Where there is no PET/CT

EJNMMI Research

Background: Hybrid positron emission tomography and magnetic resonance imaging (PET/MRI) scanners are increasingly used for both clinical and preclinical imaging. Especially functional MRI sequences such as diffusionweighted imaging (DWI) are of great interest as they provide information on a molecular level, thus, can be used as surrogate biomarkers. Due to technical restrictions, MR sequences need to be adapted for each system to perform reliable imaging. There is, to our knowledge, no suitable DWI protocol for 1 Tesla PET/MRI scanners. We aimed to establish such DWI protocol with focus on the choice of b values, suitable for longitudinal monitoring of tumor characteristics in a rat liver tumor model. Material and methods: DWI was first performed in 18 healthy rat livers using the scanner-dependent maximum of 4 b values (0, 100, 200, 300 s/mm 2). Apparent diffusion coefficients (ADC) were calculated from different b value combinations and compared to the reference measurement with four b values. T2-weighted MRI and optimized DWI with best agreement between accuracy, scanning time, and system performance stability were used to monitor orthotopic hepatocellular carcinomas (HCC) in five rats of which three underwent additional 2-deoxy-2-(18 F)fluoro-Dglucose(FDG)-PET imaging. ADCs were calculated for the tumor and the surrounding liver parenchyma and verified by histopathological analysis. Results: Compared to the reference measurements, the combination b = 0, 200, 300 s/mm 2 showed the highest correlation coefficient (r s = 0.92) and agreement while reducing the acquisition time. However, measurements with less than four b values yielded significantly higher ADCs (p < 0.001). When monitoring the HCC, an expected drop of the ADC was observed over time. These findings were paralleled by FDG-PET showing both an increase in tumor size and uptake heterogeneity. Interestingly, surrounding liver parenchyma also showed a change in ADC values revealing varying levels of inflammation by immunohistochemistry. Conclusion: We established a respiratory-gated DWI protocol for a preclinical 1 T PET/MRI scanner allowing to monitor growth-related changes in ADC values of orthotopic HCC liver tumors. By monitoring the changes in tumor ADCs over time, different cellular stages were described. However, each study needs to adapt the protocol further according to their question to generate best possible results.

Clinics in oncology, 2017

WB-DW MRI is done on both 1.5T and 3.0T MRI systems with the use of 4-5 station coils without the use of any contrast with images taken from head to mid tibia level and are acquired axially in free breathing state. Diffusion sequences are applied in X,Y and Z axis before and after 180 degree inversion pulse to have a fat saturation image along with diffusion sensitivity b values of 0,400,800mm 2 /sec. Data obtained is reformatted in multi planar manner as whole body images in coronal planes and inverted as black and white grey scale images (Figure1a and b) for analysis. ADC values for any region of interest are determined for estimation of tumor cellularity and expressed in units of 10mm 2 /s -3mm 2 /s. Another parameter used is lesion to spinal cord ratio determined on high b value image by using ROI technique. We searched the Pub med for studies done for correlation and comparison of PET-CT and WB-DWMRI and reviewed the results. 19 studies from current literature were found out which compared the results of both the modalities in patients of cancer for staging and suspected metastasis and also other myeloproliferative disorders (Table ). All these studies were found to be having a common conclusion that WB-DWMRI can be used as a diagnostic test to diagnose and stage the disease and also to assess treatment response in such patients for which quantities DWMRI can be used as biomarker for early assessment of response to treatment. Mori "et al". [3] performed prospectively 18F-FDG PET-CT and DWMRI on 104 patients with pulmonary nodules of which 106 were proven malignant. SUV values and SUV CR values were obtained to determine the nature of lesion on PET-CT and ADC min values are determined on DW

Proceedings of the 2022 5th International Conference on Digital Medicine and Image Processing

The idea of an integrated nuclear medicine unit consisting of a PET-CT scanner with a practical source of radioisotopes such as a cyclotron to operate efficiently in Palestinian health system is almost impossible due to several reasons, mainly political and financial issues. The goal of this study is to find a safe, valid, and widely available modality as an alternative to help oncologists and patients; we proposed a whole-body diffusion MRI protocol (WB-DWI MRI) A 33 oncological patients, 60% male (n = 20) and 40% female (n = 13), age 18-74 years with a mean age of 48 years old participated in our study for a PET-CT and WB-DWI MRI scan. Participants already diagnosed to have primary tumors including non-Hodgkin's lymphoma (NHL), Hodgkin's lymphoma, endometrial cancer, prostate cancer, pancreatic cancer, gastric cancer, thyroid cancer, idiopathic pathological fractures and skin lesions suspected to be melanoma. Our results shows that PET-CT demonstrated 181 hypermetabolic lesion distributed in the four zones (head-neck, chest, abdomen-pelvis and musculoskeletal), was detected by WB-DWI This work is licensed under a Creative Commons Attribution International 4.0 License.

