Turbo STIR magnetic resonance imaging as a whole-body screening tool for metastases in patients with breast carcinoma: preliminary clinical experience

Whole-body MRI in oncology: can a single anatomic T2 Dixon sequence replace the combination of T1 and STIR sequences to detect skeletal metastasis and myeloma?

OBJECTIVES

To compare the diagnostic accuracy of a single T2 Dixon sequence to the combination T1+STIR as anatomical sequences used for detecting tumoral bone marrow lesions in whole-body MRI (WB-MRI) examinations.

METHODS

Between January 2019 and January 2020, seventy-two consecutive patients (55 men, 17 women, median age = 66 years) with solid (prostate, breast, neuroendocrine) cancers at high risk of metastasis or proven multiple myeloma (MM) prospectively underwent a WB-MRI examination including coronal T1, STIR, T2 Dixon and axial diffusion-weighted imaging sequences. Two radiologists independently assessed the combination of T1+STIR sequences and the fat+water reconstructions from the T2 Dixon sequence. The reference standard was established by consensus reading of WB-MRI and concurrent imaging available at baseline and at 6 months. Repeatability and reproducibility of MRI scores (presence and semi-quantitative count of lesions), image quality (SNR: signal-to-noise, CNR: contrast-to-noise, CRR: contrast-to-reference ratios), and diagnostic characteristics (Se: sensitivity, Sp: specificity, Acc: accuracy) were assessed per-skeletal region and per-patient.

RESULTS

Repeatability and reproducibility were at least good regardless of the score, region, and protocol (0.67 ≤ AC1 ≤ 0.98). CRR was higher on T2 Dixon fat compared to T1 (p < 0.0001) and on T2 Dixon water compared to STIR (p = 0.0128). In the per-patient analysis, Acc of the T2 Dixon fat+water was higher than that of T1+STIR for the senior reader (Acc = +0.027 [+0.025; +0.029], p < 0.0001) and lower for the junior reader (Acc = -0.029 [-0.031; -0.027], p < 0.0001).

CONCLUSIONS

A single T2 Dixon sequence with fat+water reconstructions offers similar reproducibility and diagnostic accuracy as the recommended combination of T1+STIR sequences and can be used for skeletal screening in oncology, allowing significant time-saving.

KEY POINTS

• Replacement of the standard anatomic T1 + STIR WB-MRI protocol by a single T2 Dixon sequence drastically shortens the examination time without loss of diagnostic accuracy. • A protocol based on fat + water reconstructions from a single T2 Dixon sequence offers similar inter-reader agreement and a higher contrast-to-reference ratio for detecting lesions compared to the standard T1 + STIR protocol. • Differences in the accuracy between the two protocols are marginal (+ 3% in favor of the T2 Dixon with the senior reader; -3% against the T2 Dixon with the junior reader).

Is It Time to Call Time on Bone Marrow Biopsy for Staging Ewing Sarcoma (ES)?

Simple Summary

Ewing sarcoma (ES) is a rare primary bone cancer, usually found in children and adolescents, which can spread to the lungs, other bones and less commonly, the bone marrow. An accurate determination of the disease spread at baseline (staging) is important to establish prognosis, monitor treatment response and help with management decisions. There is no standard of care for staging ES, although the invasive bone marrow biopsy has traditionally been used to establish whether patients have bone marrow infiltration. Imaging techniques, including FDG-PET/CT and whole-body MRI (WB-MRI), have become established in staging other cancers with expanding use for staging ES. A number of studies have validated the accuracy, sensitivity and specificity of these modalities for detecting bone and bone marrow metastases in ES. The main aim of this review was to examine the current literature for the use of FDG-PET/CT and WB-MRI in staging ES to determine whether a bone marrow biopsy is still needed and would influence the management of patients. Hereafter, a new staging algorithm for ES recommends WB-MRI and/or FDG-PET/CT without bone marrow biopsy as the standard of care for staging localised and metastatic ES.

Abstract

Primary malignant bone sarcomas are rare and Ewing sarcoma (ES), along with osteosarcoma, predominates in teenagers and young adults. The well-established multimodality treatment incorporates systemic chemotherapy with local control in the form of surgery, with or without radiation. The presence and extent of metastases at diagnosis remains the most important prognostic factor in determining patient outcome; patients with skeletal metastases or bone marrow infiltration having a significantly worse outcome than those with lung metastases alone. There is, however, no accepted staging algorithm for ES. Large cooperative groups and national guidelines continue to advocate bone marrow biopsy (BMB) for staging but functional imaging techniques, such as 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) with computerised tomography (CT) have been increasingly used for staging cancers and whole-body magnetic resonance imaging (WB-MRI) for staging skeletal metastases. This review outlines the current literature, from which we conclude that BMB is no longer required for the staging of ES as it does not influence the standard of care management. BMB may, however, provide prognostic information and insights into the biology of ES in selected patients on prospective clinical trials.

Breast Cancer Brain Metastasis: The Potential Role of MRI Beyond Current Clinical Applications

PURPOSE

Breast cancer brain metastasis (BCBM) represents a major clinical challenge. Can MRI help in advancements in the management of BCBM? This review discusses MRI developments and the corresponding potential advancements in BCBM management.

METHODS

An exhaustive literature search was undertaken to identify studies which look into the potential of MRI in BCBM management. Seven hundred and eighty-four studies published from September 1984 to May 2020 were identified. Three topics are covered where MRI is not clinically established yet: 1) the prognosis of BCBM; 2) the screening of BC patients for BCBM development, and 3) the assessment of imaging features correlated to BC subtype.

RESULTS

Thirty-six studies were considered eligible for the purposes of this review. On-going progress is made with the identification of different BCBM characteristics and MRI metrics that might be related to prognosis. Progress has been made with the identification of different BCBM characteristics, including BCBM location, degree of edema, white matter disruption, tumor edge sharpness, and temporal muscle thickness. A more accurate prediction of prognosis could lead to more suitable patient management and treatment. The use of MRI in BCBM screening of the high-risk breast cancer population remains a controversial subject. To date, there are no results from clinical trials; however, there is a rising number of relatively small studies that show concern on this subject and support BCBM screening. It is important to oncologists to be able to assess the tumor subtype non-invasively. MRI features, which have shown some correlation with subtype, include the number of tumors, location, and their distribution in the brain. Advanced tools and metrics have been produced to carry out radiological characteristics analysis on MRI images. Assessing MRI features in more detail could provide a more personalized management of patients.

CONCLUSION

Developments in the use of MRI have the potential to improve BCBM management.

