control mice. Collectively, these findings suggest that the imaging of patient lymphoid sites using existing FLT PET technology might be useful for predicting aGVHD in the clinical setting.

99mTc-Sulfur Colloid Bone Marrow Scintigraphy in Diagnosis of Diffuse Pulmonary Extramedullary Hematopoiesis Secondary to Myelofibrosis

Our objective was to define the role of combined ^99mTc-sulfur colloid bone marrow (SC BM) scintigraphy, SPECT or SPECT/CT, and chest CT in diagnosing diffuse pulmonary extramedullary hematopoiesis (PEMH) in patients with myelofibrosis. Methods: We retrospectively reviewed ^99mTc-SC BM scintigraphy scans performed at our institution for the diagnosis of diffuse PEMH, as well as accompanying chest CT and SPECT/CT imaging findings. Relevant clinical information, including respiratory manifestations, pulmonary hypertension, and subjective response to whole-lung radiation therapy, was also summarized. Results: Twenty-two myelofibrosis patients with 27 ^99mTc-SC BM scintigraphy scans were diagnosed with diffuse PEMH. In 21 patients (95%) with accompanying chest CT and SPECT/CT scans, the most common CT findings were ground-glass opacity, interstitial infiltration, and pleural effusion. Of 20 patients (91%) who underwent 2-dimensional echocardiography studies, 12 (55%) were diagnosed with pulmonary hypertension. All 12 patients exhibited the aforementioned nonspecific CT imaging findings, with 8 (66%) of them presenting with respiratory symptoms, including dyspnea, shortness of breath, and cough. In the remaining 8 patients, without pulmonary hypertension, half had similar respiratory symptoms. Fourteen patients (64%) of this cohort received whole-lung radiation therapy, of whom 7 (50%) experienced symptom relief after therapy. Conclusion: Nonspecific respiratory symptoms should raise concern about pulmonary hypertension and diffuse PEMH in patients with advanced-stage myelofibrosis. Combined ^99mTc-SC BM scintigraphy and SPECT/CT is a promising noninvasive imaging tool to diagnose this rare clinical entity.Key Words: hematology; respiratory; SPECT/CT; pulmonary hematopoiesis; Tc-99m sulfur colloid scintigraphy; myelofibrosis.

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.

18F-FDG PET/CT findings in hepatosplenic Gamma-Delta T-cell lymphoma: case reports and review of the literature

Hepatosplenic Gamma Delta T cell lymphoma (γδHSTL) is a rare, highly aggressive, and rapidly lethal T cell lymphoma which manifests ¹⁸F-FDG PET/CT findings that can mimic benign conditions. Patients with γδHSTL present with unexplained symptoms of a hematologic malignancy like the B symptoms of lymphoma including weight loss, fevers, and night sweats, as well as, splenomegaly and hepatomegaly. Thrombocytopenia, anemia, or neutropenia are also common due to spleen, liver and bone marrow involvement. The peripheral blood, however, typically does not show abnormal T cells. The clinical and ¹⁸F-FDG PET/CT findings are presented for 3 patients with γδHSTL. Patients with γδHSTL may have a normal ¹⁸F-FDG PET/CT or an ¹⁸F-FDG PET/CT with any combination of the three findings: splenomegaly with intense FDG uptake; hepatomegaly with increased FDG uptake; and diffuse, increased FDG uptake in the bone marrow. Importantly, lymphadenopathy is usually absent, and most patients show morphologically normal lymph nodes with normal FDG uptake. Due to the aggressive nature of the disease, γδHSTL is a critical diagnosis to consider in patients who present with clinical signs of suspected hematologic malignancy and variable ¹⁸F-FDG PET/CT findings. The absence of lymphadenopathy and normal FDG uptake in lymph nodes are typical pertinent negative findings that differentiate γδHSTL from other lymphomas. A bone or liver biopsy is frequently necessary to establish the diagnosis and should be recommended.

