Fully integrated PET/MR imaging holds great promise as a novel hybrid imaging modality in oncology and might offer advantages to PET/CT in many instances, especially because of the superior ...soft-tissue contrast of MR imaging, compared with CT. However, lung metastases are a frequent finding in oncologic patients, and for imaging of the lung CT is still the modality of choice. Thus, we prospectively evaluated differences in quality, detection rate, size, and radiotracer uptake of pulmonary lesions in (18)F-FDG PET/CT and PET/MR imaging.
Institutional review board approval and informed consent were obtained. Forty patients (23 men, 17 women; mean age ± SD, 53.2 ± 13.1 y) underwent a single-injection dual-imaging protocol with (18)F-FDG PET/CT and PET/MR imaging. Pulse sequences for the lung included T1-weighted VIBE (volumetric interpolated breath-hold examination) Dixon for attenuation correction and contrast-enhanced VIBE pulse sequences. All patients underwent a diagnostic CT of the chest in deep inspiration, which also served as a standard of reference. Two masked readers assessed in consensus all images randomly concerning quality, detection, standardized uptake value (SUV), and size of pulmonary nodules. Correlations were performed using linear correlation.
Overall, 47 pulmonary lesions (mean size ± SD, 10.0 ± 11.4 mm; range, 2-60 mm) in 25 of 40 patients were detected. The PET datasets of PET/MR imaging and PET/CT revealed 22 of 47 pulmonary lesions with focal (18)F-FDG uptake. SUVs of lung lesions in PET/MR imaging and PET/CT correlated significantly (R = 0.9; P = 0.0001) and showed no significant difference (mean SUV PET/MR imaging, 6.3; PET/CT, 5.1; P = 0.388). There was a significantly lower image quality comparing Dixon and VIBE sequence with CT whereas PET from PET/CT and PET from PET/MR imaging showed the same results (2.8). Dixon images detected 15 of 47 lung lesions whereas VIBE images detected 32 of 47 lesions, respectively. The detection rates for small lung lesions less than 1 cm in diameter (n = 33) of MR imaging was significantly lower, with a detection rate of 9 of 33 for the Dixon sequence and 15 of 33 for the VIBE sequence (P < 0.0001 for VIBE and Dixon sequence). There was a high correlation of pulmonary lesion size of CT versus VIBE (R = 0.97).
PET image quality and detection rate of (18)F-FDG-positive lung lesions in PET/MR imaging is equivalent to PET/CT despite differences in attenuation-correction techniques. Additionally, a high linear correlation coefficient in the SUVs for the PET images from PET/CT and PET/MR imaging was found. The detection rate of lung lesions can be significantly improved by adding a diagnostic contrast-enhanced VIBE sequence to the PET/MR imaging protocol. However, the detection rate of small lung lesions is still inferior, compared with PET/CT with diagnostic CT of the chest.
Integrated PET/MRI systems open exciting possibilities for clinical and research applications. However, compared with PET/CT, PET/MRI is a complex technique resulting in new problems and challenges, ...especially regarding workflow, scan protocols, and data analysis. This complexity applies in particular to examinations in oncology with partial- or whole-body coverage extending over several bed positions. Unlike diagnostic PET/CT, for which the clinical CT protocols can largely be copied from stand-alone CT, the design of a diagnostic MRI protocol for partial- or whole-body coverage is more complex and has to be adapted to the special requirements of PET/MRI to be both time-efficient and comprehensive. Here, we describe basic considerations concerning workflow, imaging protocols, and image analysis for whole-body PET/MRI in oncology, based on our experience with the first integrated PET/MRI scanner. The aim is to fully and optimally make use of the combined PET/MRI measurements in oncology, including identifying and reducing image artifacts as well as optimizing workflow beyond the mere fusion of 2 image datasets.
