Non-small cell lung cancer: whole-body MR examination for M-stage assessment--utility for whole-body diffusion-weighted imaging compared with integrated FDG PET/CT

Inter- and Intra-Observer Repeatability of Quantitative Whole-Body, Diffusion-Weighted Imaging (WBDWI) in Metastatic Bone Disease

Quantitative whole-body diffusion-weighted MRI (WB-DWI) is now possible using semi-automatic segmentation techniques. The method enables whole-body estimates of global Apparent Diffusion Coefficient (gADC) and total Diffusion Volume (tDV), both of which have demonstrated considerable utility for assessing treatment response in patients with bone metastases from primary prostate and breast cancers. Here we investigate the agreement (inter-observer repeatability) between two radiologists in their definition of Volumes Of Interest (VOIs) and subsequent assessment of tDV and gADC on an exploratory patient cohort of nine. Furthermore, each radiologist was asked to repeat his or her measurements on the same patient data sets one month later to identify the intra-observer repeatability of the technique. Using a Markov Chain Monte Carlo (MCMC) estimation method provided full posterior probabilities of repeatability measures along with maximum a-posteriori values and 95% confidence intervals. Our estimates of the inter-observer Intraclass Correlation Coefficient (ICCinter) for log-tDV and median gADC were 1.00 (0.97-1.00) and 0.99 (0.89-0.99) respectively, indicating excellent observer agreement for these metrics. Mean gADC values were found to have ICCinter = 0.97 (0.81-0.99) indicating a slight sensitivity to outliers in the derived distributions of gADC. Of the higher order gADC statistics, skewness was demonstrated to have good inter-user agreement with ICCinter = 0.99 (0.86-1.00), whereas gADC variance and kurtosis performed relatively poorly: 0.89 (0.39-0.97) and 0.96 (0.69-0.99) respectively. Estimates of intra-observer repeatability (ICCintra) demonstrated similar results: 0.99 (0.95-1.00) for log-tDV, 0.98 (0.89-0.99) and 0.97 (0.83-0.99) for median and mean gADC respectively, 0.64 (0.25-0.88) for gADC variance, 0.85 (0.57-0.95) for gADC skewness and 0.85 (0.57-0.95) for gADC kurtosis. Further investigation of two anomalous patient cases revealed that a very small proportion of voxels with outlying gADC values lead to instability in higher order gADC statistics. We therefore conclude that estimates of median/mean gADC and tumour volume demonstrate excellent inter- and intra-observer repeatability whilst higher order statistics of gADC should be used with caution when ascribing significance to clinical changes.

Quantification of metabolic tumor activity and burden in patients with non-small-cell lung cancer: Is manual adjustment of semiautomatic gradient-based measurements necessary?

PURPOSE

Metabolic tumor burden (MTB) measurements including metabolic tumor volume and total lesion glycolysis have been shown to have prognostic value in non-small-cell lung cancer (NSCLC). The calculation of MTB typically utilizes software to semiautomatically draw volumes of interest around the tumor, which are subsequently manually adjusted by the radiologist to include the entire tumor. The manual adjustment step can be time-consuming and observer-dependent. We compared the agreement of MTB values obtained using the semiautomatic method with and without manual adjustment in NSCLC patients.

METHODS

This IRB-approved prospective study included 134 patients with histologically proven NSCLC who underwent fluorine-18 fluorodeoxyglucose PET/computed tomography. The MTB of the primary tumor was measured with a semiautomatic gradient-based method without manual adjustment (the semiautomatic gradient method) and with manual adjustment (the manually adjusted semiautomatic gradient method) by two radiologists using the MIM PETedge tool. The paired t-test, Wilcoxon signed-rank test, and concordance correlation coefficient (CCC) were calculated to evaluate the agreement between MTB measures obtained with these two methods, as well as agreement between the two radiologists for each method.

RESULTS

Maximum standardized uptake value was identical between the two methods. No statistically significant difference was present for peak standardized uptake value, metabolic tumor volume, and total lesion glycolysis values between the two methods (P=0.23, 0.45, and 0.37, respectively). Excellent agreement between the two methods was found in terms of CCC (CCC>0.98 for all measures). Interobserver reliability was excellent for all measures (CCC>0.90).

CONCLUSION

The semiautomatic gradient-based tumor-segmentation method can be used without the additional manual adjustment step for MTB quantification of primary NSCLC tumors.

Negative signals for adenomyomatosis of the gallbladder upon diffusion-weighted whole body imaging with background body signal suppression/T2-weighted image fusion analysis

Differentiation between adenomyomatosis (ADM) and cancer of the gallbladder is necessary during diagnosis. Diffusion-weighted whole body imaging with background body signal suppression (DWIBS) images are able to indicate cancer and inflammation. The fusion of a DWIBS with a T2 weighted image (DWIBS/T2) facilitates both functional and anatomical investigations. In the present study, patient records and images from patients with surgically confirmed ADM from April 2012 to October 2014 were analyzed retrospectively. The enrolled patients, including 6 men (64.2±13.1 years) and 4 women (57.3±12.4 years) were subjected to DWIBS/T2 during routine clinical practice. The diagnosis of ADM was based on magnetic resonance cholangiopancreatography, transabdominal ultrasonography, and endoscopic ultrasonography; ADM was diagnosed definitively when cystic lesions were observed, indicating the Rokitansky-Aschoff sinus. A single patient was indicated to be positive by DWIBS/T2 imaging. The Rokitansky-Aschoff sinus revealed a relatively high signal intensity; however, it was not as strong as that of the spleen. The signal intensity was also high on an apparent diffusion coefficient map, suggesting T2 shine-through. The thickened wall displayed low signal intensity. The aforementioned results indicate that ADM may be negative upon DWIBS/T2 imaging; one false positive case was determined to be ADM, accompanied by chronic cholecystitis. The majority of patients with ADM displayed negative findings upon DWIBS/T2 imaging, and chronic cholecystitis may cause false positives.

