David Schuster

Reproducibility and Reliability of Anti-3-[18F]FACBC Uptake Measurements in Background Structures and Malignant Lesions on Follow-Up PET-CT in Prostate Carcinoma: an Exploratory Analysis

PurposeThe aim of this study is to examine the reproducibility of anti-1-amino-3-[18F]fluorocyclobutane-1-carboxylic acid (anti-3-[18F]FACBC) quantitative measurements in key background structures and untreated malignant lesions.ProceduresRetrospective review of 14 patients who underwent follow-up anti-3-[18F]FACBC positron emission tomography-X-ray computed tomography (PET-CT) for prostate carcinoma recurrence. Standard uptake values (SUV) were measured in both original and follow-up scans in key background structures and untreated malignant lesions. Absolute and percent mean difference in SUV between scans and interclass correlation coefficients (ICC) were also computed.ResultsMean (±SD, range) scan interval was 17.4 months (±7.1, 4–29). %Mean difference in SUVmean was <20 % in background structures with low absolute differences. ICCs were >0.6 except for early-phase blood pool (ICC = 0.4). SUVmax in malignant lesions without interim therapy increased or remained stable over time.ConclusionsDespite variable time interval between scans, FACBC PET-CT demonstrates acceptable reproducibility in key background structures. Untreated malignant lesions showed stable or increased uptake over time. A formal test-retest study is planned.

Incremental benefit of SPECT + CT bone scans over conventional planar and SPECT bone scans in vertebroplasty

Study design: Planar bone scans with SPECT and SPECT + CT were performed in those patients who underwent peri-operative evaluation for vertebroplasty. The scans were evaluated separately to identify the “culprit” vertebra (e) by two readers and their results were analyzed. Objective: Use of planar and SPECT bone scan for identifying the “culprit” vertebra (e) for vertebroplasty is well established. SPECT + CT is a relatively recent imaging tool providing co-registered fused images. Theoretical advantages of SPECT + CT over conventional SPECT imaging needs to be evaluated and documented. Summary of Background Data: Percutaneous stabilization of collapsed vertebra by bone cement has now become a standard procedure. However, it is essential to localize the correct vertebra. Imaging modalities like CT scan provides structural or anatomical information where as bone scan (planar + SPECT images) provides more functional or physiological information. Combination of these two imaging modalities is expected to provide much more than information obtained by any one imaging modality separately. To the best our knowledge, there is no reference available in the literature adopting this approach. Materials and Methods: Two expert readers, blinded to patient history, evaluated the scans. They independently analyzed planar + SPECT only images followed by SPECT/CT fused images with the aim to identify the acutely fractured vertebra for vertebroplasty. Results: Interpretations changed, on average, 50% of the time as a result of the additional information provided by SPECT + CT. SPECT + CT more precisely localizes tracer abnormalities in the vertebra compared to SPECT imaging alone Conclusion: The greatest value of co-registered SPECT + CT bone scan lies in the accurate localization of affected vertebrae in complicated cases of multiple collapsed vertebrae of different ages as well as in the post-vertebroplasty setting

Imaging of Prostate Cancer Using Fluciclovine

Prostate cancer is the most common cancer and the second leading cause of cancer death in men in the United States. Despite high prevalence, diagnosis and surveillance is limited due to indolent biology. Functional imaging techniques improved the ability to detect disease. Amino acids are building blocks of proteins and intracellular transport is upregulated in prostate cancer. Normal biodistribution patterns of fluciclovine include uptake in the liver and pancreas with minimal to no urine excretion, a distinct advantage for prostate cancer imaging. This review provides a detailed overview of the use of F-18 fluciclovine PET in prostate cancer imaging.

A semiautomatic algorithm for three-dimensional segmentation of the prostate on CT images using shape and local texture characteristics.

Prostate segmentation in computed tomography (CT) images is useful for planning and guidance of the diagnostic and therapeutic procedures. However, the low soft-tissue contrast of CT images makes the manual prostate segmentation a time-consuming task with high inter-observer variation. We developed a semi-automatic, three-dimensional (3D) prostate segmentation algorithm using shape and texture analysis and have evaluated the method against manual reference segmentations. In a training data set we defined an inter-subject correspondence between surface points in the spherical coordinate system. We applied this correspondence to model the globular and smoothly curved shape of the prostate with 86, well-distributed surface points using a point distribution model that captures prostate shape variation. We also studied the local texture difference between prostate and non-prostate tissues close to the prostate surface. For segmentation, we used the learned shape and texture characteristics of the prostate in CT images and we used a set of user inputs for prostate localization. We trained our algorithm using 23 CT images and tested it on 10 images. We evaluated the results compared with those of two experts’ manual reference segmentations using different error metrics. The average measured Dice similarity coefficient (DSC) and mean absolute distance (MAD) were 88 ± 2% and 1.9 ± 0.5 mm, respectively. The averaged inter-expert difference measured on the same dataset was 91 ± 4% (DSC) and 1.3 ± 0.6 mm (MAD). With no prior intra-patient information, the proposed algorithm showed a fast, robust and accurate performance for 3D CT segmentation.

Radiologic Assessment of Esophageal Cancer

Esophageal cancer represents the third most common gastrointestinal tract malignancy and sixth most common cause of cancer death worldwide. The majority of esophageal cancers are either squamous cell carcinoma (SCC) or adenocarcinomas. SCC is the most common pathological subtype with a higher incidence in developing countries. Esophageal adenocarcinomas comprise 15 % of all esophageal cancers. Other malignant tumors such as sarcomas, lymphoma, and small cell carcinoma (neuroendocrine tumor) are uncommon. Accurate initial staging of esophageal cancer is required to guide treatment protocols and to estimate prognosis.