Abstract PET- and PET/CT using 11 C- and 18 F-labeled choline derivates are increasingly being used for imaging of prostate cancer. The value of PET- and PET/CT with 11 C- and 18 F-labeled choline ...derivates in biochemical recurrence of prostate cancer has been examined in many studies and demonstrates an increasing importance. PET/CT, in comparison to PET, improves especially the lesion localization as well as characterization. Primary prostate cancer can be detected with moderate sensitivity using PET and PET/CT using 11 C- and 18 F-labeled choline derivates—the differentiation between benign prostatic hyperplasia, prostatitis, or high-grade intraepithelial neoplasia (HGPIN) is not always possible. At the present time, 11 C-choline PET/CT is not recommended in the primary setting but may be utilized in clinically suspected prostate cancer with repeatedly negative prostate biopsies, in preparation of a focused re-biopsy. Promising results have been obtained for the use of PET and PET/CT with 11 C- and 18 F-labeled choline derivates in patients with biochemical recurrence. The detection rate of choline PET and PET/CT for local, regional, and distant recurrence in patients with a biochemical recurrence shows a linear correlation with PSA value at the time of imaging and reaches about 75% in patients with PSA > 3 ng/ml. Even at PSA values below 1 ng/ml, the recurrence can be diagnosed with choline PET/CT in approximately one-third of the patients. PET and PET/CT with 11 C- and 18 F-choline derivates can be helpful in the clinical setting for choosing a therapeutic strategy in the sense of an individualized treatment: an early diagnosis of recurrence is crucial to the choice of optimal treatment. Especially important for the choice of treatment is the exact localization of the site of recurrence: local recurrence, recurrence as lymph node metastasis, or systemic recurrence, as it has direct influence on individual therapy. This article reviews the use of PET and PET/CT with 11 C- and 18 F-labeled choline derivates in prostate cancer imaging with special emphasis on patients with biochemical recurrence. We briefly provide an overview of PET tracers for prostate cancer imaging, the rationale of using choline derivatives for prostate cancer imaging and discuss the contribution of choline PET/CT in patients suffering from prostate cancer with an emphasis on recurrent disease. Furthermore, we provide an outlook on future prospects of choline PET/CT imaging for therapy guidance and monitoring in the framework of therapy individualization.
Purpose
To explore circulating tumor cell (CTCs) counts in different stages of prostate cancer (PC) in association with tumor burden, metastatic pattern and conventional serum biomarkers. Overall ...survival (OS) analyses were conducted with respect to optimized CTC cutoff levels.
Methods
Circulating tumor cell counts were assessed in healthy controls (
n
= 15) as well as in locally advanced high risk (LAPC,
n
= 20), metastatic castration resistant (mCRPC,
n
= 40) and taxane-refractory (mTRPC,
n
= 15) PC patients. CTCs were detected using the CellSearch™ System.
Results
In metastatic PC (mPC), CTC counts were significantly increased compared to LAPC (
p
< 0.001). In LAPC, CTCs were at control level (
p
= 0.66). Patients with both bone and visceral lesions revealed the highest median CTC count (
p
= 0.004), whereas patients with sole soft tissue metastases displayed CTC counts comparable to controls (
p
= 0.16). No correlation was observed between CTC counts and osseous tumor burden assessed by bone lesion count (
p
= 0.54) or bone scan index (
p
= 0.81). CTC counts revealed a positive correlation with alkaline phosphatase (
p
< 0.001) and lactate dehydrogenase (
p
< 0.001) as well as a negative association with hemoglobin (
p
= 0.004) and PSA-doubling time (
p
= 0.01). Kaplan–Meier analyses demonstrated a cohort adjusted cutoff level of 3 CTCs with a shorter OS in case of ≥3 CTCs compared to <3 CTCs (
p
= 0.001), a cutoff level applicable in mCRPC (
p
= 0.003) but not in mTRPC patients (
p
= 0.054).
Conclusions
Circulating tumor cell counts are applicable as a prognostic molecular marker, especially in mCRPC patients harboring bone metastases with or without visceral metastases. For clinical practice, mPC patients with elevated CTC counts in combination with short PSA-DT, high alkaline phosphatase and lactate dehydrogenase levels as well as low hemoglobin levels are at high risk of disease progression and limited OS.
Purpose
In this study, the potential contribution of Dixon-based MR imaging with a rapid low-resolution breath-hold sequence, which is a technique used for MR-based attenuation correction (AC) for ...MR/positron emission tomography (PET), was evaluated for anatomical correlation of PET-positive lesions on a 3T clinical scanner compared to low-dose CT. This technique is also used in a recently installed fully integrated whole-body MR/PET system.
Methods
Thirty-five patients routinely scheduled for oncological staging underwent
18
F-fluorodeoxyglucose (FDG) PET/CT and a 2-point Dixon 3-D volumetric interpolated breath-hold examination (VIBE) T1-weighted MR sequence on the same day. Two PET data sets reconstructed using attenuation maps from low-dose CT (PET
AC_CT
) or simulated MR-based segmentation (PET
AC_MR
) were evaluated for focal PET-positive lesions. The certainty for the correlation with anatomical structures was judged in the low-dose CT and Dixon-based MRI on a 4-point scale (0–3). In addition, the standardized uptake values (SUVs) for PET
AC_CT
and PET
AC_MR
were compared.