Craniofacial Manifestations of Systemic Disorders: CT and MR Imaging Findings and Imaging Approach

Many systemic diseases or conditions can affect the maxillofacial bones; however, they are often overlooked or incidentally found at routine brain or head and neck imaging performed for other reasons. Early identification of some conditions may significantly affect patient care and alter outcomes. Early recognition of nonneoplastic hematologic disorders, such as thalassemia and sickle cell disease, may help initiate earlier treatment and prevent serious complications. The management of neoplastic diseases such as lymphoma, leukemia, or Langerhans cell histiocytosis may be different if diagnosed early, and metastases to the maxillofacial bones may be the first manifestation of an otherwise occult neoplasm. Endocrinologic and metabolic disorders also may manifest with maxillofacial conditions. Earlier recognition of osteoporosis may alter treatment and prevent complications such as insufficiency fractures, and identification of acromegaly may lead to surgical treatment if there is an underlying growth hormone-producing adenoma. Bone dysplasias sometimes are associated with skull base foraminal narrowing and subsequent involvement of the cranial nerves. Inflammatory processes such as rheumatoid arthritis and sarcoidosis may affect the maxillofacial bones, skull base, and temporomandibular joints. Radiologists should be familiar with the maxillofacial computed tomographic and magnetic resonance imaging findings of common systemic disorders because these may be the first manifestations of an otherwise unrevealed systemic process with potential for serious complications. Online supplemental material is available for this article. ^©RSNA, 2018.

Circulating Progenitor Cell Response to Exercise in Wheelchair Racing Athletes

INTRODUCTION

Circulating progenitor cells (CPC) are a heterogeneous population of stem/progenitor cells in peripheral blood that participate in tissue repair. CPC mobilization has been well characterized in able-bodied persons but has not been previously investigated in wheelchair racing athletes. The purpose of this study was to characterize CPC and CPC subpopulation mobilization in elite wheelchair racing athletes in response to acute, upper-extremity aerobic exercise to determine whether CPC responses are similar to ambulatory populations.

METHODS

Eight participants (three females; age = 27.5 ± 4.0 yr, supine height = 162.5 ± 18.6 cm, weight = 53.5 ± 10.9 kg, V˙O2peak = 2.4 ± 0.62 L·min, years postinjury = 21.5 ± 6.2 yr) completed a 25-km time trial on a road course. Blood sampling occurred before and immediately after exercise for quantification of CPC (CD34), hematopoietic stem and progenitor cells (HSPC) (CD34/CD45), hematopoietic stem cells (HSC) (CD34/CD45/CD38), CD34 adipose tissue (AT)-derived mesenchymal stromal cells (MSC) (CD45/CD34/CD105/CD31), CD34 bone marrow (BM)-derived MSC (CD45/CD34/CD105/CD31), and endothelial progenitor cells (EPC) (CD45/CD34/VEGFR2) via flow cytometry. Blood lactate was measured before and after trial as an indicator of exercise intensity.

RESULTS

CPC concentration increased 5.7-fold postexercise (P = 0.10). HSPC, HSC, EPC, and both MSC populations were not increased postexercise. Baseline HSPC populations were significantly positively correlated to absolute V˙O2peak (rho = 0.71, P < 0.05) with HSC trending to positively correlate to V˙O2peak (rho = 0.62, P = 0.10). AT-MSC populations were trending to be negatively correlated to baseline V˙O2peak (rho = -0.62, P = 0.058). The change in CPC, EPC, and AT-MSC pre- and postexercise significantly positively correlated to the change in lactate concentrations (rho = 0.91 P = 0.002, 0.71 P = 0.047, 0.81 P = 0.02, respectively, all P < 0.05).

CONCLUSION

These data suggest that CPC content in wheelchair racing athletes is related to cardiorespiratory fitness, and responses to exercise are positively related to exercise intensity.

Radionuclides transform chemotherapeutics into phototherapeutics for precise treatment of disseminated cancer

Most cancer patients succumb to disseminated disease because conventional systemic therapies lack spatiotemporal control of their toxic effects in vivo, particularly in a complicated milieu such as bone marrow where progenitor stem cells reside. Here, we demonstrate the treatment of disseminated cancer by photoactivatable drugs using radiopharmaceuticals. An orthogonal-targeting strategy and a contact-facilitated nanomicelle technology enabled highly selective delivery and co-localization of titanocene and radiolabelled fluorodeoxyglucose in disseminated multiple myeloma cells. Selective ablation of the cancer cells was achieved without significant off-target toxicity to the resident stem cells. Genomic, proteomic and multimodal imaging analyses revealed that the downregulation of CD49d, one of the dimeric protein targets of the nanomicelles, caused therapy resistance in small clusters of cancer cells. Similar treatment of a highly metastatic breast cancer model using human serum albumin-titanocene formulation significantly inhibited cancer growth. This strategy expands the use of phototherapy for treating previously inaccessible metastatic disease.

