Qualitative and Quantitative Evaluation of Morpho-Metabolic Changes in Bone Cartilage Complex of Knee Joint in Osteoarthritis Using Simultaneous 18F-NaF PET/MRI-A Pilot Study.

Background Articular cartilage (AC) loss and deterioration, as well as bone remodeling, are all symptoms of osteoarthritis (OA). As a result, an ideal imaging technique for researching OA is required, which must be sensitive to both soft tissue and bone health. Objective The aim of this study was to assess the potential of simultaneous 18F sodium fluoride (18F-NaF) positron emission tomography/magnetic resonance imaging (PET/MRI) to identify as well as classify osseous metabolic abnormalities in knee OA and to see if degenerative changes in the cartilage and bone on MRI might be correlated with subchondral 18F-NaF uptake on PET. Methods Sixteen (32 knees) volunteers with no past history of knee injury, with or without pain, were enrolled for the research from January to July 2021. The images of both knees were taken utilizing an molecular magnetic resonance (mMR) body matrix coil on a simultaneous PET/MRI biograph mMR. The acquisition was conducted after 45 minutes of intravenous infusion of 18F-NaF 185-370 MBq (5-10 mCi) over one PET bed for 40 minutes, while MRI sequences were performed simultaneously. Results All pathologies showed significantly higher maximum standardized uptake value (SUV max ) than the background. Thirty-four subchondral magic spots were identified on 18F-NaF PET without any structural alteration on MRI. Bone marrow lesions (BMLs) and osteophytes with higher MRI osteoarthritis knee score (MOAKS) score showed higher 18F-NaF uptake (grade1˂grade2˂grade3). BMLs had corresponding AC degeneration. There was discordance between grade 1 osteophytes (86.6%), sclerosis (53.7%) and grade 1 BML in cruciate ligament insertion site (91.66%); they did not have high uptake of 18F-NaF. In case of cartilage, there was significant difference between AC grades and average subchondral SUV max and T2* relaxometry (grade0˂grade1˂grade2˂grade3˂grade4). BMLs are much more metabolically active than other pathologies, while sclerosis is the least. We also found that the subchondral uptake was statistically increased in the areas of pathology: Conclusion 18F-NaF PET/MRI was able to detect knee abnormalities unseen on MRI alone and simultaneously assessed metabolic and structural markers of knee OA across multiple tissues in the joint. Thus, it is a promising tool for detection of early metabolic changes in OA.

Recurrent Glioma: Does Qualitative Simultaneous 18F-DOPA PET/mp-MRI Improve Diagnostic Workup? An Initial Experience.

RATIONALE OF THE STUDY: Neuroimaging modalities such as contrast-enhanced MRI and PET provide significant insight in the evaluation of gliomas. However, their reliability in successfully differentiating the tumor recurrence with treatment-related changes is still technologically challenging. The current study aims to qualitatively investigate the potential of the hybrid PET/multiparametric MRI modality to noninvasively distinguish between these 2 outcomes of brain tumor diagnostics for optimum and early patient management. PATIENTS AND METHODS: A cohort of 26 suspected recurrent glioma cases proved on histology and/or clinicoradiological outcome forms the part of this study. A 3-point visual analytical scale was used to qualify lesions as recurrent or posttreatment radiation effects on PET, conventional MRI, dynamic susceptibility contrast-perfusion-weighted imaging, apparent diffusion coefficient, and the MR spectroscopy according to their level of suspicion. RESULTS: Of the 26 patients, 21 patients were classified as recurrence and 5 as radiation necrosis. Advanced MRI parameters (perfusion, diffusion, and spectroscopy) integrated with 18F-DOPA PET imaging resulted in superior diagnostic performance obtained on visual assessment with an accuracy of 95%, sensitivity of 96%, and specificity approaching up to 100% over individual modalities. CONCLUSIONS: The combination of multiple MR parameters evaluated together with 18F-DOPA PET offers an attractive approach to noninvasively distinguish true recurrence from radiation necrosis. However, further prospective studies with larger cohorts are warranted with additional neuropathological validations.

Emerging role of integrated PET-MRI in osteoarthritis.

