The virtual reference radiologist: comprehensive AI assistance for clinical image reading and interpretation

OBJECTIVES

Large language models (LLMs) have shown potential in radiology, but their ability to aid radiologists in interpreting imaging studies remains unexplored. We investigated the effects of a state-of-the-art LLM (GPT-4) on the radiologists' diagnostic workflow.

MATERIALS AND METHODS

In this retrospective study, six radiologists of different experience levels read 40 selected radiographic [n = 10], CT [n = 10], MRI [n = 10], and angiographic [n = 10] studies unassisted (session one) and assisted by GPT-4 (session two). Each imaging study was presented with demographic data, the chief complaint, and associated symptoms, and diagnoses were registered using an online survey tool. The impact of Artificial Intelligence (AI) on diagnostic accuracy, confidence, user experience, input prompts, and generated responses was assessed. False information was registered. Linear mixed-effect models were used to quantify the factors (fixed: experience, modality, AI assistance; random: radiologist) influencing diagnostic accuracy and confidence.

RESULTS

When assessing if the correct diagnosis was among the top-3 differential diagnoses, diagnostic accuracy improved slightly from 181/240 (75.4%, unassisted) to 188/240 (78.3%, AI-assisted). Similar improvements were found when only the top differential diagnosis was considered. AI assistance was used in 77.5% of the readings. Three hundred nine prompts were generated, primarily involving differential diagnoses (59.1%) and imaging features of specific conditions (27.5%). Diagnostic confidence was significantly higher when readings were AI-assisted (p > 0.001). Twenty-three responses (7.4%) were classified as hallucinations, while two (0.6%) were misinterpretations.

CONCLUSION

Integrating GPT-4 in the diagnostic process improved diagnostic accuracy slightly and diagnostic confidence significantly. Potentially harmful hallucinations and misinterpretations call for caution and highlight the need for further safeguarding measures.

CLINICAL RELEVANCE STATEMENT

Using GPT-4 as a virtual assistant when reading images made six radiologists of different experience levels feel more confident and provide more accurate diagnoses; yet, GPT-4 gave factually incorrect and potentially harmful information in 7.4% of its responses.

(+)-[18F]Flubatine as a novel α4β2 nicotinic acetylcholine receptor PET ligand-results of the first-in-human brain imaging application in patients with β-amyloid PET-confirmed Alzheimer's disease and healthy controls

PURPOSES

We present the first in-human brain PET imaging data of the new α4β2 nicotinic acetylcholine receptor (nAChR)-targeting radioligand (+)-[18F]Flubatine. Aims were to develop a kinetic modeling-based approach to quantify (+)-[18F]Flubatine and compare the data of healthy controls (HCs) and patients with Alzheimer's disease (AD); to investigate the partial volume effect (PVE) on regional (+)-[18F]Flubatine binding; and whether (+)-[18F]Flubatine binding and cognitive test data respective β-amyloid radiotracer accumulation were correlated.

METHODS

We examined 11 HCs and 9 mild AD patients. All subjects underwent neuropsychological testing and [11C]PiB PET/MRI examination. (+)-[18F]Flubatine PET data were evaluated using full kinetic modeling and regional as well as voxel-based analyses.

RESULTS

With 270-min p.i., the unchanged parent compound amounted to 97 ± 2%. Adequate fits of the time-activity curves were obtained with the 1 tissue compartment model (1TCM). (+)-[18F]Flubatine distribution volume (binding) was significantly reduced in bilateral mesial temporal cortex in AD patients compared with HCs (right 10.6 ± 1.1 vs 11.6 ± 1.4, p = 0.049; left 11.0 ± 1.1 vs 12.2 ± 1.8, p = 0.046; one-sided t tests each). PVE correction increased not only (+)-[18F]Flubatine binding of approximately 15% but also standard deviation of 0.4-70%. Cognitive test data and (+)-[18F]Flubatine binding were significantly correlated in the left anterior cingulate, right posterior cingulate, and right parietal cortex (r > 0.5, p < 0.05 each). In AD patients, (+)-[18F]Flubatine binding and [11C]PiB standardized uptake value ratios were negatively correlated in several regions; whereas in HCs, a positive correlation between cortical (+)-[18F]Flubatine binding and [11C]PiB accumulation in the white matter was found. No adverse event related to (+)-[18F]Flubatine occurred.

CONCLUSION

(+)-[18F]Flubatine is a safe and stable PET ligand. Full kinetic modeling can be realized by 1TCM without metabolite correction. (+)-[18F]Flubatine binding affinity was high enough to detect group differences. Of interest, correlation between white matter β-amyloid PET uptake and (+)-[18F]Flubatine binding indicated an association between white matter integrity and availability of α4β2 nAChRs. Overall, (+)-[18F]Flubatine showed favorable characteristics and has therefore the potential to serve as α4β2 nAChR-targeting PET ligand in further clinical trials.

