Implementation of xSPECT, xSPECT bone and Broadquant from literature, clinical survey and innovative phantom study with task-based image quality assessment.

OBJECTIVE: From patient and phantom studies, we aimed to highlight an original implementation process and share a two-years experience clinical feedback on xSPECT (xS), xSPECT Bone (xB) and Broadquant quantification (Siemens) for 99mTc-bone and 177Lu-NET (neuroendocrine tumors) imaging. METHODS: Firstly, we checked the relevance of implemented protocols and Broadquant module on the basis of literature and with a homogeneous phantom study respectively. Then, we described xS and xB behaviours with reconstruction parameters (10i-0mm to 40i-20mm) and optimized the protocols through a blinded survey (7 physicians). Finally, the preferred 99mTc-bone reconstruction was assessed through an IEC NEMA phantom including liquid bone spheres. Conventional SNR, CNR, spatial resolution, Q.%error, and recovery curves; and innovative NPS, TTF and detectability score d' were performed (ImQuest software). We also sought to review the adoption of these tools in clinical routine and showed the potential of quantitative xB in the context of theranostics (Xofigo®). RESULTS: We showed the need of optimization of implemented reconstruction algorithms and pointed out a decay correction particularity with Broadquant. Preferred parameters were 1s-25i-8mm and 1s-25i-5mm for xS/xB-bone and xS-NET imaging respectively. The phantom study highlighted the different image quality especially for the enhanced spatial resolution xB algorithm (1/TTF10%=2.1 mm) and showed F3D and xB shared the best performances in terms of image quality and quantification. xS was generally less efficient. CONCLUSIONS: Qualitative F3D still remains the clinical standard, xB and Broadquant offer challenging perspectives in theranostics. We introduced the potential of innovative metrics for image quality analysis and showed how CT tools should be adapted to fit nuclear medicine imaging.

Predicting subacute hematological toxicity of 177Lu-DOTATATE therapy using healthy organs' uptake on post-treatment quantitative SPECT: A pilot study.

The aim is to investigate the usefulness of 177Lu-DOTA-0-Tyr3-Octreotate (DOTATATE) healthy organs' (spleen, kidneys, bone marrow) standard uptake value for the prediction of subacute hematological toxicity in patients undergoing 177Lu-DOTATATE treatment. All patients referred from January 2021 to May 2022 for 177Lu-DOTATATE treatment were retrospectively screened. For each treatment session, baseline clinical data including age, sex, weight, delay between 177Lu-DOTATATE treatment and last cold somatostatin analogue intake were collected. Mean standardized uptake value (SUVmean) of healthy organs was measured and analyzed by generalized linear mixed effect models. Outcomes (significant decrease of platelets, hemoglobin levels and neutrophils) were assessed 1 month later, considering their within-subject biological coefficient of variation, published by the European Federation of Clinical Chemistry and Laboratory Medicine. A total of 9 patients (33 treatment sessions) were included. No predictive factors were identified for platelet and neutrophil decrease. Splenic SUVmean was found to be a significant predictor of hemoglobin levels decrease. Using an optimal threshold of ≥6.22, derived sensitivity and specificity to predict hemoglobin decrease were 85.7% [46.4; 99.0] and 76.9% [57.5; 89.2] respectively with an accuracy of 82.4%. Although not significantly predictive of hematological toxicity, bone marrow SUVmean and renal SUVmean were correlated with splenic SUVmean. Quantitative single photon emission computed tomography and healthy organs analysis might help to foresee hematological subacute toxicity in patients undergoing 177Lu-DOTATATE treatment and improve patient management.

Gonadotropin-Secreting Pituitary Macroadenoma Complicated With Hemorrhagic Apoplexy in 18F-FDG PET/CT.

ABSTRACT: We report the case of 69-year-old man referred for a stage IV pulmonary adenocarcinoma and presenting a decrease in visual acuity. An 18F-FDG PET/CT showed an intense and heterogeneous uptake of a mass in the sellar region. An MRI showed a pituitary macroadenoma associated with a large cyst on the left side, with necrosis zones and fluid level, compressing the optic chiasma. Endocrine testing showed a panhypopituitarism, and pathology confirmed a pituitary apoplexy in a gonadotropin-secreting macroadenoma. No malignant cells were detected. Molecular imaging could have an important role in the detection and characterization of pituitary tumors.