Osteoarthritis (OA) is a common degenerative disorder of the articular cartilage, which is associated with hypertrophic changes in the bone, synovial inflammation, subchondral sclerosis, and joint space narrowing (JSN). Radiography remains the first line of imaging till now. Due to the lack of soft-tissue depiction in radiography, researchers are exploring various imaging techniques to detect OA at an early stage and understand its pathophysiology to restrict its progression and discover disease-modifying agents in OA. As the OA relates to the degradation of articular cartilage and remodeling of the underlying bone, an optimal imaging tool must be sensitive to the bone and soft tissue health. In that line, many non-invasive imaging and minimally invasive techniques have been explored. Out of these, the non-invasive compositional magnetic resonance imaging (MRI) for evaluation of the integrity of articular cartilage and positron emission tomography (PET) scan with fluorodeoxyglucose (FDG) and more specific bone-seeking tracer like sodium fluoride (18F-NaF) for bone cartilage interface are some of the leading areas of ongoing work. Integrated PET-MRI system, a new hybrid modality that combines the virtues of the above two individual modalities, allows detailed imaging of the entire joint, including soft tissue cartilage and bone, and holds great potential to research complex disease processes of OA. This narrative review attempts to signify individual characteristics of MRI, PET, the fusion of these characteristics in PET-MRI, and the ongoing research on PET-MRI as a potential tool to understand the pathophysiology of OA.

A Practical Approach to Optimize Scan Protocol for Simultaneous Whole-Body Positron Emission Tomography/Magnetic Resonance Imaging in Cancer Staging.

OBJECTIVE: The aim of the report is to present time efficient whole-body positron emission tomography/magnetic resonance imaging (PET/MRI) protocol evolved and tested for comprehensive evaluation of cancer patients. MATERIALS AND METHODS: Whole body as well as regional simultaneous PET and MRI was performed on Biograph mMR (Siemens, Erlangen, Germany) Simultaneous PET/MRI system in 4500 clinical cases of various cancers from 2013 to 2017 with an in-house designed imaging protocol to assess its utility. RESULTS: Using this protocol, the whole body is covered with optimized sequences (T1, T2, short tau inversion recovery, diffusion, and 3D volumetric interpolated breath-held) with PET which has been found adequate for complete metastatic workup in 30-45 min. With region-specific studies, it provides a comprehensive staging workup in an additional 10-15 min. The workflow offered additive advantages of effectively addressing incidentalomas besides being useful in terms of diagnostic utility. CONCLUSION: The proposed whole-body PET MRI imaging protocol used in a clinical setting is found acceptable and reasonably time efficient to optimally exploit the potentials of the technique in oncology.

Improving Diagnosis of Primary Prostate Cancer With Combined 68Ga-Prostate-Specific Membrane Antigen-HBED-CC Simultaneous PET and Multiparametric MRI and Clinical Parameters.

OBJECTIVE: The current study was designed to test the diagnostic performance of 68Ga-prostate-specific membrane antigen (PSMA) PET and multiparametric MRI along with clinical parameters in the characterization of prostatic lesions. MATERIALS AND METHODS: Eighty-two men with 63 malignant and 21 benign histologically proven prostate lesions who underwent complete clinical workup were included in this retrospective study. All patients underwent simultaneous whole-body 68Ga-PSMA PET/MRI with dedicated multiparametric MRI. Prostate Imaging-Reporting and Data System (PI-RADS) version 2 assessment was used for predicting the likelihood of cancer. Uptake of 68Ga-PSMA was recorded by adopting the copy-and-paste function of ROIs defined on MR images. ROC and combined ROC analyses were performed to test the diagnostic accuracy of individual and combined parameters. Spearman analysis was used to assess the correlations. RESULTS: PSMA uptake (maximum standardized uptake value) was significantly different among tumors with Gleason scores of 7, 8, and 9, with the lowest uptake in tumors with a score of 7 and the highest uptake in tumors with a score of 9. There was a significant difference between early- and delayed-phase PSMA uptake in malignant prostatic lesions (p < 0.01). Significant correlations were observed between delayed and differential PSMA uptake and PI-RADS category (p < 0.01 and < 0.01, respectively), digital rectal examination findings (p = 0.01 and < 0.01, respectively), Gleason score (p = 0.05 and < 0.05, respectively), and prostate-specific antigen levels (p = 0.01 for both). Combined ROC analysis of prostate-specific antigen levels, digital rectal examination findings, multiparametric MRI, and differential PSMA uptake were able to characterize prostatic lesions with a mean (± SD) AUC of 0.94 ± 0.03, compared with their individual AUCs of 0.77, 0.70, 0.82, and 0.88. CONCLUSION: Gallium-68-PSMA PET combined with multiparametric MRI showed high diagnostic accuracy for prostate cancer diagnosis compared with either multiparametric MRI or PET alone or with clinical factors (e.g., digital rectal examination or prostate-specific antigen level) alone, and the combination further improves characterization of prostatic lesions.