Chest magnetic resonance imaging: a protocol suggestion

In the recent years, with the development of ultrafast sequences, magnetic resonance imaging (MRI) has been established as a valuable diagnostic modality in body imaging. Because of improvements in speed and image quality, MRI is now ready for routine clinical use also in the study of pulmonary diseases. The main advantage of MRI of the lungs is its unique combination of morphological and functional assessment in a single imaging session. In this article, the authors review most technical aspects and suggest a protocol for performing chest MRI. The authors also describe the three major clinical indications for MRI of the lungs: staging of lung tumors; evaluation of pulmonary vascular diseases; and investigation of pulmonary abnormalities in patients who should not be exposed to radiation.

Role of WB-MR/DWIBS compared to (18)F-FDG PET/CT in the therapy response assessment of lymphoma

INTRODUCTION

This study prospectively evaluated whole-body magnetic resonance/diffusion-weighted imaging with body signal suppression (WB-MR/DWIBS) reliability compared to (18)F-FDG PET/CT in the treatment response assessment of classic Hodgkin lymphomas (HL) and aggressive non-Hodgkin lymphomas (aNHL).

MATERIALS AND METHODS

Twenty-seven consecutive patients were prospectively enrolled at the time of diagnosis. Eighteen (11 HL and seven aNHL) were considered for the analysis. They received chemo/radiotherapy as induction and completed post-treatment evaluation performing both (18)F-FDG PET/CT and WB-MR/DWIBS. The revised response criteria for malignant lymphomas were used to assess the response to treatment. We evaluated the agreement between the two methods by Cohen's K test. Post-therapy WB-MR/DWIBS sensitivity, specificity, PPV, NPV and accuracy were then calculated, considering the 12 months of follow-up period as the gold standard.

RESULTS

By using an evaluation on a lesion-by-lesion basis, WB-MR/DWIBS and (18)F-FDG PET/CT showed an overall good agreement (K = 0.796, 95% IC = 0.651-0.941), especially in the evaluation of the nodal basins in aNHL (K = 0.937, 95% IC = 0.814-1). In reference to the revised response criteria for malignant lymphomas, the two methods showed a good agreement (K = 0.824, 95% IC = 0.493-1). Post-therapy sensitivity, specificity, PPV, NPV and accuracy of WB-MR/DWIBS were 43, 91, 75, 71 and 72%, respectively.

CONCLUSION

WB-MR/DWIBS seems to be an appropriate method for the post-treatment assessment of patients affected by HL and aNHL. The small discrepancies between the two methods found within HL could be due to the biological and metabolic behavior of this group of diseases. Larger prospective studies are necessary to better define the role of WB-MR/DWIBS in this setting of patients.

Beyond whole-body imaging: advanced imaging techniques of PET/MRI

PET/MRI is a hybrid imaging modality that is gaining clinical interest with the first Food and Drug Administration-approved simultaneous imaging system recently added to the clinical armamentarium. Several advanced PET/MRI applications, such as high-resolution anatomic imaging, diffusion-weighted imaging, motion correction, and cardiac imaging, show great potential for clinical use. The purpose of this article is to highlight several advanced PET/MRI applications through case examples and review of the current literature.

Magnetic resonance colonography including diffusion-weighted imaging in children and adolescents with inflammatory bowel disease: do we really need intravenous contrast?

OBJECTIVES

Magnetic resonance colonography (MRC) is a well-accepted, noninvasive imaging modality for the depiction of inflammatory bowel disease. Diffusion-weighted imaging (DWI) is very helpful to display inflammatory lesions. The aim of this retrospective study was to assess whether intravenous contrast is needed to depict inflammatory lesions in bowel magnetic resonance imaging if DWI is available.

MATERIALS AND METHODS

Thirty-seven patients (23 females, 14 males; mean age, 14.6 years) underwent MRC on a 1.5-T scanner (MAGNETOM Avanto; Siemens). Contrast-enhanced T1-weighted (ce-T1-w) sequences and DWI sequences in axial and coronal planes (b = 50, 500, 1000) were acquired. Two reviewers evaluated (1) DWI, (2) ce-T1-w MRC, as well as (3) DWI and ce-T1-w MRC concerning lesion conspicuity. The preferred b value was assessed. Colonoscopy was performed within 1 week, including biopsies serving as the reference standard. Sensitivities and specificities were calculated, and interobserver variability was assessed.

RESULTS

Mean sensitivity and specificity of the 2 readers for the depiction of inflammatory lesions were 78.4%/100% using ce-T1-w MRC, 95.2%/100% using DWI, and 93.5%/100% combining both imaging techniques compared with colonoscopy including results of the histopathological samples. In 6 patients, inflammatory lesions were only detected by DWI; in another 6 patients, DWI detected additional lesions. The κ values for the 2 readers were excellent (k = 0.92-0.96). The preferred b value with the best detectability of the lesion was b1000 in 28 of the 30 patients (93.3%) with restricted diffusion.

CONCLUSIONS

Diffusion-weighted imaging of the bowel identified inflammatory lesions with high accuracy and revealed lesions that were not detectable with ce-T1-w imaging alone. A b value of 1000 showed the best lesion detectability.

Image-guided surgery using multimodality strategy and molecular probes

The ultimate goal of cancer surgery is to maximize the excision of tumorous tissue with minimal damage to the collateral normal tissues, reduce the postoperative recurrence, and improve the survival rate of patients. In order to locate tumor lesions, highlight tumor margins, visualize residual disease in the surgical wound, and map potential lymph node metastasis, various imaging techniques and molecular probes have been investigated to assist surgeons to perform more complete tumor resection. Combining imaging techniques with molecular probes is particularly promising as a new approach for image-guided surgery. Considering inherent limitations of different imaging techniques and insufficient sensitivity of nonspecific molecular probes, image-guided surgery with multimodality strategy and specific molecular probes appears to be an optimal choice. In this article, we briefly describe typical imaging techniques and molecular probes followed by a focused review on the current progress of multimodal image-guided surgery with specific molecular navigation. We also discuss optimal strategy that covers all stages of image-guided surgery including preoperative scanning of tumors, intraoperative inspection of surgical bed and postoperative care of patients.