Cognitive correlates of α4β2 nicotinic acetylcholine receptors in mild Alzheimer's dementia

In early Alzheimer's dementia, there is a need for PET biomarkers of disease progression with close associations to cognitive dysfunction that may aid to predict further cognitive decline and neurodegeneration. Amyloid biomarkers are not suitable for that purpose. The α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) are widely abundant in the human brain. As neuromodulators they play an important role in cognitive functions such as attention, learning and memory. Post-mortem studies reported lower expression of α4β2-nAChRs in more advanced Alzheimer's dementia. However, there is ongoing controversy whether α4β2-nAChRs are reduced in early Alzheimer's dementia. Therefore, using the recently developed α4β2-nAChR-specific radioligand (-)-18F-flubatine and PET, we aimed to quantify the α4β2-nAChR availability and its relationship to specific cognitive dysfunction in mild Alzheimer's dementia. Fourteen non-smoking patients with mild Alzheimer's dementia, drug-naïve for cholinesterase therapy, were compared with 15 non-smoking healthy controls matched for age, sex and education by applying (-)-18F-flubatine PET together with a neuropsychological test battery. The one-tissue compartment model and Logan plot method with arterial input function were used for kinetic analysis to obtain the total distribution volume (VT) as the primary, and the specific binding part of the distribution volume (VS) as the secondary quantitative outcome measure of α4β2-nAChR availability. VS was determined by using a pseudo-reference region. Correlations between VT within relevant brain regions and Z-scores of five cognitive functions (episodic memory, executive function/working memory, attention, language, visuospatial function) were calculated. VT (and VS) were applied for between-group comparisons. Volume of interest and statistical parametric mapping analyses were carried out. Analyses revealed that in patients with mild Alzheimer's dementia compared to healthy controls, there was significantly lower VT, especially within the hippocampus, fronto-temporal cortices, and basal forebrain, which was similar to comparisons of VS. VT decline in Alzheimer's dementia was associated with distinct domains of impaired cognitive functioning, especially episodic memory and executive function/working memory. Using (-)-18F-flubatine PET in patients with mild Alzheimer's dementia, we show for the first time a cholinergic α4β2-nAChR deficiency mainly present within the basal forebrain-cortical and septohippocampal cholinergic projections and a relationship between lower α4β2-nAChR availability and impairment of distinct cognitive domains, notably episodic memory and executive function/working memory. This shows the potential of (-)-18F-flubatine as PET biomarker of cholinergic α4β2-nAChR dysfunction and specific cognitive decline. Thus, if validated by longitudinal PET studies, (-)-18F-flubatine might become a PET biomarker of progression of neurodegeneration in Alzheimer's dementia.

Radiation dosimetry of the α4β2 nicotinic receptor ligand (+)-[18F]flubatine, comparing preclinical PET/MRI and PET/CT to first-in-human PET/CT results

BACKGROUND

Both enantiomers of [18F]flubatine are new radioligands for neuroimaging of α4β2 nicotinic acetylcholine receptors with positron emission tomography (PET) exhibiting promising pharmacokinetics which makes them attractive for different clinical questions. In a previous preclinical study, the main advantage of (+)-[18F]flubatine compared to (-)-[18F]flubatine was its higher binding affinity suggesting that (+)-[18F]flubatine might be able to detect also slight reductions of α4β2 nAChRs and could be more sensitive than (-)-[18F]flubatine in early stages of Alzheimer's disease. To support the clinical translation, we investigated a fully image-based internal dosimetry approach for (+)-[18F]flubatine, comparing mouse data collected on a preclinical PET/MRI system to piglet and first-in-human data acquired on a clinical PET/CT system. Time-activity curves (TACs) were obtained from the three species, the animal data extrapolated to human scale, exponentially fitted and the organ doses (OD), and effective dose (ED) calculated with OLINDA.

RESULTS

The excreting organs (urinary bladder, kidneys, and liver) receive the highest organ doses in all species. Hence, a renal/hepatobiliary excretion pathway can be assumed. In addition, the ED conversion factors of 12.1 μSv/MBq (mice), 14.3 μSv/MBq (piglets), and 23.0 μSv/MBq (humans) were calculated which are well within the order of magnitude as known from other 18F-labeled radiotracers.

CONCLUSIONS

Although both enantiomers of [18F]flubatine exhibit different binding kinetics in the brain due to the respective affinities, the effective dose revealed no enantiomer-specific differences among the investigated species. The preclinical dosimetry and biodistribution of (+)-[18F]flubatine was shown and the feasibility of a dose assessment based on image data acquired on a small animal PET/MR and a clinical PET/CT was demonstrated. Additionally, the first-in-human study confirmed the tolerability of the radiation risk of (+)-[18F]flubatine imaging which is well within the range as caused by other 18F-labeled tracers. However, as shown in previous studies, the ED in humans is underestimated by up to 50 % using preclinical imaging for internal dosimetry. This fact needs to be considered when applying for first-in-human studies based on preclinical biokinetic data scaled to human anatomy.

