Objectives
Correction of the “partial volume effect” has been an area of great interest in the recent times in quantitative PET imaging and has been mainly studied with count recovery models based ...upon phantoms that incorporate hot spheres in a cold background. The goal of this research study was to establish a similar model that is closer to a biological imaging environment, namely hot spheres/lesions in a warm background and to apply this model in a small cohort of patients.
Methods
A NEMA phantom with six spheres (diameters 1–3.7 cm) was filled with
18
FDG to give sphere:background activity ratios of 8:1, 6:1, and 4:1 for three different acquisitions on a Philips Allegro scanner. The hot sphere SUVmax and the background average SUV were measured for calculation of recovery coefficients (RCs). Using the RCs, the lesion diameters, and the lesion:background ratio, the SUVmax of 64 lesions from 17 patients with biopsy proven lung cancer were corrected.
Results
The RCs versus sphere diameters produced characteristic logarithmic curves for each phantom (RCs ranged from 80% to 11%). From a cohort of 17 patients with biopsy proven lung cancer, 64 lesions combined had a mean SUVmax of 7.0 and size of 2.5 cm. After partial volume correction of the SUVmax of each lesion, the average SUVmax increased to 15.5.
Conclusions
Hot spheres in a warm background more closely resemble the actual imaging situation in a living subject when compared to hot spheres in a cold background. This method could facilitate generation of equipment specific recovery coefficients for partial volume correction. The clinical implications for the increased accuracy in SUV determination are certainly of potential value in oncologic imaging.
Purpose
Transarterial radioembolization (TARE) with yttrium-90 (
90
Y) microspheres is a liver-directed treatment for primary and secondary hepatic malignancies. Personalized dosimetry aims for ...maximum treatment effect and reduced toxicity. We aimed to compare pre-treatment voxel-based dosimetry from
99m
Tc macroaggregated albumin (MAA) SPECT/CT with post-treatment
90
Y PET/CT for absorbed dose values, and to evaluate image quality of
90
Y SiPM-based PET/CT.
Methods
Forty-two patients (28 men, 14 women, mean age: 67 ± 11 years) with advanced hepatic malignancies were prospectively enrolled. Twenty patients were treated with glass and 22 with resin microspheres. Radiation absorbed doses from planning
99m
Tc-MAA SPECT/CT and post-therapy
90
Y PET/CT were assessed.
90
Y PET/CT images were acquired for 20 min and reconstructed to produce 5-, 10-, 15-, and 20-min datasets, then evaluated using the 5-point Likert scale.
Results
The mean administered activity was 3.44 ± 1.5 GBq for glass and 1.62 ± 0.7 GBq for resin microspheres. The mean tumor absorbed doses calculated from
99m
Tc-MAA SPECT/CT and
90
Y PET/CT were 175.69 ± 113.76 Gy and 193.58 ± 111.09 Gy (
P
= 0.61), respectively for glass microspheres; they were 60.18 ± 42.20 Gy and 70.98 ± 49.65 Gy (
P
= 0.37), respectively for resin microspheres. The mean normal liver absorbed doses from
99m
Tc-MAA SPECT/CT and
90
Y PET/CT were 32.70 ± 22.25 Gy and 30.62 ± 20.09 Gy (
P
= 0.77), respectively for glass microspheres; they were 18.33 ± 11.08 Gy and 24.32 ± 15.58 Gy (
P
= 0.17), respectively for resin microspheres. Image quality of
90
Y PET/CT at 5-, 10-, 15-, and 20-min scan time showed a Likert score of 3.6 ± 0.54, 4.57 ± 0.58, 4.84 ± 0.37, and 4.9 ± 0.3, respectively.
Conclusions
99m
Tc-MAA SPECT/CT demonstrated great accuracy for treatment planning dosimetry. SiPM-based PET/CT scanner showed good image quality at 10-min scan time, acquired in one bed position. A PET/CT scan time of 5 min showed acceptable image quality and suffices for dosimetry and treatment verification. This allows for inclusion of
90
Y PET/CT in busy routine clinical workflows. Studies with larger patient cohorts are needed to confirm these findings.
To perform a retrospective review to determine whether maximum standardized uptake values (SUV(max)) from staging 2-deoxy-2- (18)F fluoro-D-glucose (FDG) positron emission tomography/computed ...tomography (PET/CT) studies are associated with outcomes for early-stage non-small-cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT).
