Diffusion-weighted Whole-body Imaging With Background Body Signal Suppression Research Articles

Whole-body-MR imaging including DWIBS in the work-up of patients with head and neck squamous cell carcinoma: A feasibility study

ObjectivesTo assess the feasibility of whole-body magnetic resonance imaging (WB-MRI) including diffusion-weighted whole-body imaging with background-body-signal-suppression (DWIBS) for the evaluation of distant malignancies in head and neck squamous cell carcinoma (HNSCC); and to compare WB-MRI findings with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) and chest-CT. MethodsThirty-three patients with high risk for metastatic spread (26 males; range 48–79 years, mean age 63±7.9 years (mean±standard deviation) years) were prospectively included with a follow-up of six months. WB-MRI protocol included short-TI inversion recovery and T1-weighted sequences in the coronal plane and half-fourier acquisition single-shot turbo spin-echo T2 and contrast-enhanced-T1-weighted sequences in the axial plane. Axial DWIBS was reformatted in the coronal plane. Interobserver variability was assessed using weighted kappa and the proportion specific agreement (PA). ResultsTwo second primary tumors and one metastasis were detected on WB-MRI. WB-MRI yielded seven clinically indeterminate lesions which did not progress at follow-up. The metastasis and one second primary tumor were found when combining 18F-FDG-PET/CT and chest-CT findings. Interobserver variability for WB-MRI was κ=0.91 with PA ranging from 0.82 to 1.00. For 18F-FDG-PET/CT κ could not be calculated due to a constant variable in the table and PA ranged from 0.40 to 0.99. ConclusionsOur WB-MRI protocol with DWIBS is feasible in the work-up of HNSCC patients for detection and characterization of distant pathology. WB-MRI can be complementary to 18F-FDG-PET/CT, especially in the detection of non 18F-FDG avid second primary tumors.

Diffusion-weighted imaging and diffusion-weighted whole-body imaging with background body signal suppression for characterizing esophageal cancer: a case report

PurposeInformation on the extent or structure of esophageal cancer (ESC) is necessary for identifying whether the carcinoma is localized or resectable. Diffusion-weighted imaging (DWI) and diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) are useful for this purpose.Patients and methodsOne case of ESC with dysphagia presented at our hospital. Endoscopic examination revealed an elevated lesion with an ulcer, and stenosis was detected. DWI showed a high-intensity signal extending from the proximal to the distal ends of the carcinoma and extending to the tunica adventitia. A strong signal was also observed using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). DWIBS clearly revealed ESC, and these findings, along with those from DWI, suggested that our case had stage-T3 ESC. FDG-PET did not reveal the detailed structure of the ESC. DWIBS, on the other hand, showed that the signal extended to the tunica adventitia and the lumen of the esophagus.ConclusionThese findings suggest that DWI and DWIBS are useful for the detection and assessment of ESC.

Metastatic Brachial Plexopathy in a Case of Recurrent Breast Carcinoma Demonstrated on (18)F-FDG PET/CT.