Imaging of subclinical haemopoiesis after stem-cell transplantation in patients with haematological malignancies: a prospective pilot study

BACKGROUND

Haemopoietic stem-cell transplantation (HSCT) eradicates host haemopoiesis before venous infusion of haemopoietic stem cells (HSCs). The pathway to cellular recovery has been difficult to study in human beings because of risks associated with interventions during aplasia. We investigated whether 18F-fluorothymidine (18F-FLT) imaging was safe during allogenic HSCT and allowed visualisation of early cellular proliferation and detection of patterns of cellular engraftment after HSCT.

METHODS

Eligible patients were aged 18-55 years, had high-risk haematological malignancies. All patients underwent myeloablation followed by HSCT. The imaging primary endpoint was detection of early subclinical engraftment after HSCT with 18F-FLT PET or CT. Imaging was done 1 day before and 5 or 9, and 28 days, and 1 year after HSCT. This study is registered with ClinicalTrials.gov, number NCT01338987.

FINDINGS

Between April 1, 2014, and Dec 31, 2015, 23 patients were enrolled and assessable for toxic effects after completing accrual. 18F-FLT was not associated with any adverse events or delayed engraftment. 18F-FLT imaging objectively identified subclinical bone-marrow recovery within 5 days of HSC infusion, which was up to 20 days before engraftment became clinically evident. Quantitatively, 18F-FLT intensity differed significantly between myeloablative infusion before HSCT and subclinical HSC recovery (p=0·00031). 18F-FLT biodistribution over time revealed a previously unknown path of cellular recovery of haemopoiesis in vivo that mirrored fetal ontogeny.

INTERPRETATION

18F-FLT allowed quantification and tracking of subclinical bone-marrow repopulation in human beings and revealed new insights into the biology of HSC recovery after HSCT.

FUNDING

National Institutes of Health, Ben's Run/Ben's Gift, Albert and Elizabeth Tucker Foundation, Mex Frates Leukemia Fund, Jones Family fund, and Oklahoma Center for Adult Stem Cell Research.

Utility of 111In-Cl3 scintigraphy for differentiating bone marrow reconversion

Indium chloride (111In-Cl3) scintigraphy has been used to evaluate various hematological diseases for many years. However, there have been few reports on patients with bone marrow reconversion showing high uptake in 111In-Cl3 scintigraphy. Herein, we report a case of a 68-year-old man with esophageal cancer who underwent 18F-FDG PET/CT for staging of the disease. 18F-FDG PET/CT demonstrated high uptake in the first lumbar vertebral body, which was difficult to distinguish bone metastasis and bone marrow reconversion. 111In-Cl3 scintigraphy demonstrated specific findings with high uptake in the lesion, indicating bone marrow hyperplasia or reconversion.

Assessing Bone Marrow Activity in Patients with Myelofibrosis: Results of a Pilot Study of 18F-FLT PET

An emerging noninvasive approach to assess tissue proliferation uses the PET tracer 3'-deoxy-3'-¹⁸F-fluorothymidine (¹⁸F-FLT). To evaluate the diagnostic value of this technique in myelofibrosis, ¹⁸F-FLT PET imaging results were compared with bone marrow histology and bone marrow scintigraphy (BMS), the gold standard techniques in this clinical situation. Methods: Fifteen patients with histology-proven myelofibrosis were included consecutively in the study. Tracers' distributions were assessed using a visual grading assessment score of the uptake in the axial skeleton, proximal and distal limbs, liver, and spleen. This visual score was used to define patterns of tracer distribution and to compare the information provided either by PET or by BMS. A semiquantitative analysis with determination of SUV_max in the same localizations was performed for ¹⁸F-FLT PET. Results: The histology grade of fibrosis correlated with the SUV_max in the axial skeleton (spine and iliac crests) and proximal limbs. ¹⁸F-FLT uptake in these areas was much lower in patients with grade 3 fibrosis than in patients with grade 1 or 2 fibrosis. ¹⁸F-FLT PET showed the same distribution of uptake as BMS in 13 of 14 patients (1 patient did not undergo BMS). In 1 patient, ¹⁸F-FLT PET clearly showed an intense abnormal splenic uptake, whereas spleen uptake was inconclusive with BMS. Conclusion:¹⁸F-FLT PET appears to be a reliable and convenient technique to assess hematopoietic activity in bone marrow. It yields results close to those observed with BMS. In our study population, ¹⁸F-FLT uptake in the axial skeleton and proximal limbs assessed by SUV_max correlated with the grade of fibrosis. Thus, ¹⁸F-FLT PET may be a useful tool to measure the severity of myelofibrosis, and to monitor noninvasively the patients' status during follow-up. Finally, ¹⁸F-FLT PET may be foreseen as an alternative to BMS.