Journal of the Belgian Society of Radiology, 2014

Purpose: To evaluate the effectiveness of wb-Mri for the detection of primary and metastatic lesions in comparison to peT-cT in patients with newly diagnosed malignancies Material and Methods: in this prospective study, 36 patients were evaluated between august 2008 and october 2012. The findings of wb-Mri (dwi and fat saturated T2 weighted images) were compared to the findings of peT-cT regarding the primary lesions and metastasis. sensitivity, specificity, positive and negative predictive values were calculated. To assess the aggreement between peT-cT and wb-Mri, kappa analysis was performed. Results: The sensitivity, specificity, positive and negative predictive values for wb-dwi for the detection of primary and metastatic lesions in comparison to peT-cT were 96%, 89%, 97% and 84%, respectively.These are calculated as 96%, 56% , 90% and 77%, for fat-saturated T2w images. according to kappa analysis, the agreement between peT-cT and wb-dwi was excellent (κ = 0.83), but between peT-cT and fat-saturated T2 weighted images, it was moderate (κ = 0.58). Conclusion: providing both morphogical and functional data, wb-Mri with dwi is emerging as a promising alternative imaging tool in the evaluation of cancer patients and may become complementary to peT-cT in several clinical applications.

2011

Tumour staging in cancer patients generally entails a multimodality imaging approach. Whole-body (WB) imaging techniques may, however, be more time- and cost-effective than a multimodality approach. 2-fluorine-18-fluoro-2-deoxy-D-glucose positron emission tomography (18FDG-PET), computed tomography (CT) and hybrid positron emission tomography and computed tomography (PET/CT) are the most established WB modalities, although new techniques, amongst which diffusion-weighted magnetic resonance imaging (DWI), are emerging. This review aims to evaluate the current evidence for WB-DWI in oncology, to discuss its potential for the WB staging of (colo)rectal cancer and to relate it to the established WB techniques.

European Journal of Radiology, 2012

Objectives: To evaluate if diffusion-weighted MRI (DWI) can replace gadolinium-enhanced MRI (Gd-MRI) for diagnosing liver metastases. The diagnostic accuracy of both techniques alone and in combination are compared. Materials and methods: Sixty-eight patients with histologically proven primary extrahepatic tumors were included in this retrospective study. Lesions included 62 metastases and 130 benign lesions. Three image sets (unenhanced T1 and T2/gadolinium enhanced T1 (Gd-MRI), DWI and combination of both) were reviewed independently by 3 observers. The areas under the receiver operating characteristic curves (A z ), sensitivity and specificity for the 3 image sets were compared. The standard of reference was either histopathology or multi-modality and clinical follow-up. Results: Pooled data showed higher diagnostic accuracy for the combined set (A z = 0.93) compared to Gd-MRI (p = 0.001) and DWI (p < 0.0001). No difference was found between the performance of Gd-MRI and DWI (p = 0.09). Sensitivity for the combined set was higher than Gd-MRI (p = 0.0003) and DWI (p = 0.0034). Specificity for DWI was lower than Gd-MRI (p < 0.0001) and the combined set (p < 0.0001). Conclusion: The diagnostic performance of DWI is equal to that of Gd-MRI. DWI alone can be used in patients where gadolinium contrast administration is not allowed. Combination of Gd-MRI and DWI significantly increases diagnostic accuracy.