This case highlights the importance of recognition of the pattern of metastatic brachialplexopathy in breast cancer patients undergoing 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for evaluation of recurrent disease.This pattern can be appreciated on maximum intensity projection (MIP) and coronal 18F-FDG PET/CTimages as a linear extension of tracer activity from superomedial aspect(supra/infraclavicular) to lateral aspect of the axilla closely related to the subclavian/axillary vessels). A 35-year-old woman diagnosed with infiltrating ductal carcinoma of the right breast had undergone six cycles of neoadjuvant chemotherapy, followed by wide local incision and radiotherapy. She had local recurrence, for which she was operated upon and given chemotherapy. She presented to her oncologist with pain and swelling in the right breast, nodules in the right axilla and restriction of movement of the right upper limb. The patient was referred for 18F-FDG PET/CT to evaluate the extent of recurrent/metastatic disease. Whole-body PET/CT was acquired 1 h following the intravenous injection of 296 MBq of 18F-FDG on a Biograph mCT scanner (Siemens). Evaluation of the MIP image revealed abnormal FDG accumulation at multiple sites in the thorax, along with a linear pattern of FDG uptake in the right lateral aspect of the upper chest (Fig. 1a, arrow). The coronal fused PET/CT image revealed a linear pattern of FDG uptake corresponding to an ill-defined mass extending from just behind the right clavicle into the right axilla (arrow). In addition, abnormal FDG accumulation was seen in a soft tissue density mass in the upper outer quadrant of the right breast, skin of the right breast laterally, both pectoral muscles (discrete foci) and in a few subpectoral nodes. Soft tissue nodular opacities in both lungs showed FDG accumulation suggestive of pulmonary metastasis (Fig. 1b, thick arrow). The patient was referred for magnetic resonance imaging (MRI) to demonstrate the brachial plexus involvement. Coronal diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) revealed a mass in the right axilla, with a b value of 1,000, infiltrating the cord and branches of the right brachial plexus visualised as linear hyperintensities (Fig. 1c, arrow). Fig. 1 Whole-body 18F-FDG PET/CT. a MIP image. b Coronal fused PET/CT image. c DWIBS image Brachial plexopathy in breast cancer patients can be metastatic (because major lymph drainage routes for the breast course through the axilla) or radiation induced, the former being the commoner of the two [1, 2]. Differentiation between the two pathologies is important for appropriate treatment planning. 18F-FDG PET/CT is a useful tool in the evaluation of patients with recurrent or metastatic breast cancer. Recognition of the pattern of brachial plexus involvement is thus essential for accurate interpretation of the 18F-FDG PET/CT study. To date, two case reports and one small case series [3–5] have demonstrated the feasibility of PET for confirming metastatic brachial plexopathy when MRI was suspicious of the same or when the patient was symptomatic for the same. This case highlights the possibility of metastatic brachial plexopathy even when the patient may not be overtly symptomatic for the same. The typical pattern as seen on MIP and coronal images is linear, extending from the superomedial aspect (supra/infraclavicular) to the lateral aspect of axilla closely related to the subclavian/axillary vessels). The commonest finding on computed tomography (CT) is that of an axillary mass, but may range from no remarkable abnormality to minimal thickening [2, 6]. Moreover, CT would not be able to differentiate metastatic from radiation plexopathy [2]. MRI is the first-line imaging modality for evaluating brachial plexopathy [7] and can delineate both normal and abnormal anatomy of the brachial plexus, with the ability to differentiate nerves from the surrounding vessels and soft tissue with greater detail than CT [7–10]. In this case, DWIBS was used to demonstrate the presence of a right axillary mass (discrete mass in relation to the plexus), which is the commonest finding on MRI in patients with metastatic plexopathy

Supplemental value of diffusion‐weighted whole‐body imaging with background body signal suppression (DWIBS) technique to whole‐body magnetic resonance imaging in detection of bone metastases from thyroid cancer

We compared the efficacy of whole-body MRI (WBMRI) with and without diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) using a 3.0-T MR scanner to [18F] fluoro-2-D-glucose positron emission tomography with CT (integrated FDG-PET/CT) for the detection of bone metastases in patients with differentiated thyroid carcinoma (DTC). We examined 23 patients (16 women, 7 men; mean age, 56; range 17-74) with DTC who had undergone total thyroidectomy and were hospitalised to receive [I-131I] therapy. All patients underwent both WBMRI with DWIBS and whole-body FDG-PET/CT. The skeletal system was classified into 13 anatomic segments and assessed for the presence of bone metastases. Bone metastases were verified when positive findings were indicated on at least two imaging modalities: post-treated [131I] whole-body scans, WBMRI without DWIBS (T1-weighted images and short-inversion time inversion recovery images), [18F]-FDG-PET and CT. Bone metastases were confirmed in 78/290 (27%) segments in 20 (87%) of 23 patients. The sensitivities for bone metastases on a segment basis using WBMRI with DWIBS, WBMRI without DWIBS and integrated FDG-PET/CT were 64 of 78 (82%), 50 of 78 (64%) and 62 of 78 (79%), respectively; the difference between values of WBMRI with and without DWIBS was statistically significant (P = 0.0015). The overall accuracies of WBMRI with DWIBS, WBMRI without DWIBS and integrated FDG-PET/CT were 273 of 290 (94%), 261 of 290 (90%) and 272 of 290 (94%), respectively; the difference between values of MRI with and without DWIBS was also statistically significant (P = 0.003). There were only one to three false positive segments and the difference among specificities was not statistically significant in these modalities. Adding DWIBS improved the sensitivity and the overall accuracy of WBMRI using 3.0-T MRI for the detection of bone metastases in patients with DTC. There was no statistically significant difference in diagnostic accuracy between MRI with DWIBS and integrated FDG-PET/CT.

