Active bone marrow segmentation based on computed tomography imaging in anal cancer patients: A machine-learning-based proof of concept

PURPOSE

Different methods are available to identify haematopoietically active bone marrow (ActBM). However, their use can be challenging for radiotherapy routine treatments, since they require specific equipment and dedicated time. A machine learning (ML) approach, based on radiomic features as inputs to three different classifiers, was applied to computed tomography (CT) images to identify haematopoietically active bone marrow in anal cancer patients.

METHODS

A total of 40 patients was assigned to the construction set (training set + test set). Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography (18FDG-PET) images were used to detect the active part of the pelvic bone marrow (ActPBM) and stored as ground-truth for three subregions: iliac, lower pelvis and lumbosacral bone marrow (ActIBM, ActLPBM, ActLSBM). Three parameters were used for the correspondence analyses between 18FDG-PET and ML classifiers: DICE index, Precision and Recall.

RESULTS

For the 40-patient cohort, median values [min; max] of the Dice index were 0.69 [0.20; 0.84], 0.76 [0.25; 0.89], and 0.36 [0.15; 0.67] for ActIBM, ActLSBM, and ActLPBM, respectively. The Precision/Recall (P/R) ratio median value for the ActLPBM structure was 0.59 [0.20; 1.84] (over segmentation), while for the other two subregions the P/R ratio median has values of 1.249 [0.43; 4.15] for ActIBM and 1.093 [0.24; 1.91] for ActLSBM (under segmentation).

CONCLUSION

A satisfactory degree of overlap compared to 18FDG-PET was found for 2 out of the 3 subregions within pelvic bones. Further optimization and generalization of the process is required before clinical implementation.

SFE-AFCE-SFMN 2022 Consensus on the management of thyroid nodules : What is the role of functional imaging and isotopic treatment?

The SFE-AFCE-SFMN 2022 consensus deals with the management of thyroid nodules, a condition that is a frequent reason for consultation in endocrinology. In more than 90% of cases, patients are euthyroid, with benign non-progressive nodules that do not warrant specific treatment. The clinician's objective is to detect malignant thyroid nodules at risk of recurrence and death, toxic nodules responsible for hyperthyroidism or compressive nodules warranting treatment. The diagnosis and treatment of thyroid nodules requires close collaboration between endocrinologists, nuclear medicine physicians and surgeons, but also involves other specialists. Therefore, this consensus statement was established jointly by 3 societies: the French Society of Endocrinology (SFE), French Association of Endocrine Surgery (AFCE) and French Society of Nuclear Medicine (SFMN); the various working groups included experts from other specialties (pathologists, radiologists, pediatricians, biologists, etc.). This section deals with the role of thyroid scintigraphy in the diagnosis of autonomous thyroid nodules, nuclear medicine in nodules with indeterminate cytology and iodine treatment for autonomous thyroid nodules.

"Aerobic glycolytic imaging" of human gliomas using combined pH-, oxygen-, and perfusion-weighted magnetic resonance imaging

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Aerobic glycolytic imaging combines pH-, oxygen-, and perfusion-weighted MRI.

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Aerobic glycolytic imaging depicts abnormal glucose metabolism of gliomas.

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IDH wild-type gliomas show higher aerobic glycolytic index compared with mutants.

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Aerobic glycolytic index in IDH wild-type glioma is correlated with glucose uptake.

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Aerobic glycolytic index in IDH mutant glioma is correlated to lactate transporters.

Purpose

To quantify abnormal metabolism of diffuse gliomas using “aerobic glycolytic imaging” and investigate its biological correlation.

Methods

All subjects underwent a pH-weighted amine chemical exchange saturation transfer spin-and-gradient-echo echoplanar imaging (CEST-SAGE-EPI) and dynamic susceptibility contrast perfusion MRI. Relative oxygen extraction fraction (rOEF) was estimated as the ratio of reversible transverse relaxation rate R₂′ to normalized relative cerebral blood volume. An aerobic glycolytic index (AGI) was derived by the ratio of pH-weighted image contrast (MTR_asym at 3.0 ppm) to rOEF. AGI was compared between different tumor types (N = 51, 30 IDH mutant and 21 IDH wild type). Metabolic MR parameters were correlated with ¹⁸F-FDG uptake (N = 8, IDH wild-type glioblastoma), expression of key glycolytic proteins using immunohistochemistry (N = 38 samples, 21 from IDH mutant and 17 from IDH wild type), and bioenergetics analysis on purified tumor cells (N = 7, IDH wild-type high grade).

Results

AGI was significantly lower in IDH mutant than wild-type gliomas (0.48 ± 0.48 vs. 0.70 ± 0.48; P = 0.03). AGI was strongly correlated with ¹⁸F-FDG uptake both in non-enhancing tumor (Spearman, ρ = 0.81; P = 0.01) and enhancing tumor (ρ = 0.81; P = 0.01). AGI was significantly correlated with glucose transporter 3 (ρ = 0.71; P = 0.004) and hexokinase 2 (ρ = 0.73; P = 0.003) in IDH wild-type glioma, and monocarboxylate transporter 1 (ρ = 0.59; P = 0.009) in IDH mutant glioma. Additionally, a significant correlation was found between AGI derived from bioenergetics analysis and that estimated from MRI (ρ = 0.79; P = 0.04).