Update and current status of diffusion-weighted MRI in anorectal malignancy

SUMMARY 

Diffusion-weighted imaging (DWI) is an MRI technique that yields unique information regarding the movement of water molecules at the cellular level. Now widely available and rapid to perform the sequence is increasingly utilized within abdominopelvic oncology, including anorectal cancer imaging. Unfortunately, the diffusion properties of anorectal tumors are complex and not fully understood, with areas of cellular tumor, necrosis and fibrosis co-existing. While DWI shows promise both for staging and in assessing treatment response in anorectal cancer, there remains a lack of consensus regarding its role and integration into standard MRI protocols. This article outlines the basic science behind DWI and reviews the current evidence base for its use in anorectal cancer.

Preliminary comparison of diffusion-weighted MRI and PET/CT in predicting histological type and malignancy of lung cancer

INTRODUCTION

Emerging evidence shows that diffusion-weighted magnetic resonance imaging (DW MRI) and fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸ F-FDG PET/CT) might be useful in predicting histological type and malignancy of lung cancer, and even in specifically detecting the types of gene mutation.

OBJECTIVE

We assessed whether DW MRI is equivalent to PET/CT in lung cancer diagnosis and evaluation.

METHODS

The institutional review board approved this study, and written informed consent was obtained from all patients. DW MRI and FDG PET/CT were performed before therapy in 15 lung cancer patients diagnosed by pathological examination. Apparent diffusion coefficient (ADC), ratio of ADC (rADC = ADC in tumor/ADC in spinal cord) and maximal standardized uptake value (SUV_max ) were assessed.

RESULTS

ADC, rADC and SUV_max did not reveal significant differences among different types of lung cancer. Sensitivity, specificity and accuracy of ADC, rADC and SUV_max proved to be not significantly different in the detection of adenocarcinoma and squamous cell carcinoma. Difference in the abilities of the sensitivity, specificity and accuracy of ADC, rADC and SUV_max to detect adenocarcinoma and squamous cell carcinoma proved to be insignificant. Although Ki-67 score did not show correlation with ADC, rADC and SUV_max , significant positive correlation was found between ADC and rADC, and ADC and SUV_max .

CONCLUSIONS

Both DW MRI and FDG PET/CT had similar limited diagnostic capability of predicting different histological types and malignancy of lung cancer. This study may help provide a novel insight into diagnostic and therapeutic strategies of lung cancer based on DW MRI.

Apparent diffusion coefficient values of diffusion-weighted imaging for distinguishing focal pulmonary lesions and characterizing the subtype of lung cancer: a meta-analysis

OBJECTIVES

The potential performance of apparent diffusion coefficient (ADC) values for distinguishing malignant and benign pulmonary lesions, further characterizing the subtype of lung cancer was assessed.

METHODS

PubMed, EMBASE, Cochrane Library, EBSCO, and three Chinese databases were searched to identify eligible studies on diffusion-weighted imaging (DWI) of focal pulmonary lesions. ADC values of malignant and benign lesions were extracted by lesion type and statistically pooled based on a linear mixed model. Further analysis for subtype of lung cancer was also performed. The methodological quality was assessed using the quality assessment of diagnostic accuracy studies tool.

RESULTS

Thirty-four articles involving 2086 patients were included. Malignant pulmonary lesions have significantly lower ADC values than benign lesions [1.21 (95% CI, 1.19-1.22) mm(2)/s vs. 1.76 (95% CI, 1.72-1.80) mm(2)/s; P < 0.05]. There is a significant difference between ADC values of small cell lung cancer and non-small cell lung cancer (P < 0.05), while the differences were not significant among histological subtypes of lung cancer. The methodological quality was relatively high, and the data points from Begg's test indicated that there was probably no obvious publication bias.

CONCLUSIONS

The ADC value is helpful for distinguishing malignant and benign pulmonary lesions and provides a promising method for differentiation of SCLC from NSCLC.

KEY POINTS

• This meta-analysis assesses the role of DWI in pulmonary lesions. • Differentiation and classification subtype of lung cancer is essential for treatment decision-making. • ADC values can help distinguish between malignant and benign lesions. • ADC values might help characterize the subtype of lung cancer.

Staging of lung cancer

Primary lung cancer is the leading cause of cancer mortality in the world. Thorough clinical staging of patients with lung cancer is important, because therapeutic options and management are to a considerable degree dependent on stage at presentation. Radiologic imaging is an essential component of clinical staging, including chest radiography in some cases, computed tomography, MRI, and PET. Multiplanar imaging modalities allow assessment of features that are important for surgical, oncologic, and radiation therapy planning, including size of the primary tumor, location and relationship to normal anatomic structures in the thorax, and existence of nodal and/or metastatic disease.

Computed diffusion-weighted MRI for prostate cancer detection: the influence of the combinations of b-values

OBJECTIVE

To evaluate the influence of the combinations of b-values on computed diffusion-weighted images (cDWIs) for prostate cancer (PCa) detection at b = 2000 s mm(-2).

METHODS

Diffusion-weighted imaging (DWIs) for 31 patients with PCa (65.2 ± 7.1 years) were obtained pre-operatively at different b-values (0, 100, 500, 1000 and 2000 s mm(-2)) on a 3-T MRI. cDWIs at b = 2000 were generated by using six b-value combinations: 0-100 s mm(-2) (cDWI0-100); 0-500 s mm(-2) (cDWI0-500); 100-500 s mm(-2) (cDWI100-500); 0-1000 s mm(-2) (cDWI0-1000); 100-1000 s mm(-2) (cDWI100-1000); and 500-1000 s mm(-2) (cDWI500-1000). These cDWIs and measured DWIs with b = 2000 s mm(-2) (mDWI2000) were evaluated in this setting. To assess image quality for each DWI, contrast ratios (CRs) of cancerous and non-cancerous lesions were evaluated. To compare the detectability of PCa for each DWI, receiver operating characteristic analysis was used.