Simultaneous 18F- FDG PET/MRI in Autoimmune Limbic Encephalitis.

Limbic encephalitis is an autoimmune disorder characterized by inflammation of the brain with rapidly progressing dementia which requires definitive neurological evaluation. We describe both clinical as well as imaging findings in a case of limbic encephalitis using positron emission tomography/magnetic resonance imaging.

Effect of Combined 68Ga-PSMAHBED-CC Uptake Pattern and Multiparametric MRI Derived With Simultaneous PET/MRI in the Diagnosis of Primary Prostate Cancer: Initial Experience.

OBJECTIVE: The purpose of this study is to assess whether temporal changes in 68Ga-prostate-specific membrane antigen (PSMA)-HBED-CC uptake and multiparametric MRI parameters derived using PET/MRI can aid in characterization of benign and malignant prostate lesions. MATERIALS AND METHODS: Thirty-five men with 29 malignant and six benign prostate lesions undergoing complete clinical workup including histologic analysis were enrolled for this retrospective study. All had undergone simultaneous whole-body 68Ga-PSMAHBED-CC PET/MRI. Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) assessment was made using a 5-point scale showing the likelihood of cancer with the combination of multiparametric MRI findings. Gallium-68-PSMA uptake was recorded at two time points: early (7 minutes) and delayed (54 minutes), adopting a copy-and-paste function of the ROI defined on MR images. ROC curve analysis was performed to test the diagnostic accuracy of early versus delayed PSMA uptake (measured as maximum standardized uptake value [SUV]). A multiple-ROI analysis was done to obtain ROCs for combined PET SUV and multiparametric MRI datasets. Spearman analysis was performed to assess the correlations. RESULTS: There was a significant difference between early and delayed PSMA uptake in malignant prostatic lesions (p < 0.01), which was able to characterize prostate lesions with an AUC of 0.83 and 0.94. Combined ROC analysis of PI-RADSv2 category derived from multiparametric MRI and differential PSMA uptake in characterizing prostatic lesions improved the AUC to 0.99. CONCLUSION: Dual-phase PSMA uptake improves accuracy of classifying malignant versus benign prostate lesions and complements multiparametric MRI in the diagnosis of prostate cancer.

68Ga-Prostate-Specific Membrane Antigen-Avid Tubercular Lesions Mimicking Prostate Cancer Metastasis on Simultaneous Prostate-Specific Membrane Antigen PET/MRI.

Ga-prostate-specific membrane antigen (PSMA) has gained increasing interest as a target molecule in imaging of prostate cancer because of its selective overexpression in local prostate cancer lesions and metastasis. We report a case of a 62-year-old man with raised serum prostate-specific antigen levels who presented for Ga-PSMA HBED-CC simultaneous PET/MRI for prostate cancer evaluation. A PSMA-nonavid PI-RADS 5 (Prostate Imaging-Reporting and Data System) lesion was confirmed as adenocarcinoma on histopathology. The PSMA-avid lesions were noted in the calvarium and lung, with the calvarial lesion confirmed to be of tubercular etiology on biopsy, and both lesions subsequently responded to antitubercular treatment.

Reliability of 18F-FDG PET Metabolic Parameters Derived Using Simultaneous PET/MRI and Correlation With Prognostic Factors of Invasive Ductal Carcinoma: A Feasibility Study.