Bone Metastases: Mechanisms of the Metastatic Process, Imaging and Therapy

The mechanisms by which tumors metastasize to bone are complex. Upon the successful establishment of metastatic deposits in the skeleton, detection of the disease becomes essential for therapeutic planning. The roles of CT, skeletal scintigraphy, SPECT/CT, MRI, PET/CT and PET/MRI will be reviewed. Therapeutic response criteria specifically designed to evaluate bone metastases (MD Anderson/MDA criteria) can guide image interpretation. Knowledge of therapeutic strategies such as systemic therapy with bisphosphonates or radiopharmaceuticals, radiation therapy, surgery, and percutaneous interventions such as vertebroplasty and radiofrequency ablation can help the radiologist produce reports that will provide maximum benefit to clinicians and patients.

Imaging diagnosis of metastatic breast cancer

Numerous imaging modalities may be used for the staging of women with advanced breast cancer. Although bone scintigraphy and multiplanar-CT are the most frequently used tests, others including PET, MRI and hybrid scans are also utilised, with no specific recommendations of which test should be preferentially used. We review the evidence behind the imaging modalities that characterise metastases in breast cancer and to update the evidence on comparative imaging accuracy.

Whole-body MRI: a powerful alternative to bone scan for bone marrow staging without radiation and gadolinium enhancer

PURPOSE

Whole-body magnetic resonance imaging (WB-MRI) is a radiation-free alternative to the ^99mTc-HDP bone scan (BS) for the detection of bone metastasis. The major drawback is the long examination time and application of gadolinium enhancer. The aim of this study is to analyze (i) the performance of WB-MRI versus the BS and (ii) the diagnostic benefit of gadolinium (WB-MRI + Gd) compared to a non-enhanced protocol (NE WB-MRI).

METHODS AND MATERIALS

1256 eligible WB-MRI scans were analyzed retrospectively with a single inclusion criterion, a clinical 12-month follow-up or a biopsy as ground truth. N = 285 patients received both a WB-MRI and a BS within 12 months. All the patients were imaged with a coronal T1w and a STIR, and n = 528 (42%) received an additional T1w-mDixon with gadoteridol (0.1 mmol Gd-DTPA/kg).

RESULTS

From 1256 eligible patients, n = 884 (70%) had breast cancer as a primary disease, n = 101(8%) prostate cancer, and n = 77(6%) lung cancer. The sensitivity (Se) and negative predictive value (NPV) of the WB-MRI was 98/99%, significantly higher compared to BS with 82/89%, P < 0.001 Mc Nemar's test. The specificity (Spe) and positive predictive value (PPV) of the WB-MRI and BS was 85/82% and 91/86%, respectively. The interobserver agreement between WB-MRI and BS was 71%, Cohen's kappa 0.42. Analysis of the added diagnostic value of gadolinium revealed Se/Spe/PPV/NPV of 98/93/92/98% for the NE WB-MRI and 99/93/85/100% for the WM-MRI + Gd, P > 0.05 binary logistic regression with Fischer's exact test.

CONCLUSION

WB-MRI exceeds the sensitivity of BS without compromising the specificity, even after omitting the gadolinium enhancer.

Magnetic Resonance Imaging for Translational Research in Oncology

The translation of results from the preclinical to the clinical setting is often anything other than straightforward. Indeed, ideas and even very intriguing results obtained at all levels of preclinical research, i.e., in vitro, on animal models, or even in clinical trials, often require much effort to validate, and sometimes, even useful data are lost or are demonstrated to be inapplicable in the clinic. In vivo, small-animal, preclinical imaging uses almost the same technologies in terms of hardware and software settings as for human patients, and hence, might result in a more rapid translation. In this perspective, magnetic resonance imaging might be the most translatable technique, since only in rare cases does it require the use of contrast agents, and when not, sequences developed in the lab can be readily applied to patients, thanks to their non-invasiveness. The wide range of sequences can give much useful information on the anatomy and pathophysiology of oncologic lesions in different body districts. This review aims to underline the versatility of this imaging technique and its various approaches, reporting the latest preclinical studies on thyroid, breast, and prostate cancers, both on small laboratory animals and on human patients, according to our previous and ongoing research lines.

Whole-body MRI to assess bone involvement in prostate cancer and multiple myeloma: comparison of the diagnostic accuracies of the T1, short tau inversion recovery (STIR), and high b-values diffusion-weighted imaging (DWI) sequences

PURPOSE

To compare the diagnostic accuracy of whole-body T1, short tau inversion recovery (STIR), high b-value diffusion-weighted imaging (DWI), and sequence combinations to detect bone involvement in prostate cancer (PCa) and multiple myeloma (MM) patients.

MATERIALS AND METHODS

We included 50 consecutive patients with PCa at high risk for metastasis and 47 consecutive patients with a histologically confirmed diagnosis of MM who received whole-body MRI at two institutions from January to December 2015. Coronal T1, STIR, and reconstructed coronal high b-values DWI were obtained for all patients. Two musculoskeletal radiologists read individual sequences, pairs of sequences (T1-DWI, T1-STIR, and STIR-DWI), and all combined (T1-STIR-DWI) to detect bone involvement. Receiver operating characteristic curve analysis was used to assess diagnostic performance according to a "best valuable comparator" combining baseline and 6-month imaging and clinical and biological data. Interobserver agreement was calculated.

RESULTS

Interobserver agreement for individual and combined MRI sequences was very good in the PCa group and ranged from good to very good in the MM group (0.76-1.00). In PCa patients, T1-DWI, T1-STIR, and T1-STIR-DWI showed the highest performance (sensitivity = 100% [95% CI = 90.5-100%], specificity = 100% [75.3-100%]). In MM patients, the highest performance was achieved by T1-STIR-DWI (sensitivity = 100% [88.4-100%], specificity = 94.1% [71.3-100%]). T1-STIR-DWI significantly outperformed all sequences (p < 0.05) except T1-DWI (p = 0.49).

CONCLUSION

In PCa patients, a combination of either T1-DWI or T1-STIR sequences is not inferior to a combination of three sequences to detect bone metastases. In MM, T1-STIR-DWI and T1-DWI had the highest diagnostic performance for detecting bone involvement.

KEY POINTS

• The sequences used in Whole Body MRI studies to detect bone involvement in prostate cancer and myeloma were evaluated. • In prostate cancer, any pairwise combinations of T1, STIR, and DWI have high diagnostic value. • In myeloma, the combinations T1-STIR-DWI or T1-DWI sequences should be used.

PET/CT features discriminate risk of metastasis among single-bone FDG lesions detected in newly diagnosed non-small-cell lung cancer patients

OBJECTIVES

We investigated the capacity of fluorodeoxyglucose (FDG) PET/CT features for stratifying probability of metastasis for single-bone FDG lesions in non-small-cell lung cancer (NSCLC).

METHODS

Subjects were 118 newly diagnosed NSCLC patients with a solitary bone FDG lesion and no evidence of other distant metastasis based on PET/CT, brain MRI, and contrast-enhanced chest CT. Bone lesion SUV_max and CT findings, primary tumor SUV_max, clinical T stage, and N stage were analyzed.