RESULTS

CRs of all cDWIs were significantly higher than those of mDWI2000 (p < 0.05). Areas under the curve of cDWI0-100 (0.62) and cDWI0-500 (0.65) were significantly smaller (p < 0.05) than those of others (cDWI100-500, 0.72; cDWI0-1000, 0.73; cDWI100-1000, 0.71; cDWI500-1000, 0.74; mDWI2000, 0.72).

CONCLUSION

The combinations of b-values influenced image quality and diagnostic ability of cDWIs for PCa detection. The combinations of b ≥ 100 and b ≥ 500 s mm(-2), as well as b = 0 and b = 1000 s mm(-2), were optimal in this study.

ADVANCES IN KNOWLEDGE

For generating the useful cDWI for PCa detection, radiologists should take care of the combination of b-values when including low b-values.

Three-way Comparison of Whole-Body MR, Coregistered Whole-Body FDG PET/MR, and Integrated Whole-Body FDG PET/CT Imaging: TNM and Stage Assessment Capability for Non-Small Cell Lung Cancer Patients

PURPOSE

To prospectively compare the capabilities for TNM classification and assessment of clinical stage and operability among whole-body magnetic resonance (MR) imaging, coregistered positron emission tomographic (PET)/MR imaging with and without MR signal intensity (SI) assessment, and integrated fluorine 18 fluorodeoxyglucose (FDG) PET/computed tomography (CT) in non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

The institutional review board approved this study, and written informed consent was obtained from each patient. One hundred forty consecutive NSCLC patients (75 men, 65 women; mean age, 72 years) prospectively underwent whole-body MR imaging, FDG PET/CT, conventional radiologic examinations, and surgical, pathologic, and/or follow-up examinations. All factors and clinical stage and operability were then visually assessed. All PET/MR examinations were assessed with and without SI assessment. One examination used anatomic, metabolic, and relaxation-time information, and the other used only anatomic and metabolic information. κ statistics were used for assessment of all factors and clinical stages with final diagnoses. McNemar test was used to compare the capability of all methods to assess operability.

RESULTS

Agreements of assessment of every factor (κ = 0.63-0.97) and clinical stage (κ = 0.65-0.90) were substantial or almost perfect. Regarding capability to assess operability, accuracy of whole-body MR imaging and PET/MR imaging with SI assessment (97.1% [136 of 140]) was significantly higher than that of MR/PET without SI assessment and integrated FDG PET/CT (85.0% [119 of 140]; P < .001).

CONCLUSION

Accuracies of whole-body MR imaging and PET/MR imaging with SI assessment are superior to PET/MR without SI assessment and PET/CT for identification of TNM factor, clinical stage, and operability evaluation of NSCLC patients.

Role of imaging in diagnosis, staging and follow-up of lung cancer

PURPOSE OF REVIEW

Primary lung cancer is still the number one cause of cancer death worldwide. Screening, detection and staging of lung cancer are important because the only potentially curative therapy today is surgical resection of early-stage lung cancer.

RECENT FINDINGS

Different imaging techniques can be used in these different processes. Recent advances in computed tomography (CT) technology have allowed investigation of novel methods for the evaluation of lung cancer. Recent advances in magnetic resonance technology and administration of contrast media have further improved the image quality and diagnostic capability of magnetic resonance. Positron emission tomography (PET)/CT has been shown to be superior to stand-alone PET or CT in the evaluation of lymph nodes and in the detection of distant metastases.

SUMMARY

The current recommended imaging required for lung cancer staging is CT of the thorax and PET/CT from skull base to mid-thigh. However, with the recent developments in the armamentarium of imaging techniques, the choice of one of these techniques can be directed by the presence of a technique in a local hospital and/or by the presence of an experienced person at that time.

Integrated whole body MR/PET: where are we?

Whole body integrated magnetic resonance imaging (MR)/positron emission tomography (PET) imaging systems have recently become available for clinical use and are currently being used to explore whether the combined anatomic and functional capabilities of MR imaging and the metabolic information of PET provide new insight into disease phenotypes and biology, and provide a better assessment of oncologic diseases at a lower radiation dose than a CT. This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions. Various early clinical applications of integrated MR/PET are also addressed. Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.

Magnetic resonance imaging for lung cancer screen

Lung cancer is the leading cause of cancer related death throughout the world. Lung cancer is an example of a disease for which a large percentage of the high-risk population can be easily identified via a smoking history. This has led to the investigation of lung cancer screening with low-dose helical/multi-detector CT. Evidences suggest that early detection of lung cancer allow more timely therapeutic intervention and thus a more favorable prognosis for the patient. The positive relationship of lesion size to likelihood of malignancy has been demonstrated previously, at least 99% of all nodules 4 mm or smaller are benign, while noncalcified nodules larger than 8 mm diameter bear a substantial risk of malignancy. In the recent years, the availability of high-performance gradient systems, in conjunction with phased-array receiver coils and optimized imaging sequences, has made MR imaging of the lung feasible. It can now be assumed a threshold size of 3-4 mm for detection of lung nodules with MRI under the optimal conditions of successful breath-holds with reliable gating or triggering. In these conditions, 90% of all 3-mm nodules can be correctly diagnosed and that nodules 5 mm and larger are detected with 100% sensitivity. Parallel imaging can significantly shorten the imaging acquisition time by utilizing the diversity of sensitivity profile of individual coil elements in multi-channel radiofrequency receive coil arrays or transmit/receive coil arrays to reduce the number of phase encoding steps required in imaging procedure. Compressed sensing technique accelerates imaging acquisition from dramatically undersampled data set by exploiting the sparsity of the images in an appropriate transform domain. With the combined imaging algorithm of parallel imaging and compressed sensing and advanced 32-channel or 64-channel RF hardware, overall imaging acceleration of 20 folds or higher can then be expected, ultimately achieve free-breathing and no ECG gating acquisitions in lung cancer MRI screening. Further development of protocols, more clinical trials and the use of advanced analysis tools will further evaluate the real significance of lung MRI.