OBJECTIVE: The objective of our study was to correlate semiquantitative PET parameters-standardized uptake value (SUV) and total lesion glycolysis (TLG)-derived in simultaneous PET/MRI using MRI-based attenuation correction with clinical and histopathologic prognostic factors in patients with breast cancer. MATERIALS AND METHODS: Eighty-two invasive ductal carcinomas in 69 women were included in the study. All the subjects underwent whole-body (WB) PET/MRI (supine WB mode) and dedicated PET/MRI of the breast (prone breast imaging mode) for staging on a simultaneous PET/MRI system. The SUV and TLG values were calculated from 18F-FDG PET data using MRI-based attenuation correction (2-point Dixon sequence for tissue segmentation). Relationships between SUV and TLG values and clinical and histopathologic parameters (i.e., tumor size, tumor grade, Ki-67 status, and hormonal receptor expression status) were evaluated using Spearman correlation coefficient analysis. RESULTS: A significant correlation was observed between mean SUV (SUVmean) and maximum SUV (SUVmax) values derived with WB PET and regional PET of the breasts performed simultaneously with MRI (r = 0.88 and 0.89, respectively). A significant difference (p < 0.05) was observed in SUVmean, SUVmax, and TLG values between the grades and molecular subtypes of breast cancer. High SUVmean, SUVmax, and TLG values were found to correlate with larger tumor size (p < 0.01), higher proliferation index (p < 0.05), higher grade (p < 0.01), and triple-negative hormonal receptor status (p < 0.01, p < 0.05). CONCLUSION: Semiquantitative FDG parameters derived with MRI-based attenuation correction in simultaneous PET/MRI are reliable and correlate with clinicopathologic features such as grade as well as subtype and thus could be used in the prognostication of breast cancer.

Association of pharmacokinetic and metabolic parameters derived using simultaneous PET/MRI: Initial findings and impact on response evaluation in breast cancer.

PURPOSE: To study relationships among pharmacokinetic and 18F-fluorodeoxyglucose (18F-FDG) PET parameters obtained through simultaneous PET/MRI in breast cancer patients and evaluate their combined potential for response evaluation. METHODS: The study included 41 breast cancer patients for correlation study and 9 patients (pre and post therapy) for response evaluation. All patients underwent simultaneous PET/MRI with dedicated breast imaging. Pharmacokinetic parameters and PET parameters for tumor were derived using an in- house developed and vendor provided softwares respectively. Relationships between SUV and pharmacokinetic parameters and clinical as well as histopathologic parameters were evaluated using Spearman correlation analysis. Response to chemotherapy was derived as percentage reduction in size and in parameters post therapy. RESULTS: Significant correlations were observed between SUVmean, max, peak, TLG with Ktrans (ρ=0.446, 0.417, 0.491, 0.430; p≤0.01); with Kep(ρ=0.303, ρ=0.315, ρ=0.319; p≤0.05); and with iAUC(ρ=0.401, ρ=0.410, ρ=0.379; p≤0.05, p≤0.01). The ratio of ve/iAUC showed significant negative correlation to SUVmean, max, peak and TLG (ρ=0.420, 0.446, 0.443, 0.426; p≤0.01). Ability of SUV as well as pharmacokinetic parameters to predict response to therapy matched the RECIST criteria in 9 out of 11 lesions in 9 patients. Maximum post therapy quantitative reduction was observed in SUVpeak, TLG and Ktrans. CONCLUSION: Simultaneous PET/MRI enables illustration of close interactions between glucose metabolism and pharmacokinetic parameters in breast cancer patients and potential of their simultaneity in response assessment to therapy.

PSMA Expression in Multinodular Thyroid Neoplasm on Simultaneous Ga-68-PSMA PET/MRI.

PSMA PET is increasingly being used in imaging of recurrent prostate carcinoma. A case with suspected recurrent Prostate carcinoma (PCa), raised PSA (Prostate specific antigen) and suspected spinal metastases was referred for whole body Ga-68-PSMA PET/MRI. The study revealed PSMA avid recurrent prostate mass and extensive osseous metastases. Abnormal PSMA uptake in the thyroid gland prompted USG-guided FNAC which revealed Hurthle cell neoplasm. Histopathological examination (HPE) of excised gland showed multiple Hurthle cell adenomas in both lobes of thyroid along with foci of papillary thyroid carcinoma which on immunohistochemistry were thyroglobulin positive and PSA negative.