Nuclear medicine imaging of multiple myeloma, particularly in the relapsed setting

Multiple myeloma (MM) is characterized by a monoclonal plasma cell population in the bone marrow. Lytic lesions occur in up to 90 % of patients. For many years, whole-body X-ray (WBX) was the method of choice for detecting skeleton abnormalities. However, the value of WBX in relapsing disease is limited because lesions persist post-treatment, which restricts the capacity to distinguish between old, inactive skeletal lesions and new, active ones. Therefore, alternative techniques are necessary to visualize disease activity. Modern imaging techniques such as magnetic resonance imaging, positron emission tomography and computed tomography offer superior detection of myeloma bone disease and extramedullary manifestations. In particular, the properties of nuclear imaging enable the identification of disease activity by directly targeting the specific cellular properties of malignant plasma cells. In this review, an overview is provided of the effectiveness of radiopharmaceuticals that target metabolism, surface receptors and angiogenesis. The available literature data for commonly used nuclear imaging tracers, the promising first results of new tracers, and our pilot work indicate that a number of these radiopharmaceutical applications can be used effectively for staging and response monitoring of relapsing MM patients. Moreover, some tracers can potentially be used for radio immunotherapy.

Copper-64 labeled liposomes for imaging bone marrow

INTRODUCTION

Bone marrow is the soft tissue compartment inside the bones made up of hematopoietic cells, adipocytes, stromal cells, phagocytic cells, stem cells, and sinusoids. While [¹⁸F]-FLT has been utilized to image proliferative marrow, to date, there are no reports of particle based positron emission tomography (PET) imaging agents for imaging bone marrow. We have developed copper-64 labeled liposomal formulation that selectively targets bone marrow and therefore serves as an efficient PET probe for imaging bone marrow.

METHODS

Optimized liposomal formulations were prepared with succinyl PE, DSPC, cholesterol, and mPEG-DSPE (69:39:1:10:0.1) with diameters of 90 and 140nm, and were doped with DOTA-Bn-DSPE for stable ⁶⁴Cu incorporation into liposomes.

RESULTS

PET imaging and biodistribution studies with ⁶⁴Cu-labeled liposomes indicate that accumulation in bone marrow was as high as 15.18±3.69%ID/g for 90nm liposomes and 7.01±0.92%ID/g for 140nm liposomes at 24h post-administration. In vivo biodistribution studies in tumor-bearing mice indicate that the uptake of 90nm particles is approximately 0.89±0.48%ID/g in tumor and 14.22±8.07%ID/g in bone marrow, but respective values for Doxil® like liposomes are 0.83±0.49%ID/g and 2.23±1.00%ID/g.

CONCLUSION

Our results indicate that our novel PET labeled liposomes target bone marrow with very high efficiency and therefore can function as efficient bone marrow imaging agents.

Assessment of sites of marrow and extramedullary hematopoiesis by hybrid imaging in primary myelofibrosis patients

We investigated noninvasive procedures by hybrid imaging to assess the sites of active or inactive hematopoiesis in patients with primary myelofibrosis (PMF). To this end, we used two radionuclides, technetium 99m ((99m) Tc) and indium 111-chloride ((111) In-Cl3 ), coupled with single-photon emission tomography/computed tomography (SPECT/CT). We studied five patients with PMF and one with secondary myelofibrosis (MF). The classical pattern of lower fixation of both tracers at the axial skeleton where the myelofibrotic process occurs and the reactivation of sites of active hematopoiesis at the distal skeleton were confirmed. Coupling both radionuclides to SPECT/CT imaging allowed for more precise visualization of the sites of extramedullary hematopoiesis as those observed in the spleen and liver. Splenic high uptake of (111) In-Cl3 coupled with SPECT/CT represents a pathognomonic feature of PMF. We conclude that, the hybrid imaging procedures that we studied might constitute an alternative noninvasive method for the screening of the whole-body marrow and, by this way, to assess the impact of targeted therapies in PMF patients in whom it is well known that the distribution of the hematopoietic active areas is disturbed. Hybrid imaging could also be useful for diagnostic purposes in cases of early PMF or in suspected cases of myelofibrosis secondary to polycythemia vera or essential thrombocythemia.