Relationship between pulmonary rehabilitation and care dependency in COPD

The aims of this study were to explore care dependency before and after pulmonary rehabilitation (PR) in patients with COPD (n=331) and to compare the response to PR between care dependent and independent patients. At baseline, 85 (25.7%) patients had a Care Dependency Scale (CDS) score ≤68 points and were considered as care dependent. CDS scores of these patients improved after PR (p<0.001). After PR, CDS score of 38 (44.7%) patients with a baseline CDS score ≤68 points increased to >68 points. Patients with a baseline CDS score ≤68 points or >68 points showed after PR a comparable improvement in COPD Assessment Test, Hospital Anxiety and Depression Scale and 6-min walk distance (all p<0.05).

TRIAL REGISTRATION NUMBER

NTR3416 (The Netherlands).

Internal dose assessment of (-)-18F-flubatine, comparing animal model datasets of mice and piglets with first-in-human results

(-)-(18)F-flubatine is a promising tracer for neuroimaging of nicotinic acetylcholine receptors (nAChRs), subtype α4β2, using PET. Radiation doses after intravenous administration of the tracer in mice and piglets were assessed to determine the organ doses (ODs) and the effective dose (ED) to humans. The results were compared with subsequent clinical investigations in human volunteers.

METHODS

Twenty-seven female CD1 mice (weight ± SD, 28.2 ± 2.1 g) received intravenous injection of 0.75 ± 0.33 MBq of (-)-(18)F-flubatine. Up to 240 min after injection, 3 animals per time point were sacrificed and the organs harvested, weighed, and counted in a γ counter to determine mass and activity, respectively. Furthermore, whole-body PET scans of 5 female piglets (age ± SD, 44 ± 3 d; weight ± SD, 13.7 ± 1.7 kg) and 3 humans (2 men and 1 woman; age ± SD, 59.6 ± 3.9 y; weight ± SD, 74.3 ± 3.1 kg) were obtained up to 236 min (piglets) and 355 min (humans) after injection of 186.6 ± 7.4 and 353.7 ± 10.2 MBq of (-)-(18)F-flubatine, respectively, using a PET/CT scanner. The CT was used for delineation of the organs. Exponential curves were fitted to the time-activity-data, and time and mass scales were adapted to the human anatomy. The ODs were calculated using OLINDA/EXM (version 1.0); EDs were calculated with the tissue-weighting factors of ICRP103.

RESULTS

After the injection of (-)-(18)F-flubatine, there were no adverse or clinically detectable pharmacologic effects in any of the subjects. The highest activities after injection were found in the kidneys, urinary bladder, and liver. The urinary bladder receives the highest OD in all investigated species, followed by the kidneys and the liver for animals and humans, respectively. On the basis of mouse, piglet, and human kinetic data, the projected human ED of (-)-(18)F-flubatine was estimated to be 12.5 μSv/MBq in mice, 14.7 ± 0.7 μSv/MBq in piglets, and 23.4 ± 0.4 μSv/MBq in humans.

CONCLUSION

As has been demonstrated for other PET radiotracers, preclinical (i.e., animal-derived) dosimetry underestimates the ED to humans, in the current case of (-)-(18)F-flubatine by 34%-44%.

Evaluation of metabolism, plasma protein binding and other biological parameters after administration of (-)-[(18)F]Flubatine in humans

INTRODUCTION

(-)-[(18)F]Flubatine is a PET tracer with high affinity and selectivity for the nicotinic acetylcholine α4β2 receptor subtype. A clinical trial assessing the availability of this subtype of nAChRs was performed. From a total participant number of 21 Alzheimer's disease (AD) patients and 20 healthy controls (HCs), the following parameters were determined: plasma protein binding, metabolism and activity distribution between plasma and whole blood.

METHODS

Plasma protein binding and fraction of unchanged parent compound were assessed by ultracentrifugation and HPLC, respectively. The distribution of radioactivity (parent compound+metabolites) between plasma and whole blood was determined ex vivo at different time-points after injection by gamma counting after separation of whole blood by centrifugation into the cellular and non-cellular components. In additional experiments in vitro, tracer distribution between these blood components was assessed for up to 90min.

RESULTS

A fraction of 15%±2% of (-)-[(18)F]Flubatine was found to be bound to plasma proteins. Metabolic degradation of (-)-[(18)F]Flubatine was very low, resulting in almost 90% unchanged parent compound at 90min p.i. with no significant difference between AD and HC. The radioactivity distribution between plasma and whole blood changed in vivo only slightly over time from 0.82±0.03 at 3min p.i. to 0.87±0.03 at 270min p.i. indicating the contribution of only a small amount of metabolites. In vitro studies revealed that (-)-[(18)F]Flubatine was instantaneously distributed between cellular and non-cellular blood parts.