Potential for differentiation of glioma recurrence from radionecrosis using integrated 18F-fluoroethyl-L-tyrosine (FET) positron emission tomography/magnetic resonance imaging: A prospective evaluation.

PURPOSE: To assess the utility of 18F-fluoroethyl-L-tyrosine (FET) positron emission tomography/magnetic resonance imaging (PET/MRI) in distinguishing recurrence from radionecrosis. MATERIALS AND METHODS: Thirty-two patients (25 males, 7 females) of glioma who had already undergone surgery/chemoradiotherapy and had enhancing brain lesions suspicious of recurrence were evaluated using integrated 18F-FET PET/MRI, and followed up with histopathology or clinical follow-up and/or MRI/PET/MRI imaging. Manually drawn regions of interest over areas of maximal enhancement or FET uptake were used to calculate tumor to background ratios [TBRmax, TBRmean], choline: creatine ratio [Cho: Cr ratio], normalized relative cerebral blood volume [N rCBVmean] and apparent diffusion coefficient [ADCmean]. Correlations were evaluated using Pearson's coefficient. Accuracy of each parameter was calculated using independent t-test and receiver operator curve (ROC) analysis while utility of all four parameters together using multivariate analysis of variance (MANOVA) for differentiating recurrence vs. radionecrosis was evaluated. Positive histopathology and imaging/clinical follow up served as the gold standard. RESULTS: Twenty-four of the 32 patients were diagnosed with recurrent disease and 8 with radiation necrosis. Significant correlations were observed between TBRmaxand N rCBVmean (ρ =0.503; P = 0.003), TBRmean, and N rCBVmean (ρ =0.414; P = 0.018), TBRmaxand ADCmean (ρ = -0.52; P = 0.002), and TBRmeanand ADCmean(ρ = -0.518; P = 0.002). TBRmax, TBRmean, ADCmean, Cho: Cr ratios, and N rCBVmeanwere significant in differentiating recurrence from radiation necrosis with an accuracy of 94.1%, 88.2%, 80.4%, 96.4%, and 89.9%, respectively. MANOVA indicated that combination of all parameters demonstrated better evaluation of recurrence vs. necrosis than any single parameter. The diagnostic accuracy, sensitivity, and specificity using all MRI parameters were 93.75%, 96%, and 85.7%, and using all FET PET/MRI parameters was 96.87%, 100%, and 85.7%, respectively. CONCLUSIONS: Synergetic effect of multiple MR parameters evaluated together in addition to FET PET uptake highlights the fact that integrated 18F-FET PET/MRI might have the potential to impact management of patients with glioma by timely and conclusive recognition of true recurrence from radiation necrosis.

Role of pharmacokinetic parameters derived with high temporal resolution DCE MRI using simultaneous PET/MRI system in breast cancer: A feasibility study.

PURPOSE: To evaluate the reliability of pharmacokinetic parameters like Ktrans, Kep and ve derived through DCE MRI breast protocol using 3T Simultaneous PET/MRI (3Tesla Positron Emission Tomography/Magnetic Resonance Imaging) system in distinguishing benign and malignant lesions. MATERIALS AND METHODS: High temporal resolution DCE (Dynamic Contrast Enhancement) MRI performed as routine breast MRI for diagnosis or as a part of PET/MRI for cancer staging using a 3T simultaneous PET/MRI system in 98 women having 109 breast lesions were analyzed for calculation of pharmacokinetic parameters (Ktrans, ve, and Kep) at 60s time point using an in-house developed computation scheme. RESULTS: Receiver operating characteristic (ROC) curve analysis revealed a cut off value for Ktrans, Kep, ve as 0.50, 2.59, 0.15 respectively which reliably distinguished benign and malignant breast lesions. Data analysis revealed an overall accuracy of 94.50%, 79.82% and 87.16% for Ktrans, Kep, ve respectively. Introduction of native T1 normalization with an externally placed phantom showed a higher accuracy (94.50%) than without native T1 normalization (93.50%) with an increase in specificity of 87% vs 84%. CONCLUSION: Overall the results indicate that reliable measurement of pharmacokinetic parameters with reduced acquisition time is feasible in a 3TMRI embedded PET/MRI system with reasonable accuracy and application may be extended to exploit the potential of simultaneous PET/MRI in further work on breast cancer.

