Addition of I-MIBG to PRRT (Y-DOTATOC) for Personalized Treatment of Selected Patients with Neuroendocrine Tumors.

Peptide receptor radionuclide therapy (PRRT) is an effective treatment for metastatic neuroendocrine tumors. Delivering a sufficient tumor radiation dose remains challenging because of critical-organ dose limitations. Adding I-metaiodobenzylguanidine (I-MIBG) to PRRT may be advantageous in this regard.

Technical Note: Single time point dose estimate for exponential clearance.

Objective: Although personalized dosimetry may be desirable for radionuclide therapy treatments, the multiple time samples required to determine the total integrated activity puts a burden on patients and clinic resources. The aim of this paper is to demonstrate that when some prior knowledge is known about the tracer kinetic parameters, the total integrated activity (and thus radiation dose) can be estimated from a single time sample.

Methods: Mathematical derivations have been performed to generate equations for the total integrated activity in terms of a single time sample of activity for monoexponential and biexponential clearance.

Y-DOTATOC Dosimetry-Based Personalized Peptide Receptor Radionuclide Therapy.

Pretherapy PET with Y-DOTATOC is considered the ideal dosimetry protocol for Y-DOTATOC therapy; however, its cost, limited availability, and need for infusion of amino acids to mimic the therapy administration limit its use in the clinical setting. The goal of this study was to develop a dosimetric method for Y-DOTATOC using Y-DOTATOC PET/CT and bremsstrahlung SPECT/CT and to determine whether dosimetry-based administered activities differ significantly from standard administered activities. This was a prospective phase 2 trial of Y-DOTATOC therapy in patients with somatostatin receptor-positive tumors.

Effect of fatigue on reading computed tomography examination of the multiply injured patient.

Our goal was to ascertain how fatigue affects performance in reading computed tomography (CT) examinations of patients with multiple injuries. CT images with multiple fractures from a previous study of satisfaction of search (SOS) were read by radiologists after a day of clinical work. Performance in this study with fatigued readers was compared to a previous study in which readers were not fatigued.

The Impact of Fatigue on Satisfaction of Search in Chest Radiography.

Rationale And Objectives: To assess the nature of the satisfaction of search (SOS) effect in chest radiography when observers are fatigued; determine if we could replicate recent findings that have documented the nature of the SOS effect to be due to a threshold shift rather than a change in diagnostic accuracy as in earlier film-based studies.

Materials And Methods: Nearing or at the end of a clinical workday, 20 radiologists read 64 chest images twice, once with and once without the addition of a simulated pulmonary nodule. Half of the images had different types of "test" abnormalities.

Trauma in CT: The Role of Severe Injury on Satisfaction of Search Revised.

Purpose: The satisfaction-of-search (SOS) effect occurs when an abnormality on an image is missed because another is found. The aim of this experiment was to test whether severe distracting fractures control the magnitude of SOS on other fractures when both appear in a single CT image.

Methods: The institutional review board approved this study.

The Influence of a Vocalized Checklist on Detection of Multiple Abnormalities in Chest Radiography.

Rationale And Objectives: Although a checklist has been recommended for preventing satisfaction of search (SOS) errors, a previous research study did not demonstrate that benefit. However, observers in that study had to turn away from the image display to use the checklist. The current study tested a vocalized checklist to avoid this constraint.

Satisfaction of Search in Chest Radiography 2015.

Rationale And Objectives: Two decades have passed since the publication of laboratory studies of satisfaction of search (SOS) in chest radiography. Those studies were performed using film. The current investigation tests for SOS effects in computed radiography of the chest.

Feasibility and advantage of adding (131)I-MIBG to (90)Y-DOTATOC for treatment of patients with advanced stage neuroendocrine tumors.

Background: Peptide receptor radionuclide therapy (PRRT) is an effective form of treatment for patients with metastatic neuroendocrine tumors (NETs). However, delivering sufficient radiation dose to the tumor to result in a high percentage of long-term tumor remissions remains challenging because of the limits imposed on administered activity levels by radiation damage to normal tissues. The goal of this study was to evaluate the dosimetric advantages of adding (131)I meta-iodobenzylguanidine ((131)I-MIBG) to (90)Y DOTA Phe1-Tyr3-octreotide ((90)Y-DOTATOC) in patients with advanced stage midgut NETs.

Improved nuclear medicine uniformity assessment with noise texture analysis.

Unlabelled: Because γ cameras are generally susceptible to environmental conditions and system vulnerabilities, they require routine evaluation of uniformity performance. The metrics for such evaluations are commonly pixel value-based. Although these metrics are typically successful at identifying regional nonuniformities, they often do not adequately reflect subtle periodic structures; therefore, additional visual inspections are required.

Repeatability of gallium-68 DOTATOC positron emission tomographic imaging in neuroendocrine tumors.

Objective: To evaluate the repeatability of gallium-68 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic (DOTA)-D-Phe1-Try3-octreotide (68Ga-DOTATOC) positron emission tomography (PET) in neuroendocrine tumors.

Methods: Five patients with neuroendocrine tumors were imaged with 68Ga-DOTATOC PET twice within 5 days. Maximum and mean standardized uptake values (SUVmax and SUVmean) and kinetic parameters (K-Patlak and K-influx) of target lesions were measured.

