68Ga-DOTATOC-PET/CT is a well-established method for detecting and targeting the volume definition of meningiomas prior to radiotherapy. Moreover, there is evidence that this method is able to detect meningiomas with higher sensitivity than the goldstandard MRI. Since the hybrid PET/MRI scanner became available in the past few years, the next stage of development could consequently evolve by evaluating the feasibility of a hybrid PET/MRI scanner using 68Ga-DOTATOC for detecting meningiomas.
Fifteen patients received 68Ga-DOTATOC-PET/CT (0.5 h post injection [p.i.]) followed by PET/MRI 2 hours p.i. Both investigations were analyzed separately and then compared with respect to image quality, detection of intracranial meningiomas, and radiotracer uptake values (RUVs). In addition, ratios between radiotracer uptake in meningiomas and pituitary glands were compared between both PET/CT and PET/MRI.
Overall, 33 intracranial meningiomas were detected. All were visible with high contrast in both PET/CT and PET/MRI. 68Ga-DOTATOC-PET/MRI provided flawless image quality without artefacts. Calculated RUV in meningiomas, as well as the ratios of RUVs in meningiomas to those of pituitary glands, were higher in PET/CT. As a result, meningiomas can be distinguished from pituitary glands better in early images.
68Ga-DOTATOC-PET/MRI provided flawless image quality and presented an ideal combination of high sensitivity/specificity (PET) and the best possible morphological visualization of meningiomas (MRI). In addition, excellent detection of meningiomas is already possible at 0.5 hours p.i. Later images do not improve the distinction between pituitary gland and adjacent meningiomas. However, RUVs need to be carefully compared between both imaging modalities.
hybrid imaging; meningioma; MRI; 68Ga-DOTATOC; PET/CT; PET/MRI; somatostatin receptor
Staging of lung cancer is typically performed with fluorodeoxyglucose-positron emission tomography-computed tomography (FDG-PET/CT); however, false positive PET scans can occur due to inflammatory disease. The CT scan is used for anatomic registration and attenuation correction. Herein, we evaluated x-ray attenuation (XRA) within nodes on CT and correlated this with the presence of malignancy in an orthotopic lung cancer model in rats.
1×106 NCI-H460 cells were injected transthoracically in six National Institutes of Health nude rats and six animals served as controls. After two weeks, animals were sacrificed; lymph nodes were extracted and scanned with a micro-CT to determine their XRA prior to histologic analysis.
Median CT density in malignant lymph nodes (n=20) was significantly higher than benign lymph nodes (n=12; P = 0.018). Short-axis diameter of metastatic lymph nodes was significantly different than benign nodes (3.4 mm vs. 2.4 mm; P = 0.025). Area under the curve for malignancy was higher for density-based lymph node analysis compared with size measurements (0.87 vs. 0.7).
XRA of metastatic mediastinal lymph nodes is significantly higher than benign nodes in this lung cancer model. This suggests that information on nodal density may be useful when used in combination with the results of FDG-PET in determining the likelihood of malignant adenopathy.
Radiotherapy is the main therapeutic approach besides surgery of localized prostate cancer. It relies on risk stratification and exact staging. This report analyses the potential of [68Ga]Glu-urea-Lys(Ahx)-HBED-CC (68Ga-PSMA-11), a new positron emission tomography (PET) tracer targeting prostate-specific membrane antigen (PSMA) for prostate cancer staging and individualized radiotherapy planning.
A cohort of 57 patients with prostate cancer scanned with 68Ga-PSMA-11 PET/CT for radiotherapy planning was retrospectively reviewed; 15 patients were at initial diagnosis and 42 patients at time of biochemical recurrence. Staging results of conventional imaging, including bone scintigraphy, CT or MRI, were compared with 68Ga-PSMA ligand PET/CT results and the influence on radiotherapeutic management was quantified.
68Ga-PSMA ligand PET/CT had a dramatic impact on radiotherapy application in the presented cohort. In 50.8 % of the cases therapy was changed.
The presented imaging technique of 68Ga-PSMA PET/CT could be a key technology for individualized radiotherapy management in prostate cancer.
Prostate cancer; 68Ga-PSMA ligand PET/CT; Radiotherapy planning; Individualized radiotherapy
PET/CT with the PSMA ligand is a powerful new method for the early detection of nodal metastases in patients with biochemical relapse. The purpose of this retrospective investigation was to evaluate the volume and dimensions of nodes identified by Glu-urea-Lys-(Ahx)-[68Ga(HBED-CC)] (68Ga-PSMA-11) in the setting of recurrent prostate cancer.