Multimodality molecular imaging of the lung

Lung diseases cause significant morbidity and mortality and lead to high healthcare utilization. However, few lung disease-specific biomarkers are available to accurately monitor disease activity for the purposes of clinical management or drug development. Advances in cross-modal imaging technologies, such as combined positron emission tomography (PET) and magnetic resonance (MR) imaging scanners and PET or single-photon emission computed tomography (SPECT) combined with computed tomography (CT), may aid in the development of noninvasive, molecular-based biomarkers for lung disease. However, the lungs pose particular challenges in obtaining accurate quantification of imaging data due to the low density of the organ and breathing motion. This review covers the basic physics underlying PET, SPECT, CT, and MR lung imaging and presents technical considerations for multimodal imaging with regard to PET and SPECT quantification. It also includes a brief review of the current and potential clinical applications for these hybrid imaging technologies.

Non-contrast-enhanced whole-body magnetic resonance imaging in the general population: the incidence of abnormal findings in patients 50 years old and younger compared to older subjects

Purpose

To assess and compare the incidence of abnormal findings detected during non-contrast-enhanced whole-body magnetic resonance imaging (WB-MRI) in the general population in two age groups: (1) 50 years old and younger; and (2) over 50 years old.

Materials and Methods

The analysis included 666 non-contrast-enhanced WB-MRIs performed on a 1.5-T scanner between December 2009 and June 2013 in a private hospital in 451 patients 50 years old and younger and 215 patients over 50 years old. The following images were obtained: T2-STIR (whole body-coronal plane), T2-STIR (whole spine-sagittal), T2-TSE with fat-saturation (neck and trunk-axial), T2-FLAIR (head-axial), 3D T1-GRE (thorax-coronal, axial), T2-TSE (abdomen-axial), chemical shift (abdomen-axial). Detected abnormalities were classified as: insignificant (type I), potentially significant, requiring medical attention (type II), significant, requiring treatment (type III).

Results

There were 3375 incidental findings depicted in 659 (98.9%) subjects: 2997 type I lesions (88.8%), 363 type II lesions (10.8%) and 15 type III lesions (0.4%), including malignant or possibly malignant lesions in seven subjects. The most differences in the prevalence of abnormalities on WB-MRI between patients 50 years old and younger and over 50 years old concerned: brain infarction (22.2%, 45.0% respectively), thyroid cysts/nodules (8.7%, 18.8%), pulmonary nodules (5.0%, 16.2%), significant degenerative disease of the spine (23.3%, 44.5%), extra-spinal degenerative disease (22.4%, 61.1%), hepatic steatosis (15.8%, 24.9%), liver cysts/hemangiomas (24%, 34.5%), renal cysts (16.9%, 40.6%), prostate enlargement (5.1% of males, 34.2% of males), uterine fibroids (16.3% of females, 37.9% of females).

Conclusions

Incidental findings were detected in almost all of the subjects. WB-MRI demonstrated that the prevalence of the vast majority of abnormalities increases with age.

Meta-analysis of diagnosis of liver metastatic cancers: comparison of (18) FDG PET-CT and gadolinium-enhanced MRI

INTRODUCTION

We performed a meta-analysis to compare the performance of 18F-fluorodeoxyglucose ((18) FDG) positron emission tomography-CT (PET-CT) with that of gadolinium-enhanced MRI for the detection of liver metastatic cancers.

METHODS

The MEDLINE and EMBASE databases were searched for relevant original articles. The histology and/or imaging follow-up data served as the reference standard. We calculated the pooled sensitivities, specificities, positive likelihood ratios, negative likelihood ratios and constructed summary receiver operating characteristic curves for (18) FDG PET-CT and gadolinium-enhanced MRI, respectively.

RESULTS

Ten studies (1105 patients) were included for this meta-analysis. (18) FDG PET-CT has similar patient-based specificity (1.00 and 0.99), positive likelihood ratios (253.1 and 138.2), negative likelihood ratios (0.16 and 0.10) and area under curves (0.99 and 0.99) with gadolinium-enhanced MRI. Gadolinium-enhanced MRI tends to have higher sensitivity (0.91 and 0.84) than (18) FDG PET-CT.

CONCLUSION

Both (18) FDG PET-CT and gadolinium-enhanced MRI have excellent diagnostic performance for the detection of liver metastatic cancer.

Diagnostic accuracy of whole-body PET/MRI and whole-body PET/CT for TNM staging in oncology

PURPOSE

In various tumours PET/CT with [(18)F]FDG is widely accepted as the diagnostic standard of care. The purpose of this study was to compare a dedicated [(18)F]FDG PET/MRI protocol with [(18)F]FDG PET/CT for TNM staging in a cohort of oncological patients.

METHODS

A dedicated [(18)F]FDG PET/MRI protocol was performed in 73 consecutive patients (mean age of 59 years, range 21 - 85 years) with different histologically confirmed solid primary malignant tumours after a routine clinical FDG PET/CT scan (60 min after injection of 295 ± 45 MBq [(18)F]FDG). TNM staging according to the 7th edition of the AJCC Cancer Staging Manual was performed by two readers in separate sessions for PET/CT and PET/MRI images. Assessment of the primary tumour and nodal and distant metastases with FDG PET/CT and FDG PET/MRI was based on qualitative and quantitative analyses. Histopathology, and radiological and clinical follow-up served as the standards of reference. A McNemar test was performed to evaluate the differences in diagnostic performance between the imaging procedures.