Detecting peritoneal dissemination of ovarian cancer in mice by DWIBS

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) is a relatively new diffusion-based pulse sequence that produces positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG)-like images. We tested the feasibility of DWIBS in detecting peritoneal ovarian cancer in a syngeneic mouse model. Female C57BL/6 mice were injected intraperitoneally with ID8 murine ovarian carcinoma cells. After 11 weeks, the abdomen was imaged by DWIBS. A respiratory gating diffusion-weighted spin-echo echo-planar imaging in abdomen was used (imaging parameters of field of view of 47×47 mm2, matrix size of 64×64 zero-filled to 256×256 and b-value of 1500 s/mm2). We also performed FDG microPET as the reference standard. For comparison of the correlating surface areas of tumor foci on both DWIBS and FDG microPET imaging, two-dimensional region-of-interest (ROI) analysis was performed, and correlation between the two modalities was determined. Mice were also subjected to macroscopic examination for tumor location and pathology after imaging. DWIBS in all mice depicted the tumors as abnormal high signal intensity. The results show that the ROI analysis of correlating lesions reveals relatively high correlation (r²=0.7296) and significant difference (P=.021) between DWIBS and FDG microPET. These results demonstrate that DWIBS has the potential for detecting peritoneal dissemination of ovarian cancer. Nonetheless, due to low ratios of image signal-to-noise and motion artifacts, DWIBS can be limited for lesions near the liver.

Role of combined DWIBS/3D-CE-T1w whole-body MRI in tumor staging: Comparison with PET-CT

ObjectivesTo assess the diagnostic performance of whole-body magnetic resonance imaging (WB-MRI) by diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) in malignant tumor detection and the potential diagnostic advantages in generating fused DWIBS/3D-contrast enhanced T1w (3D-CE-T1w) images. Methods45 cancer patients underwent 18F-FDG PET-CT and WB-MRI for staging purpose. Fused DWIBS/3D-CE T1w images were generated off-line. 3D-CE-T1w, DWIBS images alone and fused with 3D-CE T1w were compared by two readers groups for detection of primary diseases and local/distant metastases. Diagnostic performance between the three WB-MRI data sets was assessed using receiver operating characteristic (ROC) curve analysis. Imaging exams and histopathological results were used as standard of references. ResultsAreas under the ROC curves of DWIBS vs. 3D-CE-T1w vs. both sequences in fused fashion were 0.97, 0.978, and 1.00, respectively. The diagnostic performance in tumor detection of fused DWIBS/3D-CE-T1w images were statistically superior to DWIBS (p<0.001) and 3D-CE-T1w (p≤0.002); while the difference between DWIBS and 3D-CE-T1w did not show statistical significance difference. Detection rates of malignancy did not differ between WB-MRI with DWIBS and 18F-FDG PET-CT. ConclusionWB-MRI with DWIBS is to be considered as alternative tool to conventional whole-body methods for tumor staging and during follow-up in cancer patients.

Aplicação da ressonância magnética de corpo inteiro para o estadiamento e acompanhamento de pacientes com linfoma de Hodgkin na faixa etária infanto-juvenil: comparação entre diferentes sequências

OBJETIVO: Comparar o desempenho das sequências T1, T2, STIR e DWIBS (difusão de corpo inteiro com supressão do sinal de fundo) na identificação de sítios caracterizados como acometidos pelo linfoma de Hodgkin nas cadeias linfonodais, órgãos parenquimatosos e medula óssea, e avaliar a concordância entre os examinadores. MATERIAIS E MÉTODOS: Foram estudados 12 pacientes com diagnóstico confirmado de linfoma de Hodgkin. Os pacientes foram encaminhados para o exame de ressonância magnética, sendo realizadas as sequências ponderadas em T1, T2, STIR e DWIBS. RESULTADOS: O número de sítios linfonodais caracterizados como acometidos nas sequências ponderadas em T1 e T2 apresentaram resultados semelhantes (8 sítios), mas inferiores às sequências STIR e DWIBS (11 e 12 sítios, respectivamente). Quanto ao acometimento da medula óssea, observaram-se os mesmos valores para as sequências T1, T2 e DWIBS (17 lesões), superiores ao valor encontrado na sequência STIR (13 lesões). Quando realizada a comparação entre os examinadores, nota-se que há alta concordância entre as quatro sequências. CONCLUSÃO: As sequências STIR e DWIBS detectaram maior número de linfonodos caracterizados como acometidos. Todas as sequências apresentaram resultados semelhantes na avaliação dos órgãos parenquimatosos e medula óssea. Em todas as sequências analisadas houve alta concordância entre os examinadores.