RESULTS

The bone lesions were determined by biopsy, characteristic MRI findings and clinical follow-up to be metastatic in 33 (28.0%) and benign in 85 cases (72.0%). A cutoff bone SUV_max of 4.3 showed good diagnostic performance (81.8% sensitivity, 84.7% specificity, and 83.9% accuracy), but there was considerable overlap. Bone lesion PET/CT features of SUV_max ≤ 2, osteosclerotic rim or fracture correctly diagnosed 20/20 benign, while SUV_max > 10, soft-tissue mass or bone destruction correctly diagnosed 18/18 metastatic cases. In the remaining 80 cases, bone features of SUV_max > 4.3 and osteolytic change, and lung tumor features of SUV_max > 6.4, ≥ T2 stage (n = 70), and ≥ N1 stage (n = 43) favored metastasis. The presence of one or less of these features correctly diagnosed 38/38 benign, while the presence of four or more features correctly diagnosed 5/5 metastatic cases. The 37 cases with two or three features had either benign (n = 27) or metastatic bone disease (n = 10).

CONCLUSION

Combining bone lesion and lung tumor PET/CT features can help stratify risk of bone metastasis in these patients.

KEY POINTS

• In NSCLC with a single-bone FDG lesion, lesion SUV_maxis useful for differential diagnosis. • CT features of the single-bone FDG lesions provide additional diagnostic value. • High NSCLC SUV_max, greater T stage, and FDG positive nodes also favor metastasis.

Whole Body MRI and oncology: recent major advances

MRI is a very attractive approach for tumour detection and oncological staging with its absence of ionizing radiation, high soft tissue contrast and spatial resolution. Less than 10 years ago the use of Whole Body MRI (WB-MRI) protocols was uncommon due to many limitations, such as the forbidding acquisition times and limited availability. This decade has marked substantial progress in WB-MRI protocols. This very promising technique is rapidly arising from the research world and is becoming a commonly used examination for tumour detection due to recent technological developments and validation of WB-MRI by multiple studies and consensus papers. As a result, WB-MRI is progressively proposed by radiologists as an efficient examination for an expanding range of indications. As the spectrum of its uses becomes wider, radiologists will soon be confronted with the challenges of this technique and be urged to be trained in order to accurately read and report these examinations. The aim of this review is to summarize the validated indications of WB-MRI and present an overview of its most recent advances. This paper will briefly discuss how this examination is performed and which are the recommended sequences along with the future perspectives in the field.

Whole-body MRI for metastatic cancer detection using T2 -weighted imaging with fat and fluid suppression

PURPOSE

To develop a whole-body MRI technique at 3T with improved lesion conspicuity for metastatic cancer detection using fast, high-resolution and high SNR T₂ -weighted (T₂ W) imaging with simultaneous fat and fluid suppression.

THEORY AND METHODS

The proposed dual-echo T₂ -weighted acquisition for enhanced conspicuity of tumors (DETECT) acquires 4 images, in-phase (IP) and out-of-phase (OP) at a short and a long TE using single-shot turbo spin echo. The IP/OP images at the short and long TEs are reconstructed using the standard Dixon and shared-field-map Dixon reconstruction respectively, for robust fat-water separation. An adaptive complex subtraction between the 2 TE water-only images achieves fluid attenuation. DETECT imaging was optimized and evaluated in whole-body imaging of 5 healthy volunteers, and compared against diffusion-weighted imaging with background suppression (DWIBS) in 5 patients with known metastatic renal cell carcinoma.

RESULTS

Robust fat-water separation and fluid attenuation were achieved using the shared-field-map Dixon reconstruction and adaptive complex subtraction, respectively. DETECT imaging technique generated co-registered T₂ W images with and without fat suppression, heavily T₂ W, and fat and fluid suppressed T₂ W whole-body images in <7 min. Compared to DWIBS acquired in 17 min, the DETECT imaging achieved better detection and localization of lesions in patients with metastatic cancer.

CONCLUSION

DETECT imaging technique generates T₂ W images with high resolution, high SNR, minimal geometric distortions, and provides good lesion conspicuity with robust fat and fluid suppression in <7 min for whole-body imaging, demonstrating efficient and reliable metastatic cancer detection at 3T.

Magnetic Resonance Imaging correlates of benign and malignant alterations of the spinal bone marrow

Background and aim of the work: Bone marrow (BM) abnormalities in the spine are a common, sometimes unexpected, finding on Magnetic Resonance Imaging (MRI), which is the most sensitive imaging modality to evaluate the marrow, and their interpretation can be difficult for the unexperienced radiologist. In this review, the MRI appearance of normal age-related BM changes, as well as the imaging features of benign and malignant diseases, are presented. Discussion: A large variety of BM signal alterations has been identified and described, including normal variants, BM reconversion, degenerative changes, infections, spondyloarthritis and osteonecrosis, trauma, neoplastic lesions (both primary or metastatic), post-radiation and chemotherapy sequelae. Conclusions: Knowledge of normal age-related BM appearance, normal variants and patterns of involvement in focal and diffuse bone diseases is essential, together with clinical and laboratory data, to narrow the list of the possible differential diagnoses. The radiologist should be familiar with these signal changes, as they can sometimes be discovered incidentally. In this context, it is equally important not to attribute pathological significance to benign alterations and to promptly detect signs of malignant diseases. (www.actabiomedica.it)

Whole Body MRI and oncology: recent major advances

MRI is a very attractive approach for tumour detection and oncological staging with its absence of ionizing radiation, high soft tissue contrast and spatial resolution. Less than 10 years ago the use of Whole Body MRI (WB-MRI) protocols was uncommon due to many limitations, such as the forbidding acquisition times and limited availability. This decade has marked substantial progress in WB-MRI protocols. This very promising technique is rapidly arising from the research world and is becoming a commonly used examination for tumour detection due to recent technological developments and validation of WB-MRI by multiple studies and consensus papers. As a result, WB-MRI is progressively proposed by radiologists as an efficient examination for an expanding range of indications. As the spectrum of its uses becomes wider, radiologists will soon be confronted with the challenges of this technique and be urged to be trained in order to accurately read and report these examinations. The aim of this review is to summarize the validated indications of WB-MRI and present an overview of its most recent advances. This paper will briefly discuss how this examination is performed and which are the recommended sequences along with the future perspectives in the field.

Whole-body magnetic resonance imaging for detection of skeletal metastases in children and young people with primary solid tumors - systematic review

BACKGROUND

Many solid neoplasms have a propensity for osteomedullary metastases of which detection is important for staging and subsequent treatment. Whole-body magnetic resonance imaging (WB-MRI) has been shown to accurately detect osteomedullary metastases in adults, but these findings cannot be unconditionally extrapolated to staging of children with malignant solid tumors.