Conclusion

AGI derived from molecular MRI was correlated with glucose uptake (¹⁸F-FDG and glucose transporter 3/hexokinase 2) and cellular AGI in IDH wild-type gliomas, whereas AGI in IDH mutant gliomas appeared associated with monocarboxylate transporter density.

Characterization of metabolic activity induced by kainic acid in adult rat whole brain at the early stage: A 18FDG-PET study

OBJECTIVE

Brain metabolic processes are not fully characterized in the kainic acid (KA)-induced Status Epilepticus (KASE). Thus, we evaluated the usefulness of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) as an experimental strategy to evaluate in vivo, in a non-invasive way, the glucose consumption in several brain regions, in a semi-quantitative study to compare and to correlate with data from electroencephalography and histology studies.

METHODS

Sixteen male Wistar rats underwent FDG-PET scans at basal state and after KA injection. FDG-PET images were normalized to an MRI-based atlas and segmented to locate regions. Standardized uptake values (SUV) were obtained at several time points. EEGs and cell viability by histological analysis, were also evaluated.

RESULTS

FDG-PET data showed changes in regions such as: amygdala, hippocampus, accumbens, entorhinal cortex, motor cortex and hypothalamus. Remarkably, hippocampal hypermetabolism was found (mean SUV = 2.66 ± 0.057) 2 h after KA administration, while hypometabolism at 24 h (mean SUV = 1.83 ± 0.056) vs basal values (mean SUV = 2.19 ± 0.057). EEG showed increased spectral power values 2 h post-KA administration. Hippocampal viable-cell counting 24 h after KA was decreased, while Fluoro-Jade B-positive cells were increased, as compared to control rats, coinciding with the hypometabolism detected in the same region by semi-quantitative FDG-PET at 24 h after KASE.

CONCLUSIONS

PET is suitable to measure metabolic brain changes in the rat model of status epilepticus induced by KA (KASE) at the first 24 h, compared to that of EEG; PET data may also be sensitive to cell viability.

Pulmonary nodules in patients with primary Sjögren's syndrome: Causes, clinico-radiologic features, and outcomes

BACKGROUND

Primary Sjögren's Syndrome (pSS) is characterized by an immune-mediated lymphoplasmacytic infiltration of the salivary and lacrimal glands. Pulmonary nodules are not uncommonly encountered in these patients.

METHODS

We conducted a retrospective computer-assisted search for patients with pSS who were encountered at our institution between 1999 and 2018 and had histologically characterized pulmonary nodule(s)/mass (es) (PNs).

RESULTS

Of 41 patients with pSS and PNs, median age was 67 years (IQR, 56-74), 94% were women, and 39% had a smoking history. The PNs proved to be non-Hodgkin lymphoma (NHL) in 16 patients (39%), lung carcinoma in 11 patients (27%), other malignancies in 2 patients (5%), and benign diseases in remaining 12 patients (29%), including 7 with amyloidomas. Patients with NHL were younger (p = 0.006) while smoking exposure was more prevalent in patients with lung carcinoma (p = 0.022). Patients with NHL had a higher number of PNs and more often manifested random distribution, cysts, ground-glass changes and consolidations. Upper and/or mid-lung location, spiculated borders, solitary nodule, increasing size, and higher SUV_mean on FDG-PET scan were associated with lung carcinoma. At the end of follow-up (median 5.9 years), 8 patients (20%) had died and included 5 patients with lung carcinoma; no deaths were observed in the NHL group.

CONCLUSIONS

The majority of biopsied PNs in patients with pSS were malignant, most commonly lymphomas. Smoking exposure, solitary nodule, and high FDG avidity were more frequently associated with lung carcinoma. The clinical context, CT and ¹⁸FDG-PET are complementary in the evaluation and management of PNs in patients with pSS.

Evaluation of decreased uptake of 18F-fluorodeoxyglucose in the cerebral cortex of patients with intracranial non-Hodgkin's lymphoma lesions through PET/CT

BACKGROUND

This study aims to investigate whether basal ganglia can be utilised as reference for measuring ratios between standardised uptake values (SUV), namely, SUV_max and SUV_mean, of 18F-fluoro-deoxyglucose (18F-FDG) uptake, in the ipsilateral cerebral cortex and basal ganglia of patients with non-Hodgkin's lymphoma lesions.

METHODS

Fifty-three patients with pathologically confirmed highly metabolic non-Hodgkin's lymphoma were retrospectively analysed; these patients were subjected to treatment strategy and underwent positron emission tomography/computed tomography (PET/CT). Nineteen of the patients who improved after the treatment were re-examined by PET/CT. PET/CT simultaneity was performed on 12 normal volunteers as the control group. SUV_max and SUV_mean in the cerebral cortex and basal ganglia (head of caudate nucleus and lenticular nucleus) were evaluated by ganglia was also calculated. The ratios were compared between patients and the control group as well as before and after the treatment.