RESULTS

From FDG PET/CT and FDG PET/MRI T stage was correctly determined in 22 (82 %) and 20 (74 %) of 27 patients, N stage in 55 (82 %) and 56 (84 %) of 67 patients, and M stage in 32 (76 %) and 35 (83 %) of 42 patients, respectively. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for lymph node metastases were 65 %, 94 %, 79 %, 89 % and 87 % for PET/CT, and 63 %, 94 %, 80 %, 87 % and 85 % for PET/MRI. The respective values for the detection of distant metastases were 50 %, 82 %, 40 %, 88 % and 76 % for PET/CT, and 50 %, 91 %, 57 %, 89 % and 83 % for PET/MRI. Differences between the two imaging modalities were not statistically significant (P > 0.05).

CONCLUSION

According to our results, FDG PET/CT and FDG PET/MRI are of equal diagnostic accuracy for TNM staging in patients with solid tumours.

Modern diagnostic and therapeutic interventional radiology in lung cancer

Imaging has an important role in the multidisciplinary management of primary lung cancer. This article reviews the current state-of-the-art imaging modalities used for the evaluation, staging and post-treatment follow-up and surveillance of lung cancers, and image-guided percutaneous techniques for biopsy to confirm the diagnosis and for local therapy in non-surgical candidates.

Prognostic value of metabolic tumor burden in lung cancer

Accurate prognosis in patients with lung cancer is important for clinical decision making and treatment selection. The TNM staging system is currently the main method for establishing prognosis. Using this system, patients are grouped into one of four stages based on primary tumor extent, nodal disease, and distant metastases. However, each stage represents a range of disease extent and may not on its own be the best reflection of individual patient prognosis. (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) can be used to evaluate the metabolic tumor burden affecting the whole body with measures such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG). MTV and TLG have been shown to be significant prognostic factors in patients with lung cancer, independent of TNM stage. These metabolic tumor burden measures have the potential to make lung cancer staging and prognostication more accurate and quantitative, with the goal of optimizing treatment choices and outcome predictions.

Lung cancer imaging

Lung cancer remains the leading cause of cancer-related deaths in the US. Imaging plays an important role in the diagnosis, staging, and follow-up evaluation of patients with lung cancer. With recent advances in technology, it is important to update and standardize the radiological practices in lung cancer evaluation. In this article, the authors review the main clinical applications of different imaging modalities and the most common radiological presentations of lung cancer.

Assessment of treatment response by total tumor volume and global apparent diffusion coefficient using diffusion-weighted MRI in patients with metastatic bone disease: a feasibility study

We describe our semi-automatic segmentation of whole-body diffusion-weighted MRI (WBDWI) using a Markov random field (MRF) model to derive tumor total diffusion volume (tDV) and associated global apparent diffusion coefficient (gADC); and demonstrate the feasibility of using these indices for assessing tumor burden and response to treatment in patients with bone metastases. WBDWI was performed on eleven patients diagnosed with bone metastases from breast and prostate cancers before and after anti-cancer therapies. Semi-automatic segmentation incorporating a MRF model was performed in all patients below the C4 vertebra by an experienced radiologist with over eight years of clinical experience in body DWI. Changes in tDV and gADC distributions were compared with overall response determined by all imaging, tumor markers and clinical findings at serial follow up. The segmentation technique was possible in all patients although erroneous volumes of interest were generated in one patient because of poor fat suppression in the pelvis, requiring manual correction. Responding patients showed a larger increase in gADC (median change = +0.18, range = -0.07 to +0.78 × 10(-3) mm2/s) after treatment compared to non-responding patients (median change = -0.02, range = -0.10 to +0.05 × 10(-3) mm2/s, p = 0.05, Mann-Whitney test), whereas non-responding patients showed a significantly larger increase in tDV (median change = +26%, range = +3 to +284%) compared to responding patients (median change = -50%, range = -85 to +27%, p = 0.02, Mann-Whitney test). Semi-automatic segmentation of WBDWI is feasible for metastatic bone disease in this pilot cohort of 11 patients, and could be used to quantify tumor total diffusion volume and median global ADC for assessing response to treatment.

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

OBJECTIVES

To 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 (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) and chest-CT.

METHODS

Thirty-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).

RESULTS

Two 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 (18)F-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 (18)F-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.

CONCLUSIONS

Our 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 (18)F-FDG-PET/CT, especially in the detection of non (18)F-FDG avid second primary tumors.

Molecular imaging for cancer diagnosis and surgery

Novel molecular imaging techniques have the potential to significantly enhance the diagnostic and therapeutic approaches for cancer treatment. For solid tumors in particular, novel molecular enhancers for imaging modalities such as US, CT, MRI and PET may facilitate earlier and more accurate diagnosis and staging which are prerequisites for successful surgical therapy. Enzymatically activatable "smart" molecular MRI probes seem particularly promising because of their potential to image tumors before and after surgical removal without re-administration of the probe to evaluate completeness of surgical resection. Furthermore, the use of "smart" MR probes as part of screening programs may enable detection of small tumors throughout the body in at-risk patient populations. Dual labeling of molecular MR probes with fluorescent dyes can add real time intraoperative guidance facilitating complete tumor resection and preservation of important structures. A truly theranostic approach with the further addition of therapeutic agents to the molecular probe for adjuvant therapy is conceivable for the future.

Advanced imaging (positron emission tomography and magnetic resonance imaging) and image-guided biopsy in initial staging and monitoring of therapy of lung cancer

The results of the National Lung Screening Trial strongly support early detection and definitive treatment to reduce lung cancer mortality. Once lung cancer is discovered, accurate staging at baseline is imperative to maximize patient benefit and cost-effective use of health care resources. Although computed tomography (CT) remains a powerful tool for staging of lung cancer, advances in other imaging modalities, specifically positron emission tomography/CT and magnetic resonance imaging, can improve baseline staging over CT alone and can allow a more rapid and accurate assessment of response to treatment. Although noninvasive imaging is extremely useful, tissue diagnosis remains the criterion standard for staging lung cancer and monitoring treatment response. Accordingly, tissue sampling using advanced bronchoscopic imaging guidance, such as ultrasound or electromagnetic navigation, allows precise tissue location and sampling of mediastinal nodes or lung nodules in the least invasive manner. In the future, bronchoscopy may allow real-time microscopic analysis.