OBJECTIVE

To conduct a literature review on the sensitivity of WB-MRI for detecting skeletal metastases in children with solid tumors.

MATERIALS AND METHODS

Searches in MEDLINE and EMBASE databases up to 15 May 2017 were performed to identify studies on the diagnostic value of WB-MRI. Inclusion criteria were children and adolescents (age <21 years) with a primary solid tumor who were evaluated for skeletal metastases by WB-MRI and compared to any type of reference standard. The number of included patients had to be at least five and data on true positives, true negatives, false-positives and false-negatives had to be extractable.

RESULTS

Five studies including 132 patients (96 patients with solid tumors) were eligible. Patient groups and used reference tests were heterogeneous, producing unclear or high risk of bias. Sensitivity of WB-MRI ranged between 82% and 100%. The positive predictive value of WB-MRI was variable among the studies and influenced by the used reference standard.

CONCLUSION

Although WB-MRI may seem a promising radiation-free technique for the detection of skeletal metastases in children with solid tumors, published studies are small and too heterogeneous to provide conclusive evidence that WB-MRI can be an alternative to currently used imaging techniques.

Accuracy of Whole-Body DWI for Metastases Screening in a Diverse Group of Malignancies: Comparison With Conventional Cross-Sectional Imaging and Nuclear Scintigraphy

OBJECTIVE

The purpose of this study is to assess the role of whole-body (WB) DWI as a screening modality for the detection of metastases and to compare it to conventional cross-sectional imaging modalities or nuclear scintigraphy in a population with various histopathologic malignancies.

SUBJECTS AND METHODS

WB DWI and conventional imaging (CT, MRI, or scintigraphy) were performed for patients with known malignancies for metastatic workup, and these patients were followed up for a period of 1 year. Two radiologists assessed WB DW images separately, and conventional images were assessed by the senior radiologist. The metastatic lesions were classified into four regions: liver, lung, skeletal system, and lymph nodes. The reference standard was considered on the basis of histopathologic confirmation or clinical follow-up of the metastatic lesions.

RESULTS

WB DWI was slightly inferior to conventional imaging modalities for the detection of hepatic metastases (sensitivity, 86.6% vs 93.3%; specificity, 91.6% vs 95.8%; and accuracy, 89.7% vs 94.8%) and skeletal metastases (sensitivity, 81.8% vs 89.4%; specificity, 86.4% vs 94.3%; and accuracy, 85.2% vs 93.0%); however, the differences were not statistically significant (p = 0.625 for hepatic metastases and p = 0.0953 for skeletal metastases, McNemar test). WB DWI was statistically significantly inferior to conventional imaging for the detection of lymph node metastases (sensitivity, 74.0% vs 81.5%; specificity, 87.9% vs 90.1%; accuracy, 81.4% vs 86.0%; p = 0.0389). WB DWI was statistically significantly inferior to conventional imaging for the detection of pulmonary metastases (sensitivity, 33.3% vs 100.0%; specificity, 90.9% vs 100.0%; accuracy, 60.8% vs 100.0%; p = 0.045).

CONCLUSION

WB DWI can be used for screening hepatic and skeletal metastases, but its reliability as the sole imaging sequence for the detection of lymph nodal and pulmonary metastases is poor and, at present, it cannot replace conventional imaging modalities.

Optimising TNM Staging of Patients with Prostate Cancer Using WB-MRI

Multiparametric Magnetic Resonance Imaging (mp-MRI) is the current standard of reference for the local staging of prostate cancer (PCa). On the other hand, despite the low sensitivity and specificity of Technetium Bone Scanning (BS) for the detection of bone metastases (BM) and of Body Computed Tomography CT for the detection of lymph node metastases (LNM), these techniques are routinely used, in the current clinical practice. Nevertheless, whole Body MRI (WB-MRI) and Positron Emission Tomography Computed Tomography (PET-CT) are emerging as robust tools for the staging of oncologic patients, including those with (PCa).

The available techniques (BS, WB-MRI, PET, CT) for the detection of BM in oncologic patients were compared and showed striking center differences in terms of anatomic sequences and planes used. This heterogeneity and the long acquisition time of WB-MRI protocols – due to the addition of multiple anatomic sequences in different planes – questioned whether a single three dimensional (3D) sequence could replace the multiple anatomic sequences used for node and bone staging of PCa. We demonstrated that WB-MRI is a credible tool for the detection of bone and node metastasis.

The second question addressed the possibility to obtain a complete TNM staging of PCa in a single MRI session. A WB-MRI protocol was developed to enable complete, T (local), N (regional) and M (distant) staging of PCa in a single session, in less than an hour. This ‘all-in-one’ protocol proved to be as efficient as the sum of exams currently in use for the staging of PCa (ie: mp-MRI of the prostate for ‘T’ staging, Thoraco-abdominal CT for ‘N’ staging and bone scintigraphy for ‘M’ staging).

Oncological whole-body staging in integrated (18)F-FDG PET/MR: Value of different MR sequences for simultaneous PET and MR reading

OBJECTIVE

To evaluate different magnetic resonance (MR) imaging sequences in integrated positron emission tomography (PET)/MR concerning their ability to detect tumors and allocate increased radionuclide uptake on (18)F-fluorodeoxyglucose ((18)F-FDG) PET in intraindividual comparison with computed tomography (CT) from PET/CT.

MATERIAL AND METHODS

Sixty-one patients (34 female, 27 male, mean age 57.6 y) who were examined with contrast-enhanced PET/CT and subsequent PET/MR (mean delay for PET/MR after injection: 147 ± 43 min) were included. A maximum of ten (18)F-FDG-avid lesions per patient were analyzed on CT from PET/CT and with the following MR sequences from PET/MR: T2, turbo inversion recovery magnitude (TIRM), non-enhanced T1, contrast-enhanced T1, and diffusion-weighted imaging (DWI). All lesions were rated using a four-point ordinal scale (scored from 0 to 3) concerning visual detectability of the lesion against the surrounding background and anatomical allocation of the PET finding. In each category (detectability and allocation), Wilcoxon rank sum tests were performed. Bonferroni-Holm correction was performed to prevent α-error accumulation.

RESULTS

In 225 (18)F-FDG-avid lesions (156 confirmed as malignant by radiological follow up, 69 by histopathology), visual detectability was comparably high on CT (mean: 2.5 ± 0.9), TIRM (mean: 2.5 ± 0.9), T2 (mean: 2.4 ± 0.9), and DWI (mean: 2.5 ± 1.0) and was significantly higher than on non-enhanced T1 (mean: 2.2 ± 1.0). While anatomic allocation of the PET finding was comparable with CT (mean: 2.6 ± 0.7), T2 (mean: 2.6 ± 0.7), and TIRM (mean: 2.8 ± 0.7), it was significantly higher compared to DWI (mean: 2.1 ± 1.0) and non-enhanced T1 (mean: 2.4 ± 0.8).