Results
Statistically, no significant difference could be found concerning anatomical localization for all 81 PET-positive lesions in low-dose CT compared to Dixon-based MR (mean 2.51 ± 0.85 and 2.37 ± 0.87, respectively;
p
= 0.1909). CT tended to be superior for small lymph nodes, bone metastases and pulmonary nodules, while Dixon-based MR proved advantageous for soft tissue pathologies like head/neck tumours and liver metastases. For the PET
AC_CT
- and PET
AC_MR
-based SUVs (mean 6.36 ± 4.47 and 6.31 ± 4.52, respectively) a nearly complete concordance with a highly significant correlation was found (
r
= 0.9975,
p
< 0.0001).
Conclusion
Dixon-based MR imaging for MR AC allows for anatomical allocation of PET-positive lesions similar to low-dose CT in conventional PET/CT. Thus, this approach appears to be useful for future MR/PET for body regions not fully covered by diagnostic MRI due to potential time constraints.
Summary Prostate cancer is one of the most common cancers in men, leading to substantial morbidity and mortality. After definitive therapy with surgery or radiation, many patients have biochemical ...relapse of disease—ie, an increase in their prostate-specific antigen level—which often precedes clinically apparent disease by months or even years. Therefore, imaging of the site and extent of tumour recurrence (local, regional, distant, or a combination) is of great interest. Conventional morphological imaging methods showed limited accuracy for assessment of recurrent prostate cancer; however, in recent years, functional and molecular imaging have offered the possibility of imaging molecular or cellular processes of individual tumours, often with more accuracy than morphological imaging. Hybrid imaging modalities (PET–CT, and single-photon emission CT SPECT–CT) have been introduced that combine functional and morphological data and allow whole-body imaging. Here, we review the contribution of radionuclide imaging and hybrid imaging for assessment of recurrent prostate cancer (local vs regional vs distant disease). We discuss available data on PET–CT and SPECT–CT, and provide an overview of experimental tracers and their preclinical and clinical development. Finally, we present a perspective on the potential of future hybrid magnetic resonance–PET imaging.
Purpose To review the current status and clinical effect of PET-MRI image fusion in the staging of head-and-neck cancer and to show its implications for imaging with future hybrid PET/MRI scanners. ...Materials and Methods We reviewed the current literature in order to provide an overview of the potential of the combination of the anatomic and functional imaging capabilities of magnetic resonance imaging (MRI) and of the potential for molecular and metabolic imaging with Positron emission tomography (PET). The research question was whether these image devices might be of synergistic value. Results PET with 18F-fluorodeoxyglucose has shown promising results for the assessment of lymph node involvement in cancer, the identification of distant metastasis and synchronous and metachronous tumors, and the evaluation of tumor recurrence or carcinoma of an unknown primary. For morphologic imaging, MRI has several advantages compared with computed tomography in the head-and-neck area. This is mainly because of the superior soft tissue contrast and fewer artifacts from dental implants. Moreover, MRI allows functional imaging, such as the assessment of perfusion with dynamic contrast-enhanced MRI. The published data indicate that image fusion should be beneficial in the case of the recurrence of oromaxillofacial cancer and in the evaluation of potential metastatic lymph nodes. However, retrospective image fusion is technically demanding in the head-and-neck area, mainly because of the varied patient positions used for the various scanners and the anatomic complexity of this region. Conclusions Combined PET/MRI scanners might overcome the above-named problems. Both sequential and fully integrated PET/MRI scanners are now available in selected departments, and future studies will show whether hybrid PET/MRI is of greater clinical value than PET/CT and retrospective image fusion techniques.
To evaluate the dependency of the sensitivity of (11)Ccholine positron emission tomography/computed tomography (PET/CT) for detecting and localizing primary prostate cancer (PCa) on tumor ...configuration in the histologic specimen.
Forty-three patients with biopsy-proven PCa were included. They underwent radical prostatectomy within 31 days after (11)Ccholine PET/CT. The transaxial image slices and the histologic specimens were analyzed by comparing the respective slices. Maximum standardized uptake values (SUV(max)) were calculated in each segment and correlated with histopathology. The tumor configuration in the histologic specimen was grouped as: I, unifocal; II, multifocal; III, rind-like shaped; IV, size <5 mm. Data analysis included the investigation of detection of PCa by SUV(max), the assessment of the influence of potential contributing factors on tumor prediction, and the evaluation of whether SUV could discriminate cancer tissue from benign prostate hyperplasia (BPH), prostatitis, HGPIN (high-grade prostate intraepithelial neoplasm), or normal prostate tissue. General estimation equation models were used for statistical analysis.