All PET/CT images were acquired 60 ± 10 min after intravenous injection of 68Ga-PSMA-11 (mean dose 176 MBq). In 21 patients with recurrent prostate cancer and rising PSA, 49 PSMA-positive lymph nodes were identified. Using semiautomated lymph node segmentation software, node volume and short-axis and long-axis dimensions were measured and compared with the maximum standardized uptake values (SUVmax). Round nodes greater than or equal to 8 mm were considered positive by morphological criteria alone. The percentage of nodes identified by elevated SUVmax but not by conventional morphological criteria was determined.
The mean volume of 68Ga-PSMA-11-positive nodes was 0.5 ml (range 0.2 – 2.3 ml), and the mean short-axis diameter was 5.8 mm (range 2.4 – 13.3 mm). In 7 patients (33.3 %) with 31 PSMA-positive nodes only 11 (36 %) were morphologically positive based on diameters >8 mm on CT. In the remaining 14 patients (66.7 %), 18 (37 %) of PSMA positive lymph nodes had short-axis diameters <8 mm with a mean short-axis diameter of 5.0 mm (range 2.4 – 7.9 mm). Thus, in this population, 68Ga-PSMA-11 PET/CT detected nodal recurrence in two-thirds of patients who would have been missed using conventional morphological criteria.
68Ga-PSMA-11 PET/CT is more sensitive than CT based 3D volumetric lymph node evaluation in determining the node status of patients with recurrent prostate cancer, and is a promising method of restaging prostate cancers in this setting.
68Ga-PSMA-11 PET/CT; Recurrent prostate cancer; Lymph node evaluation; Lymph node metastasis
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise throughout the year 2014 to the high quality and success of this journal.
Both 18F-fluorodihydroxyphenylalanine (18F-DOPA) and 18F-fluoroethyltyrosine (18F-FET) have already been used successfully for imaging of brain tumors. The aim of this study was to evaluate differences between these 2 promising tracers to determine the consequences for imaging protocols and the interpretation of findings.
Forty minutes of dynamic PET imaging were performed on 2 consecutive days with both 18F-DOPA and 18F-FET in patients with recurrent low-grade astrocytoma (n = 8) or high-grade glioblastoma (n = 8). Time-activity-curves (TACs), standardized uptake values (SUVs) and compartment modeling of both tracers were analyzed, respectively.
The TAC of DOPA-PET peaked at 8 minutes p.i. with SUV 5.23 in high-grade gliomas and 10 minutes p.i. with SUV 4.92 in low-grade gliomas. FET-PET peaked at 9 minutes p.i. with SUV 3.17 in high-grade gliomas and 40 minutes p.i. with SUV 3.24 in low-grade gliomas. Neglecting the specific uptake of DOPA into the striatum, the tumor-to-brain and tumor-to-blood ratios were higher for DOPA-PET. Kinetic modeling demonstrated a high flow constant k1 (mL/ccm/min), representing cellular internalization through AS-transporters, for DOPA in both high-grade (k1 = 0.59) and low-grade (k1 = 0.55) tumors, while lower absolute values and a relevant dependency from tumor-grading (high-grade k1 = 0.43; low-grade k1 = 0.33) were observed with FET.
DOPA-PET demonstrates superior contrast ratios for lesions outside the striatum, but SUVs do not correlate with grading. FET-PET can provide additional information on tumor grading and benefits from lower striatal uptake but presents lower contrast ratios and requires prolonged imaging if histology is not available in advance due to a more variable time-to-peak.
brain tumor; DOPA; FET; positron emission tomography
Since the introduction of positron emission tomography (PET) imaging with 68Ga-PSMA-HBED-CC (=68Ga-DKFZ-PSMA-11), this method has been regarded as a significant step forward in the diagnosis of recurrent prostate cancer (PCa). However, published data exist for small patient cohorts only. The aim of this evaluation was to analyse the diagnostic value of 68Ga-PSMA-ligand PET/CT in a large cohort and the influence of several possibly interacting variables.
We performed a retrospective analysis in 319 patients who underwent 68Ga-PSMA-ligand PET/CT from 2011 to 2014. Potential influences of several factors such as prostate-specific antigen (PSA) level and doubling time (DT), Gleason score (GSC), androgen deprivation therapy (ADT), age and amount of injected tracer were evaluated. Histological verification was performed in 42 patients after the 68Ga-PSMA-ligand PET/CT. Tracer uptake was measured in 901 representative tumour lesions.
In 82.8 % of the patients at least one lesion indicative of PCa was detected. Tumor-detection was positively associated with PSA level and ADT. GSC and PSA-DT were not associated with tumor-detection. The average maximum standardized uptake value (SUVmax) of tumour lesions was 13.3 ± 14.6 (0.7–122.5). Amongst lesions investigated by histology, 30 were false-negative in 4 different patients, and all other lesions (n = 416) were true-positive or true-negative. A lesion-based analysis of sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) revealed values of 76.6 %, 100 %, 91.4 % and 100 %. A patient-based analysis revealed a sensitivity of 88.1 %. Of 116 patients available for follow-up, 50 received local therapy after 68Ga-PSMA-ligand PET/CT.