CONCLUSION

In conclusion, T2, TIRM, and contrast-enhanced T1 provide a high quality of lesion detectability and anatomical allocation of FDG-avid foci. Their performance is at least comparable to contrast-enhanced PET/CT. Non-enhanced T1 may be omitted and the necessity of DWI should be further investigated for specific questions, such as assessment of the liver.

Prospective evaluation of planar bone scintigraphy, SPECT, SPECT/CT, 18F-NaF PET/CT and whole body 1.5T MRI, including DWI, for the detection of bone metastases in high risk breast and prostate cancer patients: SKELETA clinical trial

PURPOSE

Detection of bone metastases in breast and prostate cancer patients remains a major clinical challenge. The aim of the current trial was to compare the diagnostic accuracy of (99m)Tc-hydroxymethane diphosphonate ((99m)Tc-HDP) planar bone scintigraphy (BS), (99m)Tc-HDP SPECT, (99m)Tc-HDP SPECT/CT, (18)F-NaF PET/CT and whole body 1.5 Tesla magnetic resonance imaging (MRI), including diffusion weighted imaging, (wbMRI+DWI) for the detection of bone metastases in high risk breast and prostate cancer patients.

MATERIAL AND METHODS

Twenty-six breast and 27 prostate cancer patients at high risk of bone metastases underwent (99m)Tc-HDP BS, (99m)Tc-HDP SPECT, (99m)Tc-HDP SPECT/CT, (18)F-NaF PET/CT and wbMRI+DWI. Five independent reviewers interpreted each individual modality without the knowledge of other imaging findings. The final metastatic status was based on the consensus reading, clinical and imaging follow-up (minimal and maximal follow-up time was 6, and 32 months, respectively). The bone findings were compared on patient-, region-, and lesion-level.

RESULTS

(99m)Tc-HDP BS was false negative in four patients. In the region-based analysis, sensitivity values for (99m)Tc-HDP BS, (99m)Tc-HDP SPECT, (99m)Tc-HDP SPECT/CT, (18)F-NaF PET/CT, and wbMRI+DWI were 62%, 74%, 85%, 93%, and 91%, respectively. The number of equivocal findings for (99m)Tc-HDP BS, (99m)Tc-HDP SPECT, (99m)Tc-HDP SPECT/CT, (18)F-NaF PET/CT and wbMRI+DWI was 50, 44, 5, 6, and 4, respectively.

CONCLUSION

wbMRI+DWI showed similar diagnostic accuracy to (18)F-NaF PET/CT and outperformed (99m)Tc-HDP SPECT/CT, and (99m)Tc-HDP BS.

Comparative accuracy of intravenous contrast-enhanced CT versus noncontrast CT plus intravenous contrast-enhanced CT in the detection and characterization of patients with hypervascular liver metastases: a critically appraised topic

RATIONAL AND OBJECTIVES

To evaluate whether addition of nonenhanced computed tomography (NECT) to intravenous contrast-enhanced (CE) abdominal CT improves detection or characterization of hypervascular liver masses. Patients were referred for initial staging or follow-up with known breast, melanoma, neuroendocrine, or thyroid cancer.

MATERIAL AND METHODS

The literature was searched using the patient, intervention, comparison, and outcome (PICO) method. Retrieved articles were critically appraised and assigned a level of evidence based on the Oxford University Centre for Evidence-based Medicine hierarchy of validity for diagnostic studies.

RESULTS

One thousand one hundred studies were reviewed; only 11 studies matched the PICO of our study and were appraised. Most of the appraised articles were published in the 1990s using older technology and contrast delivery. The retrieved diagnostic performance for characterization of liver metastases showed sensitivity/specificity of 97%/76% for NECT, 97%/75% for arterial CT, and 98%/76% for portal venous phase CT in patients with breast cancer; sensitivity of 96% (arterial and portal CT) versus 100% (NECT, arterial and portal CT) in patients with melanoma; and sensitivity of 43% (portal CT) versus 17% (NECT) in patients with neuroendocrine tumor. No primary study was found for performance of different CT protocols in patients with thyroid cancer. Available evidence showed radiologists reported more conspicuous liver masses on CECT compared to NECT in patients with breast or neuroendocrine cancer.

CONCLUSIONS

Based on existing evidence, NECT only adds a small incremental value to CECT for detection/characterization of hypervascular liver metastases. Addition of NECT increases patient's exposure to radiation and the number of images available for interpretation.

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.

Ewing sarcoma dissemination and response to T-cell therapy in mice assessed by whole-body magnetic resonance imaging

BACKGROUND

Novel treatment strategies in Ewing sarcoma include targeted cellular therapies. Preclinical in vivo models are needed that reflect their activity against systemic (micro)metastatic disease.

METHODS

Whole-body magnetic resonance imaging (WB-MRI) was used to monitor the engraftment and dissemination of human Ewing sarcoma xenografts in mice. In this model, we evaluated the therapeutic efficacy of T cells redirected against the Ewing sarcoma-associated antigen GD2 by chimeric receptor engineering.

RESULTS

Of 18 mice receiving intravenous injections of VH-64 Ewing sarcoma cells, all developed disseminated tumour growth detectable by WB-MRI. All mice had lung tumours, and the majority had additional manifestations in the bone, soft tissues, and/or kidney. Sequential scans revealed in vivo growth of tumours. Diffusion-weighted whole-body imaging with background signal suppression effectively visualised Ewing sarcoma growth in extrapulmonary sites. Animals receiving GD2-targeted T-cell therapy had lower numbers of pulmonary tumours than controls, and the median volume of soft tissue tumours at first detection was lower, with a tumour growth delay over time.

CONCLUSION

Magnetic resonance imaging reliably visualises disseminated Ewing sarcoma growth in mice. GD2-retargeted T cells can noticeably delay tumour growth and reduce pulmonary Ewing sarcoma manifestations in this aggressive disease model.

Conspicuity of bone metastases on fast Dixon-based multisequence whole-body MRI: clinical utility per sequence

PURPOSE

The purpose of the study was to evaluate the conspicuity of bone metastases on each of the numerous sequences produced by fast Dixon-based multisequence whole-body (WB) magnetic resonance imaging (MRI) scanning in order to determine the most clinically useful sequences overall and per anatomic region.

MATERIALS AND METHODS

Twenty-seven breast cancer patients with bone metastases were prospectively studied with fast Dixon-based WB MRI including head/neck, chest, abdominal, pelvic, thigh, calf/feet and either cervical, thoracic and lumbar or cervical/thoracic and thoracic/lumbar regions. Sequences included coronal T2, axial T1 without and with intravenous gadolinium (+C), sagittal T1 spine+C, each associated fat-only (FO) and fat-saturated (FS) sequence, axial diffusion-weighted imaging (DWI) and short tau inversion recovery (STIR). Blinded reviewers evaluated lesion conspicuity, a surrogate of clinical utility, on a five-point scale per anatomic region. Sequences were compared using analysis of variance, differences were detected with Tukey's honestly significant difference test, and the four sequences with highest mean conspicuity were compared to the remainder overall and per anatomic region.