Assessing extracranial tumors using diffusion-weighted whole-body MRI

Diffusion-weighted magnetic resonance imaging (DWI) provides qualitative and quantitative information about the random motion of water molecules in biological tissues and is able to give functional insight into tissue architecture and pathological changes on a cellular level. This technique has the major advantages of not requiring the administration of contrast agents and not exposing the patient to ionizing radiation. Recent technological advances have led to the development of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) that allows screening of the whole body in 25 minutes. DWI and DWIBS have both revealed great potential in the field of oncology and proved to be useful for detecting and characterizing tumors and evaluating treatment response. This article reviews the basic principles and experimental setup of DWI and DWIBS and illustrates its potential application to the assessment of extracranial tumors. In addition, current limitations and challenges of this promising imaging procedure are discussed.

Diffusion-weighted whole-body imaging with background body signal suppression facilitates detection and evaluation of an anterior rib contusion

We report the magnetic resonance imaging (MRI) findings in a 29-year-old woman with anterior chest wall pain following blunt trauma, with special emphasis on the value of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS). Although a rib contusion could be depicted at (fat-suppressed) T2-weighted MRI, anatomical localization and assessment of lesion extent were superior and more straightforward at DWIBS. Thus, this report shows the utility of adding DWIBS to an MRI protocol for anterior chest wall evaluation.

Cervical lymph nodes with or without metastases from oral squamous carcinoma: a correlation of MRI findings and histopathologic architecture

The aim of this study was to describe the magnetic resonance images (MRIs) of the architecture of metastatic lymph nodes as well as healthy lymph nodes and to correlate the images with the histopathologic architecture of the lymph nodes from oral squamous cell carcinoma. The signal intensities of 98 cervical lymph nodes from 20 patients with oral squamous cell carcinoma were evaluated on T2-weighted and diffusion-weighted whole-body imaging with background body signal suppression (DWIBS). The MRI findings were compared with the histopathologic architecture. On T2-weighted images, very hyperintense and/or isointense areas were specific findings for lymph nodes containing metastases from oral squamous cell carcinoma. Histopathology indicated that these areas corresponded to cystic degeneration or keratinization. Using DWIBS images with inverted black-and-white image contrast, cystic degeneration, keratinization, fibrous tissue, tumor tissue, and lymphoid tissue were either hypointense or intermediate in intensity. On T2-weighted images, very hyperintense and/or isointense areas were characteristic findings for lymph nodes containing metastases from oral squamous cell carcinoma. This suggests cystic degeneration or keratinization within the affected lymph nodes. Using DWIBS images, it was difficult to differentiate metastatic from benign lymph nodes.

A new phantom using polyethylene glycol as an apparent diffusion coefficient standard for MR imaging

In recent years, magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) has seen wide clinical use, such as for early detection of cerebrovascular diseases and whole body screening for tumors. The apparent diffusion coefficient (ADC) standard phantom, which mimics the ADC values of several lesions in the body, is indispensable for the development of new pulse sequences for DWI, such as diffusion-weighted whole-body imaging with background body-signal suppression (DWIBS). However, information on the ADC values of the previously reported ADC standard phantoms is limited, because these phantoms were made using only a few different materials at a limited range of concentrations, and the ADC values were measured only at certain temperatures. It has been considered difficult, if not impossible, to create a phantom that provides arbitrary ADC values, because it is difficult to calculate the concentrations of the materials and the temperature at ADC measurement. In this study, we used polyethylene glycol (PEG) as a phantom material, and developed an empirical formula to calculate the PEG concentration at any measurement temperature to obtain arbitrary ADC values of the phantom. DWI images of phantoms made using seven different PEG concentrations were taken under heating from 17 to 46 degrees C at 1 degrees C intervals. Using ADC values calculated from these DWI images, we developed two empirical formulas: i) an empirical formula to calculate the ADC values of phantoms made using any PEG concentration at any measurement temperature; and ii) an empirical formula to calculate PEG concentrations to obtain arbitrary ADC values at any measurement temperature. We inspected the accuracy of these empirical formulas by newly made PEG phantoms. A comparison between the ADC values calculated with the empirical formulas and the measured ADC values confirmed the high accuracy of these formulas. PEG phantoms are safe, inexpensive and easy to make, compared with the previously reported ADC standard phantoms. Our empirical formulas enable us to calculate PEG concentrations that provide arbitrary ADC values at any measurement temperature. The empirical formulas could be used within a range of ADC values from 0.37x10(-3) to 3.67x10(-3) mm(2)/s, PEG concentrations from 0 to 120 mM, and measurement temperatures from 18 to 45 degrees C. Using these formulas, it would be possible to make standard phantoms that mimic the ADC values of any clinical lesions. The PEG phantom might thus be an excellent new ADC standard phantom for MRI with DWI.