18F-FDG PET increases visibility of bone lesions in relapsed multiple myeloma: is this hypoxia-driven?

INTRODUCTION

Whole-body x-ray (WBX) is used for detecting skeleton abnormalities in patients with multiple myeloma (MM). An alternative might be 18F-FDG PET, which makes use of metabolic changes of malignant cells. The aims of this study were to evaluate whether 18F-FDG PET detects more lesions compared with WBX in patients with relapsing MM and to define its prognostic value. In addition 1-α-D-(5-deoxy-5-[F]-fluoroarabinofuranosyl)-2-nitroimidazole (18F-FAZA) scan and immunohistochemical staining on bone marrow were performed to define whether FDG uptake coincides with angiogenesis-related tumor hypoxia.

PATIENTS AND METHODS

18F-FDG PET (n = 44) and 18F-FAZA-PET (n = 5) were performed in patients with relapsed MM. Bone marrow biopsies (n = 20) were evaluated for hypoxia inducible factors (HIF) 1α and 2α, vascular endothelial growth factor, glucose transport proteins 1 and 3, and the microvessel density.

RESULTS

New lesions were more frequently demonstrated on 18F-FDG PET than on WBX (P = 0.000001). 18F-FDG PET was not predictive for progression-free survival and overall survival. Immunohistochemical staining on bone marrow biopsies demonstrated a significant increase in microvessel density and elevated expression of vascular endothelial growth factor, HIF-2α, and glucose transport protein 3 by the malignant plasma cells. However, HIF-1α expression and 18F-FAZA scan results were negative.

CONCLUSIONS

Our results demonstrate that 18F-FDG PET is relevant for diagnostic purposes compared with WBX in relapsing MM. The enhanced uptake of 18F-FDG PET is likely related to the activation of the HIF-2α signaling pathway but probably independent of hypoxia-induced signaling in view of the negative findings on both 18F-FAZA-PET and HIF-1α expression.

FDG-PET/CT findings in systemic mastocytosis: a French multicentre study

INTRODUCTION

Mastocytosis is a clonal haematological disease characterized by uncontrolled proliferation and the activation of mast cells. The value of FDG-PET/CT (FDG-PET) in mastocytosis has yet to be determined.

METHODS

We retrospectively identified patients with an established diagnosis of systemic mastocytosis (SM), according to the WHO criteria, who underwent PET using the French Reference Centre for Mastocytosis database. Semi-quantitative and visual analysis of FDG-PET was performed and compared to the clinico-biological data.

RESULTS

Our cohort included 19 adult patients, median age 65 years [range 58-74], including three with smouldering SM (SSM), three with aggressive SM (ASM), 10 with an associated clonal haematological non-mast-cell lineage disease (SM-AHNMD), and three with mast cell sarcoma (MCS). FDG-PET was performed at the time of the SM diagnosis (15/19), to evaluate lymph node (LN) activity (3/19) or the efficacy of therapy (1/19). FDG uptake was observed in the bone marrow (BM) (9/19, 47%), LN (6/19, 32%), spleen (12/19, 63%), or liver (1/19, 5%). No significant FDG uptake was observed in the SSM and ASM patients. A pathological FDG uptake was observed in the BM of 6/10 patients with SM-AHNMD, appearing as diffuse and homogeneous, and in the LN of 5/10 patients. All 3 MCS patients showed intense and multifocal BM pathological uptake, mimicking metastasis. No correlation was found between the FDG-PET findings and serum tryptase levels, BM mast cell infiltration percentage, and CD30 and CD2 expression by mast cells.

CONCLUSIONS

FDG uptake does not appear to be a sensitive marker of mast cell activation or proliferation because no significant FDG uptake was observed in most common forms of mastocytosis (notably purely aggressive SM). However, pathological FDG uptake was observed in the SM-AHNMD and in MCS cases, suggesting a role of FDG-PET in their early identification and as a tool of therapeutic assessment in this subgroup of patients.

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.

Proliferative and Glycolytic Assessment of the Whole-Body Bone Marrow Compartment

OBJECTIVE

Quantitative assessment of active bone marrow (BM) in vivo is yet to be well-defined. This study aims to compare total body BM volume estimations obtained from use of both18F-FLT PET/CT and 18F-FDG PET/CT in order to consolidate higher cellular proliferation rates with imaging the highly active red BM in pancreatic cancer.

