Introduction
Hybrid imaging systems providing morphological and functional data in a single session have been available for oncological imaging for some time. So far, computed tomography (CT) has ...been the morphological method-of-choice for inclusion into these hybrid imaging systems. However, recently, research has focused on hardware-based fusion of function with magnetic resonance imaging (MRI) rather than CT.
Objectives
Now that the first head-only positron emission tomography (PET)/MRI systems have been installed and whole-body systems are to be expected in the near future, potential indications in clinical oncology have to be addressed.
Discussion
This article discusses potential indications of PET/MRI in whole-body oncology imaging. Potential advantages and disadvantages compared with currently available hybrid imaging systems will be reviewed.
Purpose To determine whether signal intensity (SI) in T1 sequences as a potential indicator of gadolinium deposition increases after repeated administration of the macrocyclic gadolinium-based ...contrast agents (GBCAs) gadoteridol and gadoterate meglumine in a pediatric cohort. Materials and Methods This retrospective case-control study of children with brain tumors who underwent nine or more contrast material-enhanced brain magnetic resonance (MR) imaging studies from 2008 to 2015 was approved by the local ethics board. Informed consent was obtained for MR imaging. Twenty-four case patients aged 5-18 years and appropriate control patients with nonpathologic MR neuroimaging findings (and no GBCA administration), matched for age and sex, were inculded. SI was measured on unenhanced T1-weighted MR images for the following five regions of interest (ROIs): the dentate nucleus (DN), pons, substantia nigra (SN), pulvinar thalami, and globus pallidus (GP). Paired t tests were used to compare SI and SI ratios (DN to pons, GP to thalamus) between case patients and control patients. Pearson correlations between relative signal changes and the number of GBCA administrations and total GBCA dose were calculated. Results The mean number of GBCA administrations was 14.2. No significant differences in mean SI for any ROI and no group differences were found when DN-to-pons and GP-to-pulvinar ratios were compared (DN-to-pons ratio in case patients: mean, 1.0083 ± 0.0373 standard deviation; DN-to-pons ratio in control patients: mean, 1.0183 ± 0.01917; P = .37; GP-to-pulvinar ratio in case patients: mean, 1.1335 ± 0.04528; and GP-to-pulvinar ratio in control patients: mean, 1.1141 ± 0.07058; P = .29). No correlation was found between the number of GBCA administrations or the total amount of GBCA administered and signal change for any ROI. (Number of GBCA applications: DN: r = -0.254, P = .31; pons: r = -0.097, P = .65; SN: r = -0.194, P = .38; GP: r = -0.175, P = .41; pulvinar: r = -0.067, P = .75; total amount of administered GBCA: DN: r = 0.091, P = .72; pons: r = 0.106, P = .62; SN: r = -0.165, P = .45; GP: r = 0.111, P = .61; pulvinar: r = 0.173, P = .42.) Conclusion Multiple intravenous administrations of these macrocyclic GBCAs in children were not associated with a measurable increase in SI in T1 sequences as an indicator of brain gadolinium deposition detectable by using MR imaging. Additional imaging and pathologic studies are needed to confirm these findings.
RSNA, 2017 Online supplemental material is available for this article.
Our purpose was to investigate differences between PET/MRI and PET/CT in lesion detection and classification in oncologic whole-body examinations and to investigate radiation exposure differences ...between the 2 modalities.
In this observational single-center study, 1,003 oncologic examinations (918 patients; mean age, 57.8 ± 14.4 y) were included. Patients underwent PET/CT and subsequent PET/MRI (149.8 ± 49.7 min after tracer administration). Examinations were reviewed by radiologists and nuclear medicine physicians in consensus. Additional findings, characterization of indeterminate findings on PET/CT, and missed findings on PET/MRI, including their clinical relevance and effective dose of both modalities, were investigated. The McNemar test was used to compare lesion detection between the 2 hybrid imaging modalities (
< 0.001, indicating statistical significance).
Additional information on PET/MRI was reported for 26.3% (264/1,003) of examinations, compared with PET/CT (
< 0.001). Of these, additional malignant findings were detected in 5.3% (53/1,003), leading to a change in TNM staging in 2.9% (29/1,003) due to PET/MRI. Definite lesion classification of indeterminate PET/CT findings was possible in 11.1% (111/1,003) with PET/MRI. In 2.9% (29/1,003), lesions detected on PET/CT were not visible on PET/MRI. Malignant lesions were missed in 1.2% (12/1,003) on PET/MRI, leading to a change in TNM staging in 0.5% (5/1,003). The estimated mean effective dose for whole-body PET/CT amounted to 17.6 ± 8.7 mSv, in comparison to 3.6 ± 1.4 mSv for PET/MRI, resulting in a potential dose reduction of 79.6% (
< 0.001).