68Ga-PSMA Uptake in Hepatocellular Carcinoma.

Ga-PSMA based integrated PET/MRI is emerging as a novel imaging technique for the staging of prostate carcinoma. We report a case of a 77-year-old man with raised prostate-specific antigen who presented to us for Glu-NH-CO-NH-Lys-(Ahx)-[Ga-(HBED-CC)] (Ga-PSMA) simultaneous PET/MRI scan for prostate cancer evaluation. A PSMA avid hepatic lesion on the background of cirrhotic liver was noted apart from PSMA avid lesion in the peripheral gland of the prostate. On histopathological examination, the hepatic lesion turned out to be hepatocellular carcinoma.

Glioma Recurrence Versus Radiation Necrosis: Single-Session Multiparametric Approach Using Simultaneous O-(2-18F-Fluoroethyl)-L-Tyrosine PET/MRI.

PURPOSE: This study aimed to investigate the potential of hybrid gadolinium (Gd)-enhanced F-fluoroethyl-L-tyrosine (F-FET) PET/MRI in distinguishing recurrence from radiation necrosis using simultaneously acquired multiple structural and functional parameters. METHODS: Twenty-six patients (5 female and 21 male patients; mean ± SD age, 51.58 ± 15.97 years) with single or multiple contrast-enhancing brain lesions (n = 32) on MRI after surgery and radiation therapy were evaluated with simultaneously acquired Gd-enhanced F-FET PET/MRI. They were then followed up with resurgery and histopathological diagnosis (n = 9) and/or clinical/MRI- or PET/MRI-based imaging follow-up (n = 17). PET/MR images were analyzed using manually drawn regions of interest over areas of maximal contrast enhancement and/or FET uptake. Maximum target-to-background ratio (TBRmax), mean target-to-background ratio (TBRmean), and choline-to-creatine (Cho/Cr) ratios as well as normalized mean relative cerebral blood volume (rCBVmean) and mean apparent diffusion coefficient (ADCmean) were determined. The accuracy of each parameter individually and in various possible combinations for differentiating recurrence versus radiation necrosis was evaluated using 2-tailed independent samples Student t test, multivariate analysis of variance, and multivariate receiver operating characteristic analysis. Positive histopathological finding and long-term imaging/clinical follow-up suggestive of disease progression served as criterion standard. RESULTS: Of 26 patients, 19 were classified as recurrence, with 7 patients showing radiation necrosis. Individually, TBRmax, TBRmean, ADCmean, and Cho/Cr ratios as well as normalized rCBVmean was significant in differentiating recurrence from radiation necrosis, with an accuracy of 93.8% for TBRmax, 87.5% for TBRmean, 81.3% for ADCmean, 96.9% for Cho/Cr ratio, and 90.6% for normalized rCBVmean. The accuracy of both normalized rCBVmean and ADCmean was improved in combination with TBRmax or Cho/Cr ratio. However, TBRmax (or TBRmean) with Cho/Cr ratio yielded the highest accuracy, approaching up to 97%. Furthermore, maximum area under the curve is achieved with the combination of TBRmean, CBV, and Cho/Cr values. CONCLUSIONS: Our findings suggest that FET uptake with Cho/Cr ratio and normalized rCBVmean could be most useful to distinguish primary glioma recurrence from radiation necrosis. Hybrid simultaneous multiparametric F-FET PET/MRI might play a significant role in the evaluation of patients with suspected glioma recurrence.

Integrated (18)F-fluorodeoxyglucose positron emission tomography magnetic resonance imaging ((18)F-FDG PET/MRI), a multimodality approach for comprehensive evaluation of dementia patients: A pictorial essay.

Dementia, caused by irreversible neurodegenerative disorders such as Alzheimer's disease or reversible non-degenerative conditions, is rapidly becoming one of the most alarming health problems in our aging society. This cognitive disorder associated with a multitude of clinical differentials with overlapping clinical, pathological, and imaging features is difficult to diagnose and treat, as it often presents late after significant neuronal damage has already occurred. Novel disease-modifying treatments being developed will have to be corroborated with innovative imaging biomarkers so that earlier reliable diagnosis can be made and treatment initiated upon. Along with new specific PET radiotracers, integrated PET/MRI with combined methodological advantage and simultaneously acquired structural-cum-functional information may help achieve this goal. The present pictorial essay details our experiences with PET/MRI in dementing disorders, along with reviewing recent advances and future scope.