Satisfaction of search from detection of pulmonary nodules in computed tomography of the chest.

Rationale And Objectives: We tested whether satisfaction of search (SOS) effects that occur in computed tomography (CT) examination of the chest on detection of native abnormalities are produced by the addition of simulated pulmonary nodules.

Materials And Methods: Two experiments were conducted. In the first experiment, 70 CT examinations, half that demonstrated diverse, subtle abnormalities and half that demonstrated no native lesions, were read by 18 radiology residents and fellows under two experimental conditions: presented with and without pulmonary nodules.

Do long radiology workdays affect nodule detection in dynamic CT interpretation?

Purpose: A previous study demonstrated decreased diagnostic accuracy for finding fractures and decreased ability to focus on skeletal radiographs after a long working day. Skeletal radiographic examinations commonly have images that are displayed statically. The aim of this study was to investigate whether diagnostic accuracy for detecting pulmonary nodules on CT of the chest displayed dynamically would be similarly affected by fatigue.

Toward fully automated processing of dynamic susceptibility contrast perfusion MRI for acute ischemic cerebral stroke.

We developed fully automated software for dynamic susceptibility contrast (DSC) MR perfusion-weighted imaging (PWI) to efficiently and reliably derive critical hemodynamic information for acute stroke treatment decisions. Brain MR PWI was performed in 80 consecutive patients with acute nonlacunar ischemic stroke within 24h after onset of symptom from January 2008 to August 2009. These studies were automatically processed to generate hemodynamic parameters that included cerebral blood flow and cerebral blood volume, and the mean transit time (MTT).

Modeling combined radiopharmaceutical therapy: a linear optimization framework.

In this paper, we investigate a previously proposed mathematical model describing the effects that an innovative combined radiopharmaceutical therapy might have on the delivery of radiation to the tumor and limiting critical organs. While focused on a specific dual agent therapy, this investigation will prove mathematically that for any two therapeutic radiopharmaceuticals with different limiting critical organs the model provides patient specific conditions under which combination therapy is superior to single agent therapy. In addition, this paper outlines general methods for calculating the amounts of administered radioactivity for each drug required to optimize tumor radiation dose.

Nuclear cystometrogram-determined bladder pressure at onset of vesicoureteral reflux predicts spontaneous resolution.

Objectives: The bladder pressure at the onset of reflux may reflect the competence of the ureterovesical junction. The predictive value of the bladder pressure at the onset of vesicoureteral reflux, as measured by nuclear cystometrography, was assessed relative to subsequent reflux resolution.

Methods: Nuclear cystometrograms of 67 children were reviewed to determine the presence of reflux, bladder pressure at the onset of reflux, and bladder volume at the onset of reflux.

Recent advances in SPECT imaging.

SPECT is a rapidly changing field, and the past several years have produced new developments in both hardware technology and image-processing algorithms. At the component level there have been improvements in scintillators and photon transducers as well as a greater availability of semiconductor technology. These devices permit the fabrication of smaller and more compact systems that can be customized for particular applications.

A segmentation-based method for metal artifact reduction.

Rationale And Objectives: We propose a novel segmentation-based interpolation method to reduce the metal artifacts caused by surgical aneurysm clips.

Materials And Methods: Our method consists of five steps: coarse image reconstruction, metallic object segmentation, forward-projection, projection interpolation, and final image reconstruction. The major innovations are 2-fold.

Dual-expressing adenoviral vectors encoding the sodium iodide symporter for use in noninvasive radiological imaging of therapeutic gene transfer.

Introduction: Noninvasive analysis of therapeutic transgene expression is important for the development of clinical translational gene therapy strategies against cancer. To image p53 and MnSOD gene transfer noninvasively, we used radiologically detectable dual-expressing adenoviral vectors with the human sodium iodide symporter (hNIS) as the reporter gene.

Methods: Dual-expressing adenoviral vectors were constructed with hNIS cloned into E3 region and therapeutic genes, either MnSOD or p53, recombined into the E1 region.

Potential increased tumor-dose delivery with combined 131I-MIBG and 90Y-DOTATOC treatment in neuroendocrine tumors: a theoretic model.

Unlabelled: (131)I-Metaiodobenzylguanidine (MIBG) and (90)Y-DOTA-D-Phe1-Tyr3-octreotide (DOTATOC) have been used as radiotherapeutic agents for treating neuroendocrine tumors. The tumor dose delivered by these agents is often insufficient to control or cure the disease. However, these 2 agents used together could potentially increase tumor dose without exceeding the critical organ dose because the dose-limiting tissues are different.

A new software tool for removing, storing, and adding abnormalities to medical images for perception research studies.

Rationale And Objectives: Image perception studies have been difficult to perform using clinical images because of the problems associated with obtaining proven abnormalities and appropriate normal controls. The objective of this research was to develop and evaluate interactive software that allows the seamless removal, archiving and insertion of abnormal areas from computed tomography (CT) lung image sets for use in image perception research.

Materials And Methods: The software tools for removing, archiving, and adding lesions are described in detail.

AAPM Task Group 108: PET and PET/CT shielding requirements.

The shielding of positron emission tomography (PET) and PET/CT (computed tomography) facilities presents special challenges. The 0.511 MeV annihilation photons associated with positron decay are much higher energy than other diagnostic radiations.