18F-FDG PET/CT in Anti-Leucine-Rich Glioma-Inactivated 1 Antibody Encephalitis: Typical Pattern and Follow-up.

ABSTRACT: We report the case of a 55-year-old man presenting pseudopsychiatric behavior disorders of subacute-onset. MRI showed a FLAIR (fluid-attenuated inversion recovery) hyperintensity in the left hippocampus. The diagnosis of limbic encephalitis was raised, and the patient was referred for an 18F-FDG PET/CT. PET/CT depicted an increased uptake of the left mesiotemporal structures and also an increased uptake of both cerebellum and striatal areas. This pattern was compatible with an anti-leucine-rich glioma-inactivated 1 antibody encephalitis that was later confirmed.

Multimodality Imaging Features of a Misleading Sacral Giant Cell Tumor in 18F-FDG PET/CT, Bone Scan, and MRI.

We report the case of an asymptomatic 66-year-old woman referred for initial staging of an invasive ductal breast carcinoma. Initial workup incidentally revealed a bone tumor of right sacral wing corresponding to a giant cell tumor (GCT). We present the imaging characteristics of GCT on Tc-HDP bone scan (doughnut sign), F-FDG PET/CT (intense and heterogeneous uptake of a prominent geographic lytic lesion with partial rupture of cortical), and MRI (hyposignal with gadolinium enhancement on T1-weighted images and heterogeneous hypersignal on T2-weighted images). GCT is a benign but locally aggressive primary bone tumor, constituting a pitfall and diagnostic challenge.

18F-FDG PET/CT in Sporadic Creutzfeldt-Jakob Disease.

We report the case of a 64-year-old man referred for optic ataxia, constructional apraxia, and spatial orientation disorders evolving for 2 months. Benson syndrome (posterior cortical atrophy) was initially suspected. Brain F-FDG PET/CT depicted an asymmetric decreased uptake pattern consistent with Creutzfeldt-Jakob disease. 14-3-3 proteins were detected in the cerebrospinal fluid. Clinical evolution was quickly unfavorable. The patient died 1 month after the PET/CT, and Creutzfeldt-Jakob disease was confirmed on postmortem examination of brain tissue.

18FDG PET/CT in Primary Cutaneous Diffuse Large B-Cell Lymphoma Leg Type.

An 86-year-old woman was referred for a rare but aggressive subtype of primary cutaneous lymphoma of the right lower limb: diffuse large B-cell lymphoma leg type. Initial evaluation by whole-body F-FDG PET/CT showed intense hypermetabolic activity of multiple cutaneous and subcutaneous nodules of the distal third of the right leg. Follow-up evaluations by F-FDG PET/CT showed complete response after 4 and 8 cycles of appropriate rituximab combination with polychemotherapy. Although no specific recommendations are available, our case stresses the major role of F-FDG PET/CT for initial extension and treatment response evaluation in clinical practice of primary cutaneous diffuse large B-cell lymphoma leg type.

PET/CT of Duodenal Gangliocytic Paraganglioma.

An 87-year-old woman with leg-type lymphoma underwent a staging F-FDG PET/CT, which demonstrated besides leg lymphomatous lesions a round, well-defined, preduodenal mass with moderate FDG uptake. This mass remained unchanged after chemotherapy treatment completion, despite a complete metabolic response of lymphomatous lesions. A biopsy revealed a gangliocytic paraganglioma. Subsequent F-FDOPA PET/CT and somatostatin receptor scintigraphy were positive and did not depict any other lesions.

18F-FDG PET/CT Evaluation of Crizotinib and Lorlatinib Therapy in Metastatic ROS-1-Positive Non-Small Cell Lung Cancer.