Whole-body diffusion-weighted magnetic resonance imaging

Diffusion-weighted magnetic resonance imaging (DWI) provides information on the diffusivity of water molecules in the human body. Technological advances and the development of the concept of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) have opened the path for routine clinical whole-body DWI. Whole-body DWI allows detection and characterization of both oncological and non-oncological lesions throughout the entire body. This article reviews the basic principles of DWI and the development of whole-body DWI, illustrates its potential clinical applications, and discusses its limitations and challenges.

Diagnostic performance of diffusion-weighted magnetic resonance imaging in esophageal cancer

The purpose of this study was to assess the value of diffusion-weighted magnetic resonance imaging (DWI) in detecting esophageal cancer and assessing lymph-node status, compared with histopathological results. DWI was prospectively performed in 24 consecutive patients with esophageal cancer, using the diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) sequence. DWIBS images were fused with T2-weighted images, and independently and blindly evaluated by three board-certified radiologists, regarding primary tumor detectability and lymph-node status. Apparent diffusion coefficients (ADCs) of the primary tumor and lymph nodes were also measured. Average primary tumor detection rate was 49.4%, average patient-based sensitivity and specificity for the detection of lymph-node metastasis were 77.8 and 55.6%, and average lymph-node group-based sensitivity and specificity were 39.4 and 92.6%. There were no interobserver differences among the three readers (P < 0.0001). Mean ADC of detected primary tumors was 1.26 +/- 0.29x10(-3) mm(2)/s. Mean ADC of metastatic lymph nodes (1.46 +/- 0.35x10(-3) mm(2)/s) was significantly higher (P < 0.0001) than that of nonmetastatic lymph nodes (1.15 +/- 0.24 mm(2)/s), but ADCs of both groups overlapped. In conclusion, this study suggests that DWI only has a limited role in detecting esophageal cancer and nodal staging.

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS): features and potential applications in oncology

Diffusion-weighted magnetic resonance imaging (DWI) provides functional information and can be used for the detection and characterization of pathologic processes, including malignant tumors. The recently introduced concept of “diffusion-weighted whole-body imaging with background body signal suppression” (DWIBS) now allows acquisition of volumetric diffusion-weighted images of the entire body. This new concept has unique features different from conventional DWI and may play an important role in whole-body oncological imaging. This review describes and illustrates the basics of DWI, the features of DWIBS, and its potential applications in oncology.Electronic supplementary materialThe online version of this article (doi:10.1007/s00330-008-0968-z) contains supplementary material, which is available to authorized users.

Practical Aspects of Assessing Tumors Using Clinical Diffusion-weighted Imaging in the Body

Diffusion-weighted magnetic resonance (MR) imaging (DWI) is increasingly applied to evaluate tumors in the abdomen and pelvis. However, DWI is susceptible to a variety of artifacts that arise from motion, use of strong gradient pulses, and echo-planar imaging technique. We discuss practical issues to help radiologists optimize the use of DWI to evaluate tumors in the body, including breath-hold DWI, multiple-acquisition non-breath-hold DWI, and diffusion-weighted whole-body imaging with background body signal suppression (DWIBS). Considerations of meticulous technique, sequence optimization, and quality assurance are emphasized for consistent acquisition of high quality images. We illustrate the potential use of these techniques to detect and characterize tumors and to monitor treatment effects.