Diagnostic value of whole-body diffusion-weighted magnetic resonance imaging for detection of primary and metastatic malignancies: a meta-analysis

PURPOSE

To perform a meta-analysis to evaluate the diagnostic performance of whole-body diffusion-weighted magnetic resonance imaging (WB-DWI) technique in detection of primary and metastatic malignancies compared with that of whole-body positron emission tomography/computed tomography (WB-PET/CT).

MATERIALS AND METHODS

Search Pubmed, MEDLINE, EMBASE and Cochrane Library database from January 1984 to July 2013 for studies comparing WB-DWI with WB-PET/CT for detection of primary and metastatic malignancies. Methodological quality was assessed by the quality assessment of diagnostic studies (QUADAS) instrument. Sensitivities, specificities, predictive values, diagnostic odds ratio (DOR) and areas under the summary receiver operator characteristic curve (AUC) were calculated. Potential threshold effect, heterogeneity and publication bias were investigated.

RESULT

Thirteen eligible studies were included, with a total of 1067 patients. There was no significant threshold effect. WB-DWI had a similar AUC (0.966 (95% CI, 0.940-0.992) versus 0.984 (95% CI, 0.965-0.999)) with WB-PET/CT. No significant difference was detected between AUC of WB-DWI and WB-PET/CT. WB-DWI had a pooled sensitivity of 0.897 (95% CI, 0.876-0.916) and a pooled specificity of 0.954 (95% CI, 0.944-0.962). WB-PET/CT had a pooled sensitivity of 0.895 (95% CI, 0.865-0.920) and a pooled specificity of 0.975 (95% CI, 0.966-0.981). Heterogeneity was found to stem primarily from data type (per lesion versus per patient), MR sequence (DWIBS only and DWIBS with other sequence), and primary lesion type (single type and multiple type). The Deeks's funnel plots suggested the absence of publication bias.

CONCLUSION

WB-DWI has similar, good diagnostic performance for the detection of primary and metastatic malignancies compared with WB-PET/CT. DWIBS with other MR sequences could further improve the diagnostic performance. More high-quality studies regarding comparison of WB-DWI and WB-PET/CT and combination of them in detecting malignancies are still needed to be conducted.

Accuracy of diffusion-weighted (DW) MRI with background signal suppression (MR-DWIBS) in diagnosis of mediastinal lymph node metastasis of nonsmall-cell lung cancer (NSCLC)

PURPOSE

To prospectively evaluate the accuracy of diffusion-weighted (DW) magnetic resonance (MR) imaging with background signal suppression (MR-DWIBS) for detecting mediastinal lymph node metastasis of nonsmall-cell lung cancer (NSCLC).

MATERIALS AND METHODS

MR-DWIBS was performed in 42 consecutive patients (27 men, 15 women; age range, 42-78 years; median age, 55 years) with histologically proven NSCLC. The visualization rate of metastatic lymph node (MLN) and benign lymph node (BLN) of enlarged lymph nodes (ELN) and normal-sized lymph nodes (NLN) was compared by using a chi-square test or Fisher's exact test on a per-nodal basis. Apparent diffusion coefficient (ADC) of MLN and BLN was measured and compared by using two-tailed unpaired Student's t-test. Receiver operating characteristic (ROC) analysis was used to assess the overall diagnostic accuracy of ADC for ELN and NLN. The optimal cutoff value was determined and the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy was calculated.

RESULTS

Thirty-five out of 119 lymph resected nodes were confirmed to be metastatic by histologic examination. The visualization rate of MLN was significantly higher than that of BLN for ELN (P < 0.001) and for NLN (χ(2) = 7.506, P = 0.006). For both ELN and NLN, ADC of MLN was significantly lower than that of BLN (t = -5.380, P < 0.001 and t = -6.435, P < 0.001). ADC was significant for detection of MLN for both ELN (Az = 0.975, P < 0.001) and NLN (Az = 0.919, P < 0.001). For NLN, the optimal cutoff value of ADC was 2.04 mm(2)/s, where the sensitivity, specificity, PPV, NPV, and accuracy were 75.0%, 90.9%, 66.7%, 93.8%, and 87.8%, respectively.

CONCLUSION

MR-DWIBS may be clinically useful to visually detect mediastinal lymph nodes and ADC measurement can aid in malignant node discrimination.

Improved short tau inversion recovery (iSTIR) for increased tumor conspicuity in the abdomen

OBJECT

To develop an improved short tau inversion recovery (iSTIR) technique with simultaneous suppression of fat, blood vessels and fluid to increase tumor conspicuity in the abdomen for cancer screening.

MATERIALS AND METHODS

An adiabatic spectrally selective inversion pulse was used for fat suppression to overcome the reduced signal to noise ratio associated with chemically non-selective inversion pulse of STIR. A motion-sensitizing driven equilibrium was used for blood vessel suppression and a dual-echo single-shot fast spin echo acquisition was used for fluid suppression. The technique was optimized on four normal subjects and later tested on five patients referred for metastatic tumor evaluation.

RESULTS

A velocity encoding of 2 cm/s achieved effective blood suppression even in small vessels. Subtraction of two images (one with 60 ms and the other with 280 ms echo time) acquired in the same echo train achieved excellent fluid suppression (>70% reduction). Simultaneous suppression of fat, blood vessels and fluid improved the tumor conspicuity compared to corresponding fat-suppressed (STIR) image.

CONCLUSION

This technique generated two complementary images from a single scan: one that is equivalent to a STIR image and the other that qualitatively resembles a diffusion-weighted image and may have potential for magnetic resonance imaging cancer screening.