ROS-1-positive non-small cell lung cancers (NSCLCs) are rare (approximately 1% of all NSCLCs) and require a first-line treatment by crizotinib. Crizotinib resistance is frequent within the first 12 months of treatment. Lorlatinib is a novel tyrosine kinase inhibitor of ROS-1 recently indicated for metastatic or locally advanced crizotinib-resistant NSCLC. We report the use of lorlatinib as second-line with a complete tumoral response after only 3 months of treatment. This case shows the major role of F-FDG PET/CT in treatment evaluation and monitoring targeted therapy in metastatic NSCLC.

Added value of 18F-fluorocholine positron emission tomography-computed tomography in presurgical localization of hyperfunctioning parathyroid glands after dual tracer subtraction scintigraphy failure: A retrospective study of 47 patients.

Hyperparathyroidism is a common endocrine disorder. The precise localization of causal parathyroid gland is crucial to guide surgical treatment. Several studies report the added value of 18F-fluorocholine (FCH) positron emission tomography-computed tomography (PET/CT) as second line imaging but rely on suboptimal first-line imaging using 99mTc-sestaMIBI dual phase scintigraphy. The aim of this study is to evaluate the percentage of successful parathyroid localization with FCH PET/CT after failure of a more sensitive first-line detection protocol associating neck ultrasonography and 99mTc-Pertechnetate/99mTc-sestaMIBI dual tracer subtraction scintigraphy.We included retrospectively 47 patients who underwent a FCH PET/CT as second line imaging for biologically proven primary hyperparathyroidism from November 2016 to October 2018 in Godinot Institute (Reims, France). 99mTc-Pertechnetate/99mTc-sestaMIBI dual tracer subtraction scintigraphy and neck ultrasonography were used as first-line imaging and failed to localize the causal parathyroid lesion in all cases.FCH PET/CT demonstrated at least 1 parathyroid target lesion in 29 patients (62%). 21/29 patients underwent surgery. Target lesions corresponded histologically to hyperfunctioning parathyroid glands for all 21 patients and surgery was followed by hyperparathyroidism biological resolution. Calcium serum levels were associated to FCH PET/CT positivity (P = .002) and a trend toward significance was seen for Parathyroid hormone (PTH) levels (P = .09).FCH PET/CT is a promising tool in second-line parathyroid imaging. Large prospective studies and cost-effectiveness analyses are needed to precise its role.

18F-FDG PET/CT in Oral Cuniculatum Carcinoma.

A 69-year-old woman was referred for initial staging of an oral cavity mass. F-FDG PET/CT displayed a homogeneous intense uptake of the 50-mm left hemipalatal mass with local extension to the dental arcade and maxillary sinus. Infracentimetric bilateral cervical nodes with faint uptake were also detected, contrasting with the usual presentation of other head and neck squamous cell carcinoma. Biopsy concluded to a rare head and neck squamous cell carcinoma subtype: oral cuniculatum carcinoma (OCC). After radiotherapy, 18F-FDG PET/CT showed metabolic complete response. Our case describing specifically the metabolic characteristics of OCC and radiotherapy evaluation for this rare tumor.

Everolimus-induced pulmonary toxicity: Findings on 18F-FDG PET/CT imaging.

The everolimus-exemestane combination is indicated in advanced breast cancer treatment and usually well tolerated. The objective of the study was to determine the frequency of everolimus lung side effects and investigate their imaging characteristics on positron emission tomography with 18F-fluoro-deoxy-glucose combined with computerized tomography (F-FDG PET/CT).Our single-center retrospective descriptive study systematically included all patients with metastatic breast cancer treated by this combination (n = 29 representing 57 F-FDG PET/CT). Number of segments involved was quantified. Maximum standardized uptake value (SUVmax), average standardized uptake value (SUVmean), metabolic target volume (MTV), and total lesion glycolysis (TLG) were measured. Severe pneumopathy was studied by subgroup analysis.Pleuroparenchymal anomalies rate detected on F-FDG PET/CT was 62%. Alveolar-interstitial lesions were mainly observed (89%) and affected 2.8 segments (0.5-11.5) with a median of 2 segments. S7 and S10 were the most involved segments with SUVmax 3.9 (1.3-8.8) and SUVmean 2.2 (0.7-4.9). Statistically significant difference (P = .02) was found with number of segment involved to characterize severe pneumopathy (average of 6.3 segments [2.5-11.5] vs 1.9 segments [0.5-8] for interstitial lung disease) but not with SUVmax, SUVmean, MTV, TLG (P = .14, 0.22, 0.22, and 0.17, respectively).The F-FDG PET/CT could highlight pulmonary everolimus side effects, with a typical imaging pattern: alveolar-interstitial opacities associated with moderate uptake, more or less extensive, mainly affecting the lower lobes. Rarely, a pseudotumoral aspect may be detected, corresponding to a pitfall. MTV or TLG showed a tendency to differentiate severe pneumopathy vs interstitial lung disease but no statistically significant differences was observed contrarily to the number of segments involved. Further studies are necessary to determine if the F-FDG PET/CT could early predict adverse effects of mTOR inhibitors.