Quantification of left ventricular volume from cardiac cine MRI using active contour model combined with gradient vector flow

To evaluate the clinical impact of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) in staging of malignant lymphoma.Twenty-three patients with proven malignant lymphomas were prospectively enrolled. DWIBS (b = 0, 1000 s/mm2) examinations and PET-CT were performed respectively on an Intera 1.5 T unit and a Gyroscan PET-CT scan (Philips Medical system, Best, the Netherland). The criteria for positive node involvement were a size over 10 mm or an apparent diffusion coefficient (ADC) value under 0.75 10−3 mm2/s for nodes under 10 mm. For extranodal analysis, a high or heterogeneous signal on DWIBS was considered as positive. In cases of discordance, the reference standard for each region or organ was established at 6 months after the diagnosis according to all available clinical, biological information, as well as histological evidence or follow-up to prove or disprove the presence of disease.DWIBS and PET-CT results were congruent in 333 node regions on the 345 areas analyzed, with excellent agreement (κ = 0.97, P < 0.0001). From 433 organs analyzed (one patient had splenectomy) extranodal disease was detected in 22 organs on DWIBS. The two imaging techniques agreed on 430 organs (κ = 0.99, P < 0.0001). Finally, Ann Arbor stages based on DWIBS and those of PET/CT were in agreement for 23 patients.For malignant lymphoma in a pre-therapeutic context, agreement between diffusion-weighted whole-body imaging and PET/CT is high for Ann Arbor staging.

Letter from the Guest Editor

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) is a relatively new diffusion-based pulse sequence that produces positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG)-like images. We tested the feasibility of DWIBS in detecting peritoneal ovarian cancer in a syngeneic mouse model. Female C57BL/6 mice were injected intraperitoneally with ID8 murine ovarian carcinoma cells. After 11 weeks, the abdomen was imaged by DWIBS. A respiratory gating diffusion-weighted spin-echo echo-planar imaging in abdomen was used (imaging parameters of field of view of 47×47 mm2, matrix size of 64×64 zero-filled to 256×256 and b-value of 1500 s/mm2). We also performed FDG microPET as the reference standard. For comparison of the correlating surface areas of tumor foci on both DWIBS and FDG microPET imaging, two-dimensional region-of-interest (ROI) analysis was performed, and correlation between the two modalities was determined. Mice were also subjected to macroscopic examination for tumor location and pathology after imaging. DWIBS in all mice depicted the tumors as abnormal high signal intensity. The results show that the ROI analysis of correlating lesions reveals relatively high correlation (r²=0.7296) and significant difference (P = .021) between DWIBS and FDG microPET. These results demonstrate that DWIBS has the potential for detecting peritoneal dissemination of ovarian cancer. Nonetheless, due to low ratios of image signal-to-noise and motion artifacts, DWIBS can be limited for lesions near the liver.

A procedure for nonlinear least squares refinement in adverse practical conditions

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) is a relatively new diffusion-based pulse sequence that produces positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG)-like images. We tested the feasibility of DWIBS in detecting peritoneal ovarian cancer in a syngeneic mouse model. Female C57BL/6 mice were injected intraperitoneally with ID8 murine ovarian carcinoma cells. After 11 weeks, the abdomen was imaged by DWIBS. A respiratory gating diffusion-weighted spin-echo echo-planar imaging in abdomen was used (imaging parameters of field of view of 47×47 mm2, matrix size of 64×64 zero-filled to 256×256 and b-value of 1500 s/mm2). We also performed FDG microPET as the reference standard. For comparison of the correlating surface areas of tumor foci on both DWIBS and FDG microPET imaging, two-dimensional region-of-interest (ROI) analysis was performed, and correlation between the two modalities was determined. Mice were also subjected to macroscopic examination for tumor location and pathology after imaging. DWIBS in all mice depicted the tumors as abnormal high signal intensity. The results show that the ROI analysis of correlating lesions reveals relatively high correlation (r²=0.7296) and significant difference (P = .021) between DWIBS and FDG microPET. These results demonstrate that DWIBS has the potential for detecting peritoneal dissemination of ovarian cancer. Nonetheless, due to low ratios of image signal-to-noise and motion artifacts, DWIBS can be limited for lesions near the liver.