68Ga-PSMA-ligand PET/CT can detect recurrent PCa in a high number of patients. In addition, the radiotracer is highly specific for PCa. Tumour detection is positively associated with PSA and ADT. 68Ga-PSMA-ligand PET/CT can help delay systemic therapy of PCa.
Electronic supplementary material
The online version of this article (doi:10.1007/s00259-014-2949-6) contains supplementary material, which is available to authorized users.
Prostate cancer; PET/CT; Positron emission tomography; PSMA; FMCH; FECH
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise throughout the year 2013 to the high quality and success of this journal.
Positron emission tomography (PET) with choline tracers has found widespread use for the diagnosis of prostate cancer (PC). However, choline metabolism is not increased in a considerable number of cases, whereas prostate-specific membrane antigen (PSMA) is overexpressed in most PCs. Therefore, a 68Ga-labelled PSMA ligand could be superior to choline tracers by obtaining a high contrast. The aim of this study was to compare such a novel tracer with standard choline-based PET/CT.
Thirty-seven patients with biochemical relapse of PC [mean prostate-specific antigen (PSA) 11.1 ± 24.1 ng/ml, range 0.01–116] were retrospectively analysed after 18F-fluoromethylcholine and 68Ga-PSMA PET/CT within a time window of 30 days. Radiotracer uptake that was visually considered as PC was semi-quantitatively analysed by measuring the maximum standardized uptake values (SUVmax) of the scans acquired 1 h after injection of 68Ga-PSMA complex solution (median 132 MBq, range 59–263 MBq) and 18F-fluoromethylcholine (median 237 MBq, range 114–374 MBq), respectively. In addition, tumour to background ratios were calculated.
A total of 78 lesions characteristic for PC were detected in 32 patients using 68Ga-PSMA PET/CT and 56 lesions were detected in 26 patients using choline PET/CT. The higher detection rate in 68Ga-PSMA PET/CT was statistically significant (p = 0.04). In five patients no lesion was found with both methods. All lesions detected by 18F-fluoromethylcholine PET/CT were also seen by 68Ga-PSMA PET/CT. In 68Ga-PSMA PET/CT SUVmax was clearly (>10 %) higher in 62 of 78 lesions (79.1 %) and the tumour to background ratio was clearly (>10 %) higher in 74 of 78 lesions (94.9 %) when compared to 18F-fluoromethylcholine PET/CT.
68Ga-PSMA PET/CT can detect lesions characteristic for PC with improved contrast when compared to standard 18F-fluoromethylcholine PET/CT, especially at low PSA levels.
Electronic supplementary material
The online version of this article (doi:10.1007/s00259-013-2525-5) contains supplementary material, which is available to authorized users.
Prostate cancer; PET/CT; Positron emission tomography; PSMA; Choline
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise throughout the year 2012 to the high quality and success of this journal.
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise throughout the year 2011 to the high quality and success of this journal.
Liposarcoma frequently occurs in the retroperitoneum and lower extremities, accounting for 20% of all mesenchymal malignancies. Liposarcomas vary by histology and can be classified into four types. Those four types are well differentiated, myxoid/round cell, pleomorphic and dedifferentiated. Due to retroperitoneal location of this tumor, it is expected to affect the kidney position. Renography has provided a unique tool for noninvasive evaluation of various functional parameters e.g. relative renal function. Most renography studies are carried out using the posterior view, under the assumption that the depths of both kidneys are similar so that the radiotracer counts in the region of interest will be attenuated to the same extent. Errors in estimation of the relative renal function may arise if the kidneys are at different depths e.g. secondary to a pushing tumor. Geometric mean imaging from combined anterior and posterior views helps to overcome this issue. This case shows the impact of geometric mean imaging in the truthful determination of partial function in patients with retroperitoneal liposarcoma.
MAG3; geometric mean; retroperitoneal liposarcoma; renal scan
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise throughout the year 2010 to the high quality and success of this journal.
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise throughout the year 2009 to the high quality and success of this journal.
This article focuses on a relatively new concept in the Internet: “Social networking” and especially on one program that successfully found a unique way to provide a social network for Radiology: Radiolopolis. Radiolopolis (www.Radiolopolis.com) is an international Radiology network to promote education, research and clinical practice in Radiology. What makes this Radiology community unique and special is that the founders of Radiolopolis implemented multiple educational and clinical/practical programs which have been developed over the past years.
Radiology community; Radiology network; social networking; Radiology education; research; training; clinical practice; information exchange; teaching; Radiolopolis
This special issue of the Journal of Radiology Case Reports honors the reviewers who donated their time and expertise to the high quality and success of this journal.