METHODS

This phase I pilot study includes seven patients with pancreatic cancers who underwent both 18F-FLT and 18F-FDG imaging each acquired within a week's duration. A CT-based classifier is used for segmenting bone into cortical and trabecular regions. The total BM volume is determined through statistical thresholding on PET activity found within the trabecular bone.

RESULTS

Results showed that 18F-FLT measures of red BM volume (RBV) were higher than those obtained from 18F-FDG (∆=89.21 ml). RBV obtained using 18F-FLT in males were found to have high correlation with measured weight (R2=0.61) and BMI (R2=0.70). The red BM fraction obtained from 18F-FLT was significantly different between males and females, with females showing much higher red bone matter within the trabecular bone (p<0.05). In contrast to 18F-FLT, 18F-FDG BM measurements showed that RBV was significantly different between males and females (p<0.05). Results also show that spinal activity SUV threshold for red BM segmentation is significantly different between 18F-FLT PET and 18F-FDG PET (p<0.05).

CONCLUSION

By combining 18F-FLT-PET and 18F-FDG-PET, this study provides useful insights for in vivo BM estimation through its proliferative and glycolytic activities.

Assessment of bone marrow inflammation in patients with myelofibrosis: an 18F-fluorodeoxyglucose PET/CT study

PURPOSE

Myelofibrosis is a haematopoietic stem cell neoplasm characterized by bone marrow inflammation, reactive marrow fibrosis and extramedullary haematopoiesis. The aim of this study was to determine if (18)F-FDG PET/CT can be used to noninvasively visualize and quantify the extent and activity of bone marrow involvement.

METHODS

In 30 patients, the biodistribution of (18)F-FDG was analysed by measuring the standardized uptake value in the bone marrow compartment and spleen. Imaging findings were compared with laboratory, cytogenetic and histopathological data.

RESULTS

Retention of (18)F-FDG was observed in bone marrow and spleen. Bone marrow involvement varied, ranging from mildly increased uptake in the central skeleton to extensive uptake in most parts of the skeleton. The extent of bone marrow involvement decreased over time from initial diagnosis (r s  = -0.43, p = 0.019). Metabolic activity of the bone marrow decreased as the histopathological grade of fibrosis increased (r s  = -0.37, p = 0.04). There was a significant positive correlation between the metabolic activity of the bone marrow and that of the spleen (p = 0.04).

CONCLUSION

(18)F-FDG PET/CT is as a promising technique for the quantitation of bone marrow inflammation in myelofibrosis. Our data indicate that the intensity of bone marrow (18)F-FDG uptake decreases as bone marrow fibrosis increases. Further evaluation in prospective studies is required to determine the potential clinical impact and prognostic significance of PET.

Heterogeneous bone marrow uptake on interim 18F-fluorodeoxyglucose positron emission tomography for lymphoma mimicking disease progression: a case report

Introduction

The use of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) scanning for baseline staging and assessment of treatment response for higher grade lymphomas is considered to be the standard of care. Evaluation of lymphomatous bone marrow infiltration on ¹⁸F-FDG PET can usually distinguish between normal regenerating marrow following chemotherapy by a characteristic pattern of uptake.

Case presentation

Here we report the case of a 51-year-old Caucasian woman with mixed low- and high-grade lymphoma with biopsy confirmed marrow infiltration. An interim post-three cycle chemotherapy ¹⁸F-FDG PET scan revealed apparent progression of marrow disease. Subsequent investigations were performed including bone marrow biopsies, repeat ¹⁸F-FDG PET scanning and a white cell scan. These revealed the interim ¹⁸F-FDG PET scan appearance was due to a highly unusual pattern of scattered islands of regenerating normal marrow, rather than progressive lymphoma.

Conclusions

Our case report highlights that apparent severe bone marrow abnormalities on ¹⁸F-FDG PET scans in lymphoma patients treated with chemotherapy are not always due to disease. Clinicians should retain a high index of suspicion for benign causes when ¹⁸F-FDG PET scan results appear incongruent with clinical response.

The value of semiquantitative analysis in identifying diffuse bone marrow involvement in follicular lymphoma

AIM

The aim of the study was to investigate the value of fluorine-18-fluorodeoxyglucose ((18)F-FDG)-PET/computed tomography (CT) in identifying diffuse bone marrow (BM) involvement in follicular lymphoma using semiquantitative assessment.

METHODS

This is a retrospective analysis of 41 patients with grade 1-3a follicular lymphoma who underwent (18)F-FDG-PET/CT, contrast-enhanced CT and bone marrow trephine biopsy (BMB) as part of staging. BM involvement on PET/CT was assessed by visual and semiquantitative analysis. Standardized uptake values (SUVmax) were measured at the sternum, at both iliac blades and at the T12 vertebra. An average of these four measurements was recorded as SUVav. The single highest overall SUVmax for the four bone sites, the SUVav and the ratios SUVav/mediastinal blood pool (MBP) and SUVav/liver were compared with the BMB result.

RESULTS

Focal bone uptake was identified on (18)F-FDG-PET/CT by visual analysis in six patients, including two cases in which the BMB was negative. Assessment of diffuse BM involvement on (18)F-FDG-PET/CT by visual analysis had a sensitivity and specificity of 31 and 92%, respectively. Semiquantitative analysis resulted in an improved sensitivity and specificity of 58 and 96%, respectively, when using SUVav greater than or equal to 2 as the cutoff. Using the ratio SUVav/MBP greater than or equal to 1 the sensitivity of (18)F-FDG-PET/CT to detect BM involvement improved to 83%.

CONCLUSION

Visual analysis is useful in determining focal bone involvement, whereas semiquantitative analysis using SUVav/MBP has a high sensitivity and specificity for predicting BM involvement in patients lacking focal bone lesions.

The biodistribution of gold nanoparticles designed for renal clearance

Owing to their tunable optical properties and their high absorption cross-section of X- and γ-ray, gold nanostructures appear as promising agents for remotely controlled therapy. Since the efficiency of cancer therapy is not limited to the eradication of the tumour but rests also on the sparing of healthy tissue, a biodistribution study is required in order to determine whether the behaviour of the nanoparticles after intravenous injection is safe (no accumulation in healthy tissue, no uptake by phagocytic cell-rich organs (liver, spleen) and renal clearance). The biodistribution of Au@DTDTPA nanoparticles which are composed of a gold core and a DTDTPA (dithiolated polyaminocarboxylate) shell can be established by X-ray imaging (owing to the X-ray absorption of the gold core) and by magnetic resonance imaging (MRI) since the DTDTPA shell was designed for the immobilization of paramagnetic gadolinium ions. However scintigraphy appears better suited for a biodistribution study owing to a great sensitivity. The successful immobilization of radioelements ((99m)Tc, (111)In) in the DTDTPA shell, instead of gadolinium ions, renders possible the follow up of Au@DTDTPA by scintigraphy which showed that Au@DTDTPA nanoparticles exhibit a safe behaviour after intravenous injection to healthy rats.

Intrabone transplant of cord blood stem cells establishes a local engraftment store: a functional PET/FDG study

BACKGROUND

Despite advancements in comprehension of molecular mechanisms governing bone marrow (BM) homing of hematopoietic stem cells, cord blood transplant (CBT) suffers from a slow rate of hematopoietic recovery. Intrabone (i.b.) injection has been proposed as a method able to improve speed of BM engraftment with respect to conventional i.v. protocols. However, the mechanisms underlying this benefit are largely unknown.

AIM

To verify whether i.b.-CBT determines a local engraftment able to predict the reconstitution of recipient hematopoiesis.

DESIGN AND METHODS

Twenty-one patients with hematologic malignancies received i.b. injection into both iliac crests of 3.2 ± 0.68 ∗ 107/kg cord blood cells. One month following i.b.-CBT, PET-CT imaging was performed. Maximal standardized uptake values (SUVs) were assessed in BM of both iliac crests and in all lumbar vertebrae.

RESULTS

Maximal SUV within iliac crests was higher than in lumbar vertebrae (4.1 ± 1.7 versus 3.2 ± 0.7, resp., P = 0.01). However, metabolic activity in these two different BM districts was significantly correlated (r = 0.7, P < 0.001). Moreover, FDG uptake values within the injection site closely predicted platelet recovery 100 days after i.b.-CBT (r = 0.72, P < 0.01).

CONCLUSIONS

The metabolic activity of injected BM predicts the subsequent rate of hematopoietic recovery after i.b.-CBT, suggesting a pivotal role of the local engraftment in the reconstitution of recipient hematopoiesis.

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.