RESULTS

Overall, a significant lesion conspicuity difference was found (P<.0001), and lesion conspicuity was significantly higher on FS T1+C, FO T1+C, T1+C sagittal and FS T1+C axial sequences (P<.0001). Per-region results were the same in the head/neck. Other sequences overlapped with these and included the following: chest/abdomen - FO T2, DWI; pelvis - DWI, FO T2; thigh - FS T2, FO T2, FO T1+C; calf/feet - FS T2, DWI, FO T2, STIR.

CONCLUSION

Overall, bone lesions were most conspicuous on FS T1+C sagittal, FO T1+C sagittal, T1+C sagittal and FS T1+C axial fast Dixon WB MRI sequences.

Whole-body MR imaging for staging of malignant tumors in pediatric patients: results of the American College of Radiology Imaging Network 6660 Trial

PURPOSE

To compare whole-body magnetic resonance (MR) imaging with conventional imaging for detection of distant metastases in pediatric patients with common malignant tumors.

MATERIALS AND METHODS

This institutional review board-approved, HIPAA-compliant, multicenter prospective cohort study included 188 patients (109 male, 79 female; mean age, 10.2 years; range, < 1 to 21 years) with newly diagnosed lymphoma, neuroblastoma, or soft-tissue sarcoma. Informed consent was obtained and all patients underwent noncontrast material-enhanced whole-body MR imaging and standard-practice conventional imaging. All images were reviewed centrally by 10 pairs of readers. An independent panel verified the presence or absence of distant metastases. Detection of metastasis with whole-body MR and conventional imaging was quantified by using the area under the receiver operating characteristic curve (AUC). The effects of tumor subtype, patient age, and distant skeletal and pulmonary disease on diagnostic accuracy were also analyzed.

RESULTS

Of the 134 eligible patients, 66 (33 positive and 33 negative for metastasis) were selected for image review and analysis. Whole-body MR imaging did not meet the noninferiority criterion for accuracy when compared with conventional imaging for detection of metastasis (difference between average AUCs was -0.03 [95% confidence interval: -0.10, 0.04]); however, the average AUC for solid tumors was significantly higher than that for lymphomas (P = .006). More skeletal metastases were detected by using whole-body MR imaging than by using conventional imaging (P = .03), but fewer lung metastases were detected (P < .001). Patient age did not affect accuracy.

CONCLUSION

The noninferior accuracy for diagnosis of distant metastasis in patients with common pediatric tumors was not established for the use of whole-body MR imaging compared with conventional methods. However, improved accuracy was seen with whole-body MR imaging in patients with nonlymphomatous tumors.

Whole-body MRI: comprehensive evaluation on a 48-channel 3T MRI system in less than 40 minutes. Preliminary results

OBJECTIVE: To evaluate a comprehensive MRI protocol that investigates for cancer, vascular disease, and degenerative/inflammatory disease from the head to the pelvis in less than 40 minutes on a new generation 48-channel 3T system. MATERIALS AND METHODS: All MR studies were performed on a 48-channel 3T MR scanner. A 20-channel head/neck coil, two 18-channel body arrays, and a 32-channel spine array were employed. A total of 4 healthy individuals were studied. The designed protocol included a combination of single-shot T2-weighted sequences, T1-weighted 3D gradient-echo pre- and post-gadolinium. All images were retrospectively evaluated by two radiologists independently for overall image quality. RESULTS: The image quality for cancer was rated as excellent in the liver, pancreas, kidneys, lungs, pelvic organs, and brain, and rated as fair in the colon and breast. For vascular diseases ratings were excellent in the aorta, major branch vessel origins, inferior vena cava, portal and hepatic veins, rated as good in pulmonary arteries, and as poor in the coronary arteries. For degenerative/inflammatory diseases ratings were excellent in the brain, liver and pancreas. The inter-observer agreement was excellent. CONCLUSION: A comprehensive and time efficient screening for important categories of disease processes may be achieved with high quality imaging in a new generation 48-channel 3T system.

The clinical value of routine whole-body magnetic resonance imaging (MRI) in palliative care

BACKGROUND

Whole-body MRI (WBMRI) has become an accessible method for detecting different types of pathologies both in the skeleton and the viscera, which may explain painful conditions, for example tumors and inflammation.

PURPOSE

To assess a possible value of using WBMRI in order to improve palliative care.

MATERIAL AND METHODS

Twenty patients (all eligible patients) admitted to the Department for Palliative Care were consecutively included in this study. They underwent a modified WBMRI, with fewer and shorter pulse sequences than in a standard WBMRI, to reduce patient stress. However, the patients' physicians were to exclude patients where little might be obtained and discomfort, distress, and pain could be induced. The treating physicians registered clinical utility directly after receiving the MRI report in a questionnaire. The registration was repeated after ended treatment.

RESULTS

Eighty percent had new findings detected, and 40% of the patients had a change in treatment due to the MRI result, mainly changes in analgesics and/or radiation therapy.

CONCLUSION

The WBMRI helped the clinicians to improve treatment and a majority of the patients benefited from this. In eight patients the treatment was changed due to the results. The clinical value (utility) was indicated to be high.

Computed tomography and magnetic resonance imaging of the thoracic lymphatic system

Several radiographic diagnostic techniques are currently available to assess the potential involvement of mediastinal lymph nodes in thoracic oncology. In particular, computed tomography and magnetic resonance imaging have been repeatedly validated; these techniques allow adequate imaging with a reasonable accuracy. The morphologic information provided by these techniques is crucial to stage lung cancer and plan treatment. These techniques are also extremely useful to evaluate other disorders and differentiate malignancy from benign disease.

Modern Detection of Prostate Cancer's Bone Metastasis: Is the Bone Scan Era Over?

Prostate cancer cells have an exquisite tropism for bone, which clinically translates into the highest rate of bone metastases amongst male cancers. Although in the latest years there has been an active development of new "bone targeted" therapies, modern diagnostic techniques for bone metastases still relies mostly on (99m)Tc bone scanning (BS) and plain X-ray. BS dramatically lacks specificity and sensitivity. Recent publications using modern imaging technologies have clearly pinpointed that BS grossly underestimates the true prevalence of bone metastasis. In addition BS does not allow tumour measurement and is, therefore, not appropriate to monitor response to therapy. This might be extremely important in patients harbouring high-risk localized disease that are eventually candidate for local therapy. Here we reviewed what are the emerging imaging strategies that are likely to supplant BS and to what extent they can be used in the clinic already.