Tumor configuration in histology was classified as I in 21 patients, as II in 9, as III in 5, and as IV in 8. The prostate segment involved by cancer is identified in 79% of the patients. SUV(max) was located in the same side of the prostate in 95% of patients. Tumor configuration was the only factor significantly negatively influencing tumor prediction (P < 0.001). PCa-SUV(max) (median SUV(max) = 4.9) was not significantly different from BPH-SUV (median SUV(max) = 4.5) and prostatitis-SUV (median SUV(max) = 3.9), P = 0.102 and P = 0.054, respectively.
The detection and localization of PCa in the prostate with (11)Ccholine PET/CT is impaired by tumor configuration. Additionally, in our patient population, PCa tissue could not be distinguished from benign pathologies in the prostate.
Abstract
Background
Parkinsonian symptoms are common adverse effects of antipsychotics. Older adults are particularly vulnerable to drug-induced parkinsonism. Nonetheless, parkinsonian symptoms in ...seniors treated with antipsychotics cannot be straightforwardly attributed to antipsychotic medication. A comprehensive diagnostic workup is necessary in many cases in order to shed light on the cause of such symptoms in this patient population.
Case series
Eight cases of hospitalized depressed older adults with parkinsonian symptoms, who were treated for at least one year with antipsychotics, are reported. Based on neurological consultation, structural brain imaging and Ioflupane (I-123) dopamine transporter (DAT) single photon emission computerized tomography (SPECT), Parkinson’s disease was diagnosed in one case, idiopathic tremor in another, vascular parkinsonism in another one, while in another individual parkinsonian symptoms persisted at 12-month post-discharge follow-up even though his/her symptoms were classified as drug-induced on discharge. In four patients, parkinsonian symptoms were definitely drug-induced and no movement disturbances were reported at follow-up.
Conclusions
Differences in the cause and outcome of parkinsonian symptoms in seniors treated with antipsychotics merit systematic and in-depth study considering the therapeutic and prognostic implications of an accurate detection of the cause of such symptoms. Familiarizing clinical psychiatrists with these differences could pave the way towards approaching seniors with severe, atypical and/or persistent parkinsonian symptoms in a more individualized diagnostic and therapeutic manner, and towards more cautious prescribing of antipsychotics in this age group.
To evaluate the role of hypoxia positron emission tomography (PET) using 18Ffluoroazomycin-arabinoside (FAZA) in head and neck cancer for radiation treatment planning using intensity-modulated ...radiotherapy and dose painting.
Eighteen patients with advanced squamous cell head and neck cancer were included. Both FAZA-PET and axial CT were performed using mask fixation. The data were coregistered using software based on mutual information. Contours of tumor (primary gross tumor volume, GTV/CT-P) and lymph node metastases (GTV/CT-N) were outlined manually, and FAZA standardized uptake values (SUVs) were calculated automatically. The hypoxic subvolume (GTV/PET-FAZA) having at least 50% more FAZA uptake than background (mean SUV) neck muscle tissue was contoured automatically within GTV/CT-P (GTV/PET-FAZA-P) and GTV/CT-N (GTV/PET-FAZA-N).
The median GTV/PET-FAZA-P was 4.6 mL, representing 10.8% (range, 0.7-52%) of the GTV/CT-P. The GTV/PET-FAZA-P failed to correlate significantly with the GTV/CT-P (p = 0.06). The median GTV/PET-FAZA-N was 4.1 mL, representing 8.3% (range, 2.2-51.3%) of the GTV/CT-N. It was significantly correlated with the GTV/PET-N (p = 0.006). The GTV/PET-FAZA-P was located in a single confluent area in 11 of 18 patients (61%) and was diffusely dispersed in the whole GTV/CT-P in 4 of 18 patients (22%), whereas no hypoxic areas were identified in 3 of 18 patients (17%). The GTV/PET-FAZA-N was outlined as a single confluent region in 7 of 18 patients (39%), in multiple diffuse hypoxic regions in 4 of 18 patients (22%), and was not delineated in 7 of 18 patients (39%).
This study demonstrates that FAZA-PET imaging could be used for a hypoxia-directed intensity-modulated radiotherapy approach in head and neck cancer.
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![The Sensitivity of [11C]Cho...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1078-0432/small "The Sensitivity of [11C]Choline PET/CT to Localize Prostate Cancer Depends on the Tumor Configuration")