RESULTS

The ratios between the SUV_max of 18F-FDG uptake were 1.03±0.16 (range 0.50-1.51, left) in the ipsilateral cerebral cortex and 1.02±0.16 (range 0.50-1.31, right) in the basal ganglia of 53 patients with non-Hodgkin's lymphoma; the corresponding ratios in the 12 controls were 1.09±0.11 (range 0.99-1.21, left) and 1.09±0.09 (range 1.00-1.24, right), respectively. The ratios between the SUV_mean and 18F-FDG uptake in the ipsolateral cerebral cortex and basal ganglia were 0.76±0.09 (range 0.50-1.07, left) and 0.76±0.09 (range 0.48-0.98, right), respectively, which were lower than those in the control group [0.93±0.06 (range 0.83-0.99, left) and 0.92±0.05 (range 0.84-0.99, right), respectively]. For patients effectively treated, the ratios between the SUV_max in the ipsolateral cerebral cortex and basal ganglia were 1.08±0.13 (range 0.94-1.36, left) and 1.08±0.13 (range 0.88-1.31, right) before the treatment; these values were similar to 1.11±0.13 (range 0.85-1.36, left) and 1.09±0.11 (range 0.90-1.32, right) obtained in the ipsolateral cerebral cortex and basal ganglia of the patients after the treatment, respectively. The ratios between the SUV_mean in the ipsolateral cerebral cortex and basal ganglia were 0.78±0.06 (range 0.68-0.93, left) and 0.78±0.06 (range 0.69-0.95, right) in the patients before the treatment; these ratios were lower than those in post-treatment patients [0.90±0.06 (range 0.74-1.00, left) and 0.90±0.07 (range 0.72-1.00, right), respectively], respectively.

CONCLUSION

High levels of 18F-FDG metabolism in patients with non-Hodgkin's lymphoma may decrease glucose uptake in the cerebral cortex (diversion of 18F-FDG from the cerebral tissue to the lymphoma tissue); this phenomenon may be reversed with effective therapy for lymphoma. The ratio with 18F-FDG metabolism in basal ganglia could be used as reference to quantify and monitor glucose metabolism in cerebral tissues during the course of lymphoma.

A serial ¹⁸FDG-PET study of a patient with SSPE who had good prognosis by combination therapy with interferon alpha and ribavirin

We describe a 15-year-old girl with subacute sclerosing panencephalitis (SSPE) in stage II who was treated with isoprinosine, intraventricular interferon alpha (IFN-α), and ribavirin for 3 years. She is alive at three years from onset and studies at school with the assistance of a special educational teacher. To assess residual brain function, serial (18)FDG-positron emission tomography (PET) was performed three times to measure cortical metabolism: at onset, a year later, and three years later. At onset, PET study revealed preserved glucose metabolism of the cerebral cortex. In serial PET study, glucose metabolism of the cerebral cortex was also preserved even after three years. Although SSPE is a progressive disease of the neuronal system, and typically leads to death in approximately 2-3 years, the neurological prognosis of our case was good. We consider that combination therapy in the very early stage without hypometabolism in the cerebral cortex may be effective for SSPE.

Measurement of brown adipose tissue mass using a novel dual-echo magnetic resonance imaging approach: a validation study

OBJECTIVE

The aim of this study was to evaluate and validate magnetic resonance imaging (MRI) for the visualization and quantification of brown adipose tissue (BAT) in vivo in a rat model. We hypothesized that, based on differences in tissue water and lipid content, MRI could reliably differentiate between BAT and white adipose tissue (WAT) and could therefore be a possible alternative for (18)F-Fluorodeoxyglucose Positron Emission Tomography ((18)FDG-PET), the current gold standard for non-invasive BAT quantification.

MATERIALS/METHODS

Eleven rats were studied using both (18)FDG-PET/CT and MRI (1.5 T). A dual echo (in-and-out-of-phase) sequence was used, both with and without spectral presaturation inversion recovery (SPIR) fat suppression (DUAL-SPIR) to visualize BAT, after which all BAT was surgically excised. The BAT volume measurements obtained via (18)FDG-PET/CT and DUAL-SPIR MR were quantitatively compared with the histological findings. All study protocols were reviewed and approved by the local ethics committee.

RESULTS

The BAT mass measurements that were obtained using DUAL-SPIR MR subtraction images correlated better with the histological findings (P=0.017, R=0.89) than did the measurements obtained using (18)FDG-PET/CT (P=0.78, R=0.15), regardless of the BAT metabolic activation state. Additionally, the basic feasibility of the DUAL-SPIR method was demonstrated in three human pilot subjects.

CONCLUSIONS

This study demonstrates the potential for MRI to reliably detect and quantify BAT in vivo. MRI can provide information beyond that provided by (18)FDG-PET imaging, and its ability to detect BAT is independent of its metabolic activation state. Additionally, MRI is a low-cost alternative that does not require radiation.