Hepatic Metastases From Prostatic Adenocarcinoma Without Elevated 18F-Choline Activity.

We report the case of a 69-year-old man referred for F-fluorocholine (FCH) PET/CT for a biochemical recurrence of prostate cancer. FCH PET/CT demonstrated 2 hypodense hepatic lesions with no uptake but progressing in size compared with a previous assessment. MRI showed a suspicious peripheral contrast enhancement, raising the question of a liver metastasis. Histopathologic examination concluded to a prostate adenocarcinoma metastasis. This case highlights an unusual pitfall in FCH PET/CT: the lack of uptake in prostatic liver metastasis is presumably due to the partial volume effect induced by the necrotic center and the high uptake of the liver.

18F-FDG PET/CT in Anti-NMDA Receptor Encephalitis: Typical Pattern and Follow-up.

We report the case of a 28-year-old woman presenting behavior disorders of subacute onset. She was referred in our institution for a suspicion of limbic encephalitis. F-FDG PET/CT did not show any mesiotemporal abnormality but depicted a decreased uptake of bilateral parietal and occipital lobes. This atypical pattern was compatible with an anti-N-methyl-D-aspartate receptor encephalitis that was later confirmed.

Periurethral Mass Mimicking Neoplasm After Injection of Macroplastique for Postprostatectomy Stress Incontinence: A Pitfall on 18F-FDG PET/CT.

A 64-year-old man underwent initial F-FDG PET/CT staging for gastric cardia adenocarcinoma, which showed the primary gastric tumor, several bone metastases, and high uptake in a periurethral mass mimicking pelvic neoplasm developed after injection of polydimethylsiloxane (Macroplastique) urethral bulking agent 6 years ago for postprostatectomy stress urinary incontinence. This case showed a very rare complication of silicon particle injection therapy, and the intense uptake is likely due to granulomatous reaction around the implant.

Infection of Ventricular Assist Device Detected and Monitored by 18F-FDG PET/CT.

We report a case of a 59-year-old man who presented with fever, sepsis, and left cervicothoracic cutaneous inflammation 13 months after implantation of Jarvik 2000 device. Device infection was suspected and F-FDG PET/CT showed an intense and homogeneous uptake along driveline cable. Bacteriological local sample showed Staphylococcus aureus. After adapted antibiotherapy, control F-FDG PET/CT displays treatment efficacy with no residual uptake in driveline. F-FDG PET/CT could be an important tool for early noninvasive detection of left ventricular assist device infection and monitoring antibiotherapy response.

18F-FDG PET/CT Evaluation of Ceritinib Therapy in Metastatic ALK-Positive Non-small Cell Lung Cancer.

Anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancers (NSCLC) account for 3% to 7% of all NSCLC and require a standard treatment by crizotinib. However, crizotinib resistance is frequent within the first 12 months of treatment. Ceritinib is a novel tyrosine kinase inhibitor of ALK recently introduced in France for metastatic or locally advanced crizotinib-resistant ALK NSCLC. We report the first use of ceritinib in our institution with a spectacular tumoral response after only 3 months of treatment. This case demonstrates the major role of F-FDG PET/CT for monitoring the effectiveness of this new treatment.