Somatostatin receptor-positive granulomatous inflammation mimicking as meningioma on simultaneous PET/MRI.

Positron imaging with radiolabeled synthetic somatostatin receptor analogs such as Ga DOTATATE (Gallium-68-1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetra acetic acid-DPhe1,Tyr3-octreotate) is used for diagnosis and target volume delineation of intracranial meningiomas. We report a case of a somatostatin receptor-positive extra-axial necrotizing granulomatous inflammation mimicking as meningioma on simultaneous Ga DOTATATE PET/MRI. This case illustrates a Ga DOTATATE-positive granuloma bearing a striking resemblance to meningioma.

Simultaneous whole-body ¹8F-FDG PET-MRI in primary staging of breast cancer: a pilot study.

PURPOSE: Accurate initial staging in breast carcinoma is important for treatment planning and for establishing the likely prognosis. The purpose of this study was to assess the utility of whole body simultaneous (18)F-FDG PET-MRI in initial staging of breast carcinoma. METHODS: 36 patients with histologically confirmed invasive ductal carcinoma underwent simultaneous whole body (18)F-FDG PET-MRI on integrated 3T PET-MR scanner (Siemens Biograph mMR) for primary staging. Primary lesion, nodes and metastases were evaluated on PET, MRI and PET-MRI for lesion count and diagnostic confidence (DC). Kappa co relation analysis was done to assess agreement between the satellite, nodal and metastatic lesions detected by PET and MRI. Histopathology, clinical/imaging follow-up served as the reference standard. RESULTS: 36 patients with 37 histopathologically proven index breast cancer were retrospectively studied. Of 36 patients, 25 patients underwent surgery and 11 patients received systemic therapy. All index cancers were seen on PET and MR. Fused PET-MRI showed highest diagnostic confidence score of 5 as compared to PET (median 4; range 3-5) and MRI (median 4; range 4-5) alone. 2/36 (5.5%) patients were detected to have unsuspected contralateral synchronous cancer. 47 satellite lesions were detected on DCE MRI of which 23 were FDG avid with multifocality and multicentricity in 21 (58%) patients. Kappa co relation analysis revealed fair agreement for satellite lesion detection by the two modalities (κ=0.303; P=0.003). The study showed a sensitivity of 60% and 93.3% on PET and MRI respectively for detection of axillary lymph nodes with a specificity of 91% for both and a false negative rate of 6.7% on MRI and 40% on PET. Kappa co relation analysis between PET and MRI for all the lymph nodes detected revealed fair agreement by the two modalities (κ=0.337; P=0.000). Combined PET-MRI increased diagnostic confidence for nodal involvement (median DC 5, range 4-5; P<0.05). Distant metastases were found in 8/36 (22%) patients at the time of diagnosis with a total of 91 metastatic lesions on PET (DC≥4) and 105 on MRI (DC≥4), the difference being statistically significant (P=0.001) while Kappa co relation analysis showed significant agreement between the two modalities (κ=0.667; P=0.000). Overall PET-MRI led to a change in management in 12 (33.3%) patients. CONCLUSION: In this pilot study, simultaneous (18)F-FDG PET-MR, has been found to be useful in whole-body initial staging of breast cancer patients.

Simultaneous PET/MRI: Impact on cancer management-A comprehensive review of cases.

The metabolic mapping of malignancy in whole body in a single examination by PET/CT has gained widespread acceptance where the CT provides an anatomical correlate for the PET. MRI offers advantage over CT in providing better anatomical information owing to its high soft tissue resolution especially in brain, liver, neck, pelvis and bone marrow. Simultaneous PET/MRI is a new multimodal imaging modality that is expected to improve the diagnostic performance of imaging wherein better anatomical and metabolic information can be acquired at the same time and space during a single examination time. Also, MR attributes like diffusion, perfusion and spectroscopy may further add to its diagnostic potential. In this article, we present our initial experience in illustrated cases done with simultaneous PET/MRI and outline its potential for several clinical applications in oncology.