Diagnostic value of whole-body magnetic resonance imaging for bone metastases: a systematic review and meta-analysis

PURPOSE

To assess the overall diagnostic accuracy of whole-body magnetic resonance imaging (WB-MRI) in detecting bone metastases with a meta-analysis.

MATERIALS AND METHODS

The MEDLINE, EMBASE, Cancerlit, and Cochrane Library databases were searched from January 1995 to September 2010 for studies evaluating the accuracy of WB-MRI in detecting bone metastases. Histopathologic analysis and/or close clinical and imaging follow-up for at least 6 months was assessed. Meta-analysis methods were used to pool sensitivity and specificity and to construct summary receiver-operating characteristics.

RESULTS

A total of 11 studies with 495 patients who fulfilled all of the inclusion criteria were considered for the analysis. No publication bias was found. WB-MRI had a pooled sensitivity of 0.899 (95% confidence interval [CI], 0.845-0.939) and a pooled specificity of 0.918 (95% CI, 0.882-0.946). The subgroup without diffusion-weighted imaging (DWI) positive results had higher pooled specificity 0.961 (95% CI, 0.922-0.984) than the subgroup with DWI (P < 0.05).

CONCLUSION

WB-MRI was an accurate, cost-effective tool in detecting bone metastases. WB-MRI without DWI may improve the specificity of detecting bone metastases. DWI seems to be a sensitive but rather unspecific modality for the detection of bone metastatic disease. High-quality prospective studies regarding WB-MRI in detecting bone metastases still need to be conducted.

Recent technological and application developments in computed tomography and magnetic resonance imaging for improved pulmonary nodule detection and lung cancer staging

This review compares the emerging technologies and approaches in the application of magnetic resonance (MR) and computed tomography (CT) imaging for the assessment of pulmonary nodules and staging of malignant findings. Included in this review is a brief definition of pulmonary nodules and an introduction to the challenges faced. We have highlighted the current status of both MR and CT for the early detection of lung nodules. Developments are detailed in this review for the management of pulmonary nodules using advanced imaging, including: dynamic imaging studies, dual energy CT, computer aided detection and diagnosis, and imaging assisted nodule biopsy approaches which have improved lung nodule detection and diagnosis rates. Recent advancements linking in vivo imaging to corresponding histological pathology are also highlighted. In vivo imaging plays a pivotal role in the clinical staging of pulmonary nodules through TNM assessment. While CT and positron emission tomography (PET)/CT are currently the most commonly clinically employed modalities for pulmonary nodule staging, studies are presented that highlight the augmentative potential of MR.

Effectiveness of the STIR turbo spin-echo sequence MR imaging in evaluation of lymphadenopathy in esophageal cancer

PURPOSE

We have investigated the utility of the STIR TSE sequence in the differentiation of benign from malignant mediastinal lymph nodes in patients with esophageal cancer.

PATIENTS AND METHODS

This study included 35 consecutive patients who were diagnosed as esophageal cancer and were undergone surgery. STIR TSE sequences were obtained as the ECG trigger. The signal intensity of the benign and malign lymph nodes, normal esophagus, and pathologic esophagus can be calculated on STIR sequence.

RESULTS

Pathologically, the number of total lymph nodes in 35 operated cases was 482. Approximately 152 lymph nodes were detected with MR imaging. Of these, 28 were thought to be malignant, and 124 were thought to be benign, although 32 were malignant and 120 were benign according pathological results. The ratio of benign lymph node intensity value to normal esophagus intensity value was 0.73±0.3. The ratio of malignant lymph node intensity value to normal esophagus intensity value ratio was 2.03±0.4. According to these results, the sensitivity of MR was 81.3%, the specificity was 98.3%.

CONCLUSION

We think that if motionless images can be obtained with MRI, we may be able to differentiate benign lymph nodes from malignant ones.

Whole-body diffusion-weighted imaging vs. FDG-PET for the detection of non-small-cell lung cancer. How do they measure up?

OBJECTIVE

To compare the diagnostic efficacy of whole-body diffusion-weighted imaging (WB-DWI) and [18F] fluoro-2-D-glucose PET/CT(FDG-PET/CT)for assessment of non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

A group of 56 patients (21 female, 35 male; 35-76 years) with NSCLC proved by pathologic examination or follow-up imaging findings was set as reference standards, and all patients underwent both WB-DWI at 1.5T (MAGNETOM Avanto) and PET/CT (Biograph 16). For WB-DWI, a free breathing diffusion-weighted single-shot spin-echo epi-sequence in five-stations (head-neck, thorax, abdomen, pelvis-thigh) was used. Each station-series contained 30 contiguous axial slices. Imaging parameters: FOV 360x360 mm, matrix size 128x80. B-values: 0 and 1000 s/mm(2) applied along x, y and z, 5 averages, acquisition time: 2.23 min/series, total: 11.55 min. The efficacy of WB-DWI and PET/CT were determined in a blinded reading by two radiologists and two nuclear medicine physicians using pathology and size change during follow up exams as the reference standard.

RESULTS

Primary tumors (n=56 patients) were correctly detected in 56 (100%) patients by both PET/CT and WB-DWI. Ninety-six lymph nodes metastases were determined with pathologic and follow-up examinations. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) being for lymph node metastases: 91%, 90%, 90%, 96%, 80% with WB-DWI and 98%, 97%, 97%, 99%, 93% with PET-CT, other metastases: 90%, 95%, 92%, 97%, 83% with WB-DWI and 98%, 100%, 98%, 100%, 95% with PET-CT). Differences in the accuracy of lymph node metastasis detection between PET/CT and WB-DWI (P=.031) were significant. The differences were not statistically significant for detection of other metastases.

CONCLUSIONS

WB-DWI is a feasible clinical technique for the assessment of NSCLC, lymph nodes and metastastic spread with high sensitivity and accuracy, but it was limited in the evaluation of neck lymph node metastases and small metastastic lung nodules.

Metastases in mediastinal and hilar lymph nodes in patients with non-small cell lung cancer: quantitative assessment with diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient

OBJECTIVE

To evaluate diffusion-weighted magnetic resonance (DW-MR) imaging for detection of metastases in lymph nodes by using quantitative analysis.

METHODS

Seventy patients with non-small cell lung cancer were examined with DW and short inversion time inversion recovery (STIR) turbo-spin-echo MR imaging. Apparent diffusion coefficient of each lung cancer and lymph node was calculated from DW-MR images. Difference of the apparent diffusion coefficient in a lung cancer and a lymph node was calculated (D1). From STIR turbo-spin-echo MR images, ratios of signal intensity in a lymph node to that in a 0.9% saline phantom was calculated (lymph node-saline ratio [LSR1]). For quantitative analysis, the threshold value for a positive test was determined on a per node basis and tested for ability to enable a correct diagnosis on a per patient basis. Results of quantitative analyses of DW- and STIR-MR images were compared on a per patient basis with McNemar testing.