PET/MRI facilitates staging comparable to that of PET/CT and improves lesion detectability in selected cancers, potentially helping to promote fast, efficient local and whole-body staging in 1 step, when additional MRI is recommended. Furthermore, younger patients may benefit from the reduced radiation exposure of PET/MRI.
In oncology, staging forms the basis for prognostic consideration and directly influences patient care by determining the therapeutic approach. Cross-sectional imaging techniques, especially when ...combined with PET information, play an important role in cancer staging. With the recent introduction of integrated whole-body PET/MRI into clinical practice, a novel metabolic-anatomic imaging technique is now available. PET/MRI seems to be highly accurate in T-staging of tumor entities for which MRI has traditionally been favored, such as squamous cell carcinomas of the head and neck. By adding functional MRI to PET, PET/MRI may further improve diagnostic accuracy in the differentiation of scar tissue from recurrence of tumors such as rectal cancer. This hypothesis will have to be assessed in future studies. With regard to N-staging, PET/MRI does not seem to provide a considerable benefit as compared with PET/CT but provides similar N-staging accuracy when applied as a whole-body staging approach. M-staging will benefit from MRI accuracy in the brain and the liver. The purpose of this review is to summarize the available first experiences with PET/MRI and to outline the potential value of PET/MRI in oncologic applications for which data on PET/MRI are still lacking.
With integrated whole-body PET/MRI, a novel metabolic-anatomic imaging technique recently has been introduced into clinical practice. This review addresses PET/MRI of bone tumors, soft-tissue ...sarcoma, melanoma, and lymphoma. If PET/MRI literature is not yet available for some types of tumors, potential indications are based on available PET/CT and MRI data. PET/MRI seems to be of benefit in T-staging of primary bone tumors and soft-tissue sarcomas. With regard to N-staging, PET/MRI can be considered similarly accurate to PET/CT when applied as a whole-body staging approach. M-staging will benefit from MRI accuracy in the brain, the liver, and bone.
Objectives
To compare the diagnostic performance of
18
FFDG PET/MRI, MRI, CT, and bone scintigraphy for the detection of bone metastases in the initial staging of primary breast cancer patients.
...Material and methods
A cohort of 154 therapy-naive patients with newly diagnosed, histopathologically proven breast cancer was enrolled in this study prospectively. All patients underwent a whole-body
18
FFDG PET/MRI, computed tomography (CT) scan, and a bone scintigraphy prior to therapy. All datasets were evaluated regarding the presence of bone metastases. McNemar
χ
2
test was performed to compare sensitivity and specificity between the modalities.
Results
Forty-one bone metastases were present in 7/154 patients (4.5%). Both
18
FFDG PET/MRI and MRI alone were able to detect all of the patients with histopathologically proven bone metastases (sensitivity 100%; specificity 100%) and did not miss any of the 41 malignant lesions (sensitivity 100%). CT detected 5/7 patients (sensitivity 71.4%; specificity 98.6%) and 23/41 lesions (sensitivity 56.1%). Bone scintigraphy detected only 2/7 patients (sensitivity 28.6%) and 15/41 lesions (sensitivity 36.6%). Furthermore, CT and scintigraphy led to false-positive findings of bone metastases in 2 patients and in 1 patient, respectively. The sensitivity of PET/MRI and MRI alone was significantly better compared with CT (
p
< 0.01, difference 43.9%) and bone scintigraphy (
p
< 0.01, difference 63.4%).
Conclusion
18
FFDG PET/MRI and MRI are significantly better than CT or bone scintigraphy for the detection of bone metastases in patients with newly diagnosed breast cancer. Both CT and bone scintigraphy show a substantially limited sensitivity in detection of bone metastases.
Key Points
•
18
FFDG PET/MRI and MRI alone are significantly superior to CT and bone scintigraphy for the detection of bone metastases in patients with newly diagnosed breast cancer.
•
Radiation-free whole-body MRI might serve as modality of choice in detection of bone metastases in breast cancer patients.
For multiparametric magnetic resonance imaging/ultrasound fusion prostate biopsy the number of biopsy cores obtained is arbitrarily established by urologists. Moreover, a general consensus is lacking ...on the number of biopsy cores to be obtained from a single magnetic resonance imaging lesion. Therefore, we evaluated the feasibility of obtaining only 1 biopsy core per magnetic resonance imaging lesion.
We retrospectively evaluated a total of 2,128 biopsy cores of 1,064 prostatic lesions (2 cores per lesion) in 418 patients in regard to prostate cancer detection (histology) and the Gleason score of the first biopsy core compared to the second biopsy core. Two analyses were performed, including patient level analysis based on prostate cancer detection per patient and lesion level analysis based exclusively on the histology of each lesion regardless of the overall histological outcome of the case.