Seventy-two medically inoperable patients were treated between October 17, 2003 and August 17, 2007 with SBRT for T1-2N0M0 NSCLC. SBRT was administered as 60 Gy in 3 fractions, 50 Gy in 5 fractions, or 50 Gy in 10 fractions using abdominal compression and image-guided SBRT. Cox proportional hazards regression was performed to determine whether PET SUV(max) and other variables influenced outcomes: mediastinal failure (MF), distant metastases (DM), and overall survival (OS).
Biopsy was feasible in 49 patients (68.1%). Forty-nine patients had T1N0 disease, and 23 had T2N0 disease. Median SUV(max) was 6.55 (range, 1.5-21). Median follow-up was 16.9 months (range, 0.1-37.9 months). There were 3 local failures, 8 MF, 19 DM, and 30 deaths. Two-year local control, MF, DM, and OS rates were 94.0%, 10.4%, 30.1%, and 61.3%, respectively. In univariate analysis, PET/CT SUV(max), defined either as a continuous or dichotomous variable, did not predict for MF, DM, or OS. On multivariable analysis, the only predictors for overall survival were T1 stage (hazard ratio = 0.331 95% confidence interval, 0.156-0.701, p = 0.0039) and smoking pack-year history (hazard ratio = 1.015 95% confidence interval, 1.004-1.026, p = 0.0084).
Pretreatment PET SUV(max) did not predict for MF, DM, or OS in patients treated with SBRT for early-stage NSCLC.
Purpose
Hypoxia is an important factor influencing tumor progression and treatment efficacy. The aim of this study was to investigate the repeatability of hypoxia PET imaging with
18
FHX4 in ...patients with head and neck and lung cancer.
Methods
Nine patients with lung cancer and ten with head and neck cancer were included in the analysis (NCT01075399). Two sequential pretreatment
18
FHX4 PET/CT scans were acquired within 1 week. The maximal and mean standardized uptake values (SUV
max
and SUV
mean
) were defined and the tumor-to-background ratios (TBR) were calculated. In addition, hypoxic volumes were determined as the volume of the tumor with a TBR >1.2 (HV
1.2
). Bland Altman analysis of the uptake parameters was performed and coefficients of repeatability were calculated. To evaluate the spatial repeatability of the uptake, the PET/CT images were registered and a voxel-wise comparison of the uptake was performed, providing a correlation coefficient.
Results
All parameters of
18
FHX4 uptake were significantly correlated between scans: SUV
max
(
r
= 0.958,
p
< 0.001), SUV
mean
(
r
= 0.946,
p
< 0.001), TBR
max
(
r
= 0.962,
p
< 0.001) and HV
1.2
(
r
= 0.995,
p
< 0.001). The relative coefficients of repeatability were 15 % (SUV
mean
), 17 % (SUV
max
) and 17 % (TBR
max
). Voxel-wise analysis of the spatial uptake pattern within the tumors provided an average correlation of 0.65 ± 0.14.
Conclusion
Repeated hypoxia PET scans with
18
FHX4 provide reproducible and spatially stable results in patients with head and neck cancer and patients with lung cancer.
18
FHX4 PET imaging can be used to assess the hypoxic status of tumors and has the potential to aid hypoxia-targeted treatments.
e17049 Background: 177Lu–PSMA is a radiolabeled small molecule that delivers β radiation to cells expressing prostate-specific membrane antigen (PSMA). It has been approved for use in metastatic ...castration-resistant prostate cancer (mCPRC) in 3/2022, based on VISION study. The Food and Drug Administration (FDA) label for 177Lu–PSMA requires prior therapy with an androgen receptor pathway inhibitor (ARPI) and taxane-based chemotherapy as well as presence of at least one PSMA-positive tumor with uptake greater than normal liver and no PSMA-negative lesions on a PSMA positron emission tomography (PET) scan. In the VISION study, PSMA PET was performed within 4 weeks of therapy start. Further, patient received either 177Lu–PSMA plus protocol permitted standard of care (SOC), including ARPI, or SOC alone. Given the relatively recent approval of this therapy, real-world familiarity with administration of this agent may not be optimal. Methods: A retrospective analysis of 25 patients with mCRPC who received 177Lu–PSMA therapy since 3/2022 at the University of California Irvine (24/25) and Hoag Hospital (1/25) was performed. Multiple variables were analyzed and compared to the FDA label for this agent as well as design of the VISION study. Results: All patients in this study had received an ARPI and at least one taxane chemotherapy prior to 177Lu–PSMA. A PSMA-PET scan was obtained prior to 177Lu–PSMA therapy in all patients. The timing of the scan was within 4 weeks of starting 177Lu–PSMA therapy in only 5/25 (20.0%) patients. The average time from PSMA PET scan to 177Lu–PSMA therapy start was 66 days range: 18 - 326 days. None of the PSMA PET scan reports included a baseline liver standardized uptake value (SUV) or mentioned whether any lesions were non PSMA-avid. All reports provided SUV values for some, but not all, PSMA-avid lesions. The average maximum SUV of the most PSMA-avid lesion noted on the reports was 34.7. All PSMA PET scans were retrospectively reviewed by a nuclear medicine specialist and the average maximum SUV of the most PSMA-avid lesion on re-review was 42.0 (p <0.05). During 177Lu–PSMA therapy, co-administration of ARPI occurred in 10/24 (23.8%) of patients. Conclusions: This study highlights the differences in quality metrics between patients who received 177Lu–PSMA therapy in a real-world practice setting compared to the FDA label for this agent and VISION study design. Differences included lack of uniform PSMA PET scan reporting, timing of obtaining pre-treatment PSMA PET imaging, and co-administration of ARPI. Development of institutional algorithms around administration of 177Lu–PSMA therapy may be needed.