RESULTS

Mean D1 in the lymph node group with metastases was lower than that in the group without metastases (P < 0.001). When an D1 of 0.24 x 10(-3) mm2/s was used as the positive test threshold, sensitivity, specificity, and accuracy were 69.2%, 100%, and 94.0%, respectively, on a per patient basis. There was no significant difference (P > 0.05) between quantitative analyses of DW-MR images and STIR-MR images.

CONCLUSIONS

Quantitative analysis of DW-MR images enables differentiation of lymph nodes with metastasis from those without.

Detection of bone metastases using diffusion weighted magnetic resonance imaging: comparison with (11)C-methionine PET and bone scintigraphy

PURPOSE

We evaluated the ability of diffusion-weighted imaging (DWI) to detect bone metastasis by comparing the results obtained using this modality with those obtained using (11)C-methionine (MET) positron emission tomography (PET) and bone scintigraphy.

MATERIALS AND METHODS

This retrospective study involved 29 patients with bone metastasis. DWI was obtained using a single-shot echo planar imaging (EPI) sequence with fat suppression using a short inversion time inversion recovery sequence. The detection capabilities of DWI for bone metastases were compared with those of whole body MET PET (in 19 patients) and 99mTc-methylene diphosphonate bone scintigraphy (in 15 patients).

RESULTS

Among the 19 patients who were diagnosed using DWI and PET, the PET identified 39 bone metastases, while the DWI identified 60 metastases out of 69 metastases revealed with conventional magnetic resonance imaging (MRI). Among the 15 patients who were diagnosed using DWI and bone scintigraphy, the bone scintigraphy identified 18 bone metastases, while the DWI identified 72 metastases out of 78 metastases revealed with conventional MRI. The overall bone metastasis detection rates were 56.5% for PET, 23.1% for bone scintigraphy and 92.3% for DWI.

CONCLUSION

DWI is a very sensitive method for detecting bone metastasis and is superior to MET PET and bone scintigraphy in terms of its detection capabilities.

Whole-body diffusion-weighted imaging for staging malignant lymphoma in children

CT is currently the mainstay in staging malignant lymphoma in children, but the risk of second neoplasms due to ionizing radiation associated with CT is not negligible. Whole-body MRI techniques and whole-body diffusion-weighted imaging (DWI) in particular, may be a good radiation-free alternative to CT. DWI is characterized by high sensitivity for the detection of lesions and allows quantitative assessment of diffusion that may aid in the evaluation of malignant lymphomas. This article will review whole-body MRI techniques for staging malignant lymphoma with emphasis on whole-body DWI. Furthermore, future considerations and challenges in whole-body DWI will be discussed.

Detection of bone metastases in non-small cell lung cancer patients: comparison of whole-body diffusion-weighted imaging (DWI), whole-body MR imaging without and with DWI, whole-body FDG-PET/CT, and bone scintigraphy

PURPOSE

To prospectively compare the capability for bone metastasis assessment of whole-body diffusion-weighted imaging (DWI), magnetic resonance imaging (MRI) without and with DWI, [(18)F] fluoro-2-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) and bone scintigraphy in non-small cell carcinoma (NSCLC) patients.

MATERIALS AND METHODS

In all, 115 consecutive NSCLC patients (66 men, 49 women; mean age 72 years) prospectively underwent whole-body MRI, PET/CT, and bone scintigraphy before treatment. For each method, probability of metastasis was independently assessed by using a 5-point visual scoring system on a per-site basis. Receiver operating characteristic (ROC)-based positive tests were used to determine the practical threshold value for each method on a per-site basis. Sensitivities, specificities, and accuracies were then compared on a per-site and per-patient basis by means of McNemar's test.

RESULTS

When the practical threshold values were adapted, specificity and accuracy of whole-body MRI with DWI were significantly higher than those of bone scintigraphy and PET/CT (P < 0.05). On a per-patient basis, specificity and accuracy of whole-body MRI with DWI were significantly higher than those of bone scintigraphy (P < 0.05).

CONCLUSION

Whole-body MRI with DWI can be used for bone metastasis assessment of NSCLC patients as accurate as bone scintigraphy and/or PET/CT.

Comparison of STIR turbo SE imaging and diffusion-weighted imaging of the lung: capability for detection and subtype classification of pulmonary adenocarcinomas

OBJECTIVE

The aim of the study was to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) for detection and subtype classification in pulmonary adenocarcinomas through comparison with short TI inversion recovery turbo spin-echo imaging sequence (STIR).

METHODS

Thirty-two patients (mean age, 65.2 years) with 33 adenocarcinomas (mean diameter, 27.6 mm) were enrolled in this study. The detection rates of both sequences were compared. The ADC values on DWI and the contrast ratio (CR) between cancer and muscle on STIR were measured and those were compared across subtype classifications. Finally, ROC-based positive tests were performed to differentiate subtype classifications, and differentiation capabilities were compared.

RESULTS

The DWI detection rate [85% (28/33)] was significantly lower than that of STIR [100% (33/33), P < 0.05]. The ADC values showed no significant difference regarding subtype classification; however, the CRs of bronchio-alveolar carcinomas (BACs) were significantly lower than those of other types (P < 0.05). When threshold values for differentiating BACs from others were adapted, the sensitivity and accuracy of DWI were significantly lower than those of STIR (P < 0.05). For differentiating adenocarcinomas with mixed subtypes from those with no BA component, there were no significant differences between the two sequences.

CONCLUSION

STIR is more sensitive for detection and subtype classification than DWI.

Comparative study of two whole-body imaging techniques in the case of melanoma metastases: advantages of multi-contrast MRI examination including a diffusion-weighted sequence in comparison with PET-CT

The aim of our study was to compare whole-body MRI (Magnetic Resonance Imaging) with a multi-contrast protocol including a DW (Diffusion Weighted) sequence to PET-CT (Positron Emission Tomography) using (18)FDG (18F-fluoroDeoxyGlucose) for staging advanced melanoma. In a first part, we compared the respective overall accuracy of each modality. We analyzed in a second part the benefits of a DW sequence added to the standard whole-body MRI protocol. Among the population of the 35 patients who experienced the two examinations of our prospective blinded study, we were able to detect 120 lesions and 70 of them were found malignant. The sensitivity and specificity for whole-body MRI were respectively 82% and 97%, while PET-CT reached 72.8% and 92.7%. DW sequence allowed the detection of 14 supplementary malignant lesions (20%) in comparison with standard MRI protocol. Moreover, this technique has been shown to be the most accurate for detecting metastases in the liver, bone, subcutaneous and intra-peritoneal sites. Consequently, a DW sequence should be added systematically to the standard whole-body MRI oncologic protocol because of its high added-value for metastasis detection.