La radiologia medica, 2011

Purpose. Our aim was to assess the overall diagnostic accuracy of magnetic resonance diffusion-weighted whole-body imaging with background signal suppression (MR-DWIBS) compared with ([ 18 F]-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT), considered the reference standard of whole-body tumour imaging modalities, in a series of consecutive patients with malignant tumour. Materials and methods. Thirty-eight patients diagnosed with a malignant tumour over a 4-month period were enrolled in this retrospective, observational study. PET/CT and MR-DWIBS images were reviewed in double-blind manner by a nuclear medicine physician and radiologists with 4 years experience. Lesion size, standard uptake value (SUV) and apparent diffusion coefficient (ADC) were measured and calculated for each lesion. Results. The qualitative analysis of MR-DWIBS and [ 18 F]-FDG-PET/CT showed that two patients were negative at both techniques. MR-DWIBS was positive in 36 patients, 34 of whom were positive and two negative at [ 18 F]-FDG-PET/CT, respectively. Two hundred and fiftyfive lesions were identified by MR-DWIBS and 184 by [ 18 F]-FDG-PET/CT, which was a significative discordance. Correlation between SUV and ADC of lesions positive at both techniques was not statistically significant. The mean difference between lesion size in [ 18 F]-FDG-PET/ Riassunto Obiettivo. L'obiettivo del nostro lavoro è stato stabilire il valore di accuratezza diagnostica della whole-body risonanza magnetica (RM)-diffusion weighted whole body imaging with background signal suppression (DWIBS) rispetto alla 18 F-fluor-deossiglucosio (FDG)-tomografia a emissione di positroni (PET)/tomografia computerizzata (TC), considerata il gold standard nell'ambito della diagnostica whole body nell'imaging dei tumori, in un gruppo di pazienti con diagnosi di neoplasia maligna. Materiali e metodi. Sono stati inclusi 38 pazienti con diagnosi di neoplasia maligna in un periodo di 4 mesi. Le immagini PET/TC e RM-DWIBS sono state rivalutate in doppio cieco da un medico nucleare e da un radiologo con 4 anni di esperienza. Per ciascuna lesione sono state valutate dimensioni, standardized uptake value (SUV) e coefficiente di diffusione apparente (ADC). Risultati. La valutazione qualitativa sia della MR-DWIBS che della 18 F-FDG-PET/TC ha riscontrato due soli pazienti negativi per entrambe le tecniche. La RM-DWIBS è risultata positiva in 36 pazienti, di cui 34 erano positivi e 2 risultavano negativi alla 18 F-FDG-PET/TC. Duecentocinquantacinque lesioni sono state identificate con la MR-DWIBS e 184 con 18 F-FDG-PET/TC. È stata dimostrata una discordanza significativa. La correlazione tra SUV e ADC nelle lesioni positive ad entrambe le tecniche non è risultata statisticamente significativa.

World Journal of Radiology, 2012

AIM: To evaluate the role of diffusion-weighted imaging (�WI) in the detection of focal liver lesions (FLLs), using a conventional magnetic resonance imaging (MRI) protocol. METHODS: Fifty-two patients (22 males, average age 55.6 years, range: 25-82 years), studied using a 1.5 Tesla magnetic resonance scanner, were retrospectively analyzed; detection of FLLs was evaluated by considering the number of lesions observed with the following sequences: (1) respiratory-triggered diffusion-weighted single-shot echo-planar (�W SS-EP) sequences; (2) fat-suppressed fast spin-echo (fs-FSE) T2 weighted sequences; (3) steady-state free precession (SSFP) images; and (4) dynamic triphasic gadolinium-enhanced images, acquired with three-dimensional fast spoiled gradient-echo (3� FSPGR). Two radiologists independently reviewed the images: they were blinded to their respective reports. �W SS-EP sequences were compared to fs-FSE, SSFP and dynamic gadolinium-enhanced acquisitions using a t-test. Pairs were compared for the detection of: (1) all FLLs; (2) benign FLLs; (3) malignant FLLs; (4) metastases; and (5) hepatocellular carcinoma (HCC). RESULTS: Interobserver agreement was very good (weighted k = 0.926, CI = 0.880-0.971); on the consensus reading, 277 FLLs were detected. In the comparison with fs-FSE, DW SS-EP sequences had a significantly higher score in the detection of all FLLs, benign FLLs, malignant FLLs and metastases; no statistical difference was observed in the detection of hepatocellular carcinoma (HCCs). In the comparison with SSFP sequences, DW SS-EP had significantly higher scores (P < 0.05) in the detection of all lesions, benign lesions, malignant lesions, metastases and HCC. All FLLs were better detected by dynamic 3� FSGR enhanced acquisition, with P = 0.0023 for reader 1 and P = 0.0086 for reader 2 in the comparison with �W SS-EP sequences; with reference to benign FLLs, �W SS-EP showed lower values than 3� FSPGR enhanced acquisition (P < 0.05). No statistical differences were observed in the detection of malignant lesions and metastases; considering HCCs, a very slight difference was reported by reader 1 (P = 0.049), whereas no difference was found by reader 2 (P = 0.06). CONCLUSION: In lesion detection, �WI had higher scores than T2 sequences; considering malignant FLLs, no statistical difference was observed between �WI and dynamic gadolinium images.