The overall prostate cancer detection rate was 45.7% (191 of 418 patients). The first biopsy core detected 170 of all 191 prostate cancers (89%). In 17 of these 170 prostate cancers (10%) the second biopsy core revealed Gleason score upgrading. Nine of the 21 prostate cancers (43%) missed by the first biopsy core had a Gleason score of 6. Altogether 537 of the 2,128 biopsy cores were positive, including 283 first (26.6%) and 254 second (24%) biopsy cores (p ≤0.001). The concordance between the first and second biopsy cores was 89% (κ = 0.71). There was a discrepancy with Gleason score upgrading in 28 of 212 lesions (13.2%) with positive first and second biopsy cores.
Our study shows that obtaining more than 1 biopsy core per magnetic resonance imaging lesion only slightly improves the prostate cancer detection rate and Gleason grading.
Purpose This study aimed to evaluate the prognostic potential of pre-therapeutic 18 FFDG-PET/CT variables regarding prediction of progression-free survival (PFS) and overall survival (OS) in ...NSCLC-patients. Method NSCLC-patients who underwent pre-therapeutic 18 FFDG-PET/CT were retrospectively analyzed. The following imaging features were collected from the primary tumor: tumor size, tumor density, central necrosis, spicules and SUV max . For standardization, an indexSUV max was calculated (SUV max primary tumor/SUV max liver). Descriptive statistics and correlations of survival time analyses for PFS and OS were calculated using the Kaplan-Meier method and Cox regression including a hazard ratio (HR). A value of p < 0.05 was set as statistically significant. The 95%-confidence intervals (CI) were calculated. The median follow-up time was 63 (IQR 27–106) months. Results This study included a total of 82 patients (25 women, 57 men; mean age: 66 ± 9 years). IndexSUV max (PFS: HR = 1.0, CI: 1.0–1.1, p = 0.49; OS: HR = 1.0, CI: 0.9–1.2, p = 0.41), tumor size (PFS: HR = 1.0, CI: 0.9–1.0, p = 0.08; OS: HR = 1.0, CI: 0.9–1.0, p = 0.07), tumor density (PFS: HR = 0.9, CI: 0.6–1.4, p = 0.73; OS: HR = 0.3; CI: 0.1–1.1; p = 0.07), central necrosis (PFS: HR = 1.0, CI: 0.6–1.8, p = 0.98; OS: HR = 0.6, CI: 0.2–1.9, p = 0.40) and spicules (PFS: HR = 1.0, CI: 0.6–1.9, p = 0.91; OS: HR = 1.3, CI: 0.4–3.7, p = 0.65) did not significantly affect PFS and OS in the study population. An optimal threshold value for the indexSUV max was determined by ROC analysis and Youden’s index. There was no significant difference in PFS with an indexSUV max -threshold of 3.8 (13 vs. 27 months; p = 0.45) and in OS with an indexSUV max -threshold of 4.0 (113 vs. 106 months; p = 0.40). Conclusions SUV max and morphologic parameters from pre-therapeutic 18 FFDG-PET/CT were not able to predict PFS and OS in NSCLC-patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dynamic contrast enhanced imaging (DCE) as an integral part of multiparametric prostate magnet resonance imaging (mpMRI) can be evaluated using qualitative, semi-quantitative, or quantitative ...assessment methods. Aim of this study is to analyze the clinical benefits of these evaluations of DCE regarding clinically significant prostate cancer (csPCa) detection and grading. 209 DCE data sets of 103 consecutive patients with mpMRI (T2, DWI, and DCE) and subsequent MRI-(in-bore)-biopsy were retrospectively analyzed. Qualitative DCE evaluation according to PI-RADS v2.1, semi-quantitative (curve type; DCE score according to PI-RADS v1), and quantitative Tofts analyses (Ktrans, kep, and ve) as well as PI-RADS v1 and v2.1 overall classification of 209 lesions (92 PCa, 117 benign lesions) were performed. Of each DCE assessment method, cancer detection, discrimination of csPCa, and localization were assessed and compared to histopathology findings. All DCE analyses (p<0.01-0.05), except ve (p = 0.02), showed significantly different results for PCa and benign lesions in the peripheral zone (PZ) with area under the curve (AUC) values of up to 0.92 for PI-RADS v2.1 overall classification. In the transition zone (TZ) only the qualitative DCE evalulation within PI-RADS (v1 and v2.1) could distinguish between PCa and benign lesions (p<0.01; AUC = 0.95). None of the DCE parameters could differentiate csPCa from non-significant (ns) PCa (p ≥ 0.1). Qualitative analysis of DCE within mpMRI according to PI-RADS version 2.1 showed excellent results regarding (cs)PCa detection. Semi-quantitative and quantitative parameters provided no additional improvements. DCE alone wasn't able to discriminate csPCa from nsPCa.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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