In reply to Gates and Salem Yu, Naichang; Srinivas, Shyam M; Difilippo, Frank P ...
International journal of radiation oncology, biology, physics,
06/2013, Letnik:
86, Številka:
2
Journal Article
An antigen binding fragment (BFab) derived from a tumor-associated mucin 1–sialoglycotope antigen (CA6) targeting antibody (huDS6) was engineered. We synthesized a companion diagnostic positron ...emission tomography (PET) tracer by radiolabeling BFab with 64Cu to measure CA6 expression on cancer tissues prior to anti-human CA6 (huDS6-DM4 antibody-drug conjugate) therapy for ovarian and breast cancer patients. After chemotherapy, the ovarian patient received PET scan with 18F-2-fluoro-2-deoxyglucose (18FFDG: 10 mCi), followed by 64Cu-DOTA-BFab (64CuBFab; 5.5 mCi) 1 week later for PET scanning of CA6 expression and subsequent surgery. The breast cancer patient was treated with chemotherapy before primary tumor resection and subsequent 18FFDG-PET scan. 4 weeks later the patient received of 64CuBFab (11.7 mCi) for CA6 PET scan. Whole body 18FFDG-PET of the breast cancer patient indicated FDG-avid tumor metastases to the liver, bilateral hila and thoracic spine, but no uptake was observed for the ovarian patient. Each patient was also imaged by PET/CT with 64CuBFab at 1 and 24 hours after tracer administration. The 64CuBFab tracer was well tolerated by both patients without adverse effects, and no significant tracer uptake was observed in both patients. Immunohistochemistry (IHC) data indicated CA6 expressions were weak to intermediate and matched with the 64CuBFab-PET signals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract Objective The objective of the study is to examine the utility of positron emission tomography (PET) for staging and restaging after treatment of paranasal sinus carcinomas. Study design ...Retrospective data review was done. Subjects and methods Patients selected underwent PET for sinonasal neoplasms from 2003 to 2008 at a tertiary care referral center. Results Seventy-seven scans were reviewed from 31 patients. The pathologies included olfactory neuroblastoma (n = 9), squamous cell carcinoma (n = 6), sinonasal undifferentiated carcinoma (n = 6), sinonasal melanoma (n = 6), and minor salivary gland carcinomas (n = 4). The positive predictive value of studies performed for restaging at the primary, neck, and distant sites were 56%, 54%, and 63%; negative predictive values were 93%, 100%, and 98%, respectively. During restaging, 32% of patients were accurately upstaged secondary to neck or distant site involvement. Conclusion Positron emission tomography serves as a useful adjunct to conventional imaging in the management of sinonasal malignancies. Negative studies are effective in predicting absence of disease as seen in the consistently high-negative predictive values. Positive studies need to be viewed cautiously given the high rate of false-positive studies. When viewed in conjunction with clinical examination, endoscopic assessment, and focused biopsies, they may effectively result in a more accurate assessment of the extent of disease.
Optical Doppler tomography (ODT) is an imaging modality that takes advantage of the short coherence length of a broad-band light sources to perform micrometer-scale, cross-sectional imaging of tissue ...structure and blood flow dynamics simultaneously. The authors review in this paper the principal of ODT and its applications. Results from in vitro and in vivo model studies demonstrated that ODT can map the blood flow velocity profile with high spatial resolution in scattering medium. ODT detection mechanisms are illustrated using Monte Carlo simulations. The application of ODT to image brain hemodynamics is demonstrated. Finally, the authors discuss the limitations of the current technology and application of a phase resolved technique to improve image speed and quality.
PDF