Comparison of FDG PET/CT and gadolinium-enhanced MRI for the detection of bone metastases in patients with cancer: a meta-analysis

OBJECTIVE

At present, the differences in the efficacy between PET/CT and MRI for the detection of bone metastases in patients with cancer have not been clearly delineated. We performed a meta-analysis to compare the performance of FDG PET/CT with that of gadolinium-enhanced MRI for the detection of bone metastases in patients with cancer.

METHODS

Studies about PET/CT and MRI for the detection of bone metastases were systematically searched in the MEDLINE, EMBASE, and EBM Review databases. We calculated sensitivities, specificities, diagnostic odds ratios, positive likelihood ratios, negative likelihood ratios (NLR), and constructed summary receiver operating characteristic curves using bivariate regression models for PET/CT and MRI, respectively.

RESULTS

Across 9 studies (1116 patients), FDG PET/CT has similar patient-based sensitivity (0.803 vs 0.837), specificity (0.989 vs 0.977), diagnostic odds ratio (309.0 vs 221.9), positive likelihood ratio (61.7 vs 37.0), and negative likelihood ratio (0.200 vs 0.167) with gadolinium-enhanced MRI. Areas under the curve with 95% confidence interval for FDG PET/CT and gadolinium-enhanced MRI were 0.99 (0.98-0.99) and 0.98 (0.97-0.99), respectively.

CONCLUSIONS

FDG PET/CT and gadolinium-enhanced MRI have excellent diagnostic performance for the detection of bone metastases in patients with cancer.

DW MRI at 3.0 T versus FDG PET/CT for detection of malignant pulmonary tumors

Emerging evidence suggests that diffusion-weighted magnetic resonance imaging (DW MRI) could be useful for tumor detection with N and M staging of lung cancer in place of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT). DW MRI at 3.0 T and FDG PET/CT were performed before therapy in 113 patients with pulmonary nodules. Mean apparent diffusion coefficient (ADC), maximal standardized uptake value (SUVmax ) and Ki-67 scores were assessed. Quantitatively, specificity and accuracy of ADC (91.7 and 92.9%, respectively) were significantly higher than those of SUVmax (66.7 and 77.9% respectively, p < 0.05), although sensitivity was not significantly different between them (93.5 and 83.1%, p > 0.05). Qualitatively, sensitivity, specificity and accuracy of DW MRI (96.1, 83.3 and 92.0%, respectively) were also not significantly different from that of FDG PET/CT (88.3, 83.3 and 86.7%, respectively, p > 0.05). Significant negative correlation was found between Ki-67 score and ADC (r = -0.66, p < 0.05), ADC and SUVmax (r = -0.37, p < 0.05), but not between Ki-67 score and SUVmax (r = -0.11, p > 0.05). In conclusion, quantitative and qualitative assessments for detection of malignant pulmonary tumors with DW MRI at 3.0 T are superior to those with FDG PET/CT. Furthermore, ADC could predict the malignancy of lung cancer.

Whole body MRI: improved lesion detection and characterization with diffusion weighted techniques

Diffusion-weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole-body MRI. Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole-body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b-values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation.

Comparison between whole-body MRI and Fluorine-18-Fluorodeoxyglucose PET or PET/CT in oncology: a systematic review

BACKGROUND

The aim of the article is to systematically review published data about the comparison between positron emission tomography (PET) or PET/computed tomography (PET/CT) using Fluorine-18-Fluorodeoxyglucose (FDG) and whole-body magnetic resonance imaging (WB-MRI) in patients with different tumours.

METHODS

A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus and Embase databases through April 2012 and regarding the comparison between FDG-PET or PET/CT and WB-MRI in patients with various tumours was carried out.

RESULTS

Forty-four articles comprising 2287 patients were retrieved in full-text version, included and discussed in this systematic review. Several articles evaluated mixed tumours with both diagnostic methods. Concerning the specific tumour types, more evidence exists for lymphomas, bone tumours, head and neck tumours and lung tumours, whereas there is less evidence for other tumour types.

CONCLUSIONS

Overall, based on the literature findings, WB-MRI seems to be a valid alternative method compared to PET/CT in oncology. Further larger prospective studies and in particular cost-effectiveness analysis comparing these two whole-body imaging techniques are needed to better assess the role of WB-MRI compared to FDG-PET or PET/CT in specific tumour types.

Computed diffusion-weighted imaging using 3-T magnetic resonance imaging for prostate cancer diagnosis

OBJECTIVE

To assess the efficacy of computed diffusion-weighted images (cDWIs) of b = 2000 s/mm(2) (cDWI2000) generated from DWIs of b = 0 and 1000 for prostate cancer (PCa) diagnosis in comparison with that of measured original DWIs of b = 1000 (mDWI1000) and b = 2000(mDWI2000) using 3-T MRI.

METHODS

Eighty patients who underwent a preoperative MRI examination, including T2WI and DWI (b = 0, 1000, 2000 s/mm(2)), were enrolled in this study. Four combinations of images, protocol A (T2WI alone), B (T2WI + mDWI1000), C (T2WI + mDWI2000) and D (T2WI + cDWI2000), were assessed for their diagnostic capability. Areas under the receiver operating characteristic curve (Az) and diagnostic performance were evaluated, as well as contrast ratios (CR) between cancerous and non-cancerous lesions for each DWI.

RESULTS

The highest CR was obtained with cDWI2000 (0.29 ± 0.16). Sensitivity, specificity, accuracy, and Az of the protocols were: A: 66.3 %, 59.4 %, 63.0 %, 0.67; B: 82.6 %, 62.0 %, 72.5 %, 0.80; C: 84.1 %, 66.5 %, 75.5 %, 0.86; D: 83.2 %, 70.0 %, 76.6 %, and 0.84, respectively The specificities and accuracies of protocol C and D were significantly higher than those of protocol B (P < 0.05).

CONCLUSION

cDWI2000 appears to be more effective than mDWI1000, and at least as effective as mDWI2000 for PCa diagnosis.