DISCUSSION

(-)-[(18)F]Flubatine exhibits very favourable characteristics for a PET radiotracer such as slow metabolic degradation and moderate plasma protein binding. Equilibrium of radioactivity distribution between plasma and whole blood is reached instantaneously and remains almost constant over time allowing both convenient sample handling and facilitated fractional blood volume contribution assessment.

Fully automated radiosynthesis of both enantiomers of [18F]Flubatine under GMP conditions for human application

A fully automatized radiosynthesis of (+)- and (-)-[(18)F]Flubatine ((+)- and (-)NCFHEB) by means of a commercially available synthesis module (TRACERlab FX FN) under GMP conditions is reported. Radiochemical yields of 30% within an overall synthesis time of 40 min were achieved in more than 70 individual syntheses. Specific activities were approximately 3000 GBq/μmol and radiochemical purity was determined to be at least 97%.

Apoptosis, proliferation and inflammatory infiltration in ANCA-positive glomerulonephritis

AIMS

Antineutrophil cytoplasmic antibodies (ANCA) are detected in most patients with crescentic glomerulonephritis and necrotizing small vessel vasculitis. ANCA cause renal inflammation and proliferation. Apoptosis is necessary for resolution of inflammation. We studied apoptosis, apoptosis-regulating proteins, proliferation and infiltration with ANCA target antigen containing neutrophils and monocytes in renal biopsies from ANCA patients and disease controls.

METHODS

Skin biopsies from patients with leukocytoclastic vasculitis (n=6) and renal biopsies from patients with ANCA vasculitis (n=10), ANCA-negative crescentic glomerulonephritis (CGN, n=7), mesangio-proliferative GN (n=6), post-streptococcal GN (PSGN, n=4), diabetic nephropathy (n=6) and minimal change nephropathy (MCNP, n=6) were evaluated by immunohistochemistry. Biopsies were stained for apoptosis (TdT-mediated UTP nick-end labeling, TUNEL), proliferation (Ki-67), neutrophils (NP 57), and monocytes (KP 1). We also evaluated Fas and Bcl-2 expression.

RESULTS

Apoptosis was common in leukocytoclastic vasculitis skin biopsies, but was rare in renal biopsies. ANCA-positive NCGN showed the lowest apoptosis rate, similar to MCNP and diabetic nephropathy. The highest apoptosis rate was seen in PSGN. The highest glomerular Bcl-2 expression was present in ANCA-positive biopsies. The Bcl-2/TUNEL ratio was significantly increased in ANCA-positive necrotizing crescentic glomerulonephritis (NCGN) compared to ANCA-negative CGN and PSGN. When proliferation (Ki-67) and apoptosis were expressed as a ratio, we observed the highest index in biopsies from patients with ANCA-positive NCGN because of their low apoptosis rates. Finally, the glomerular inflammatory infiltrate in ANCA-positive NCGN showed a high percentage of neutrophils.

CONCLUSIONS

These preliminary results suggest an imbalance between apoptosis and proliferation, favoring proliferation, in renal biopsies from ANCA-positive NCGN patients.

Partizipative Entscheidungsfindung PEF) mit chronischen Schmerzpatienten

Fibromyalgia syndrome (FMS) is an exemplary condition of chronic widespread pain that is difficult to control and often leads to frustration and resignation on the part of both the patient and the doctor. Shared decision making (SDM) could be a means to facilitate doctor-patient interaction and might therefore influence therapeutic decisions taken. We conducted a prospective study to evaluate the effects of SDM with FMS patients. We developed a communication train-ing program for physicians and a computer-based information tool on FMS for patients. The study included 133 FMS patients. Intervention group I (IG I) was treated by communication-trained doctors and had access to a computer-based information tool on FMS,intervention group II (IG II) was treated by standard doctors and received the information tool, and the control group (CG) was treated by standard doctors and got no additional information. All three groups we-re offered the same evidence-based treatment options for FMS. Patients of the IGs were more willing to become involved in exercise, to enroll in integrated group therapy for FMS patients (IGTF), and to take analgesics. Patients of the CG preferred anti-depressants. More patients from IG II and CG opted for relaxation techniques. Patients in IG I and IG II choose significantly more therapeutic options than patients in the CG. SDM is one means to increase FMS patients' readiness for treatment. Especially the element of providing sufficient medical information seems to account for this effect. The readiness to enroll in physical activities, to take analgesics, and to participate in psychotherapeutic elements was most likely to be raised through SDM.

PowderSolve– a complete package for crystal structure solution from powder diffraction patterns

Powder diffraction techniques are becoming increasingly popular as tools for the determination of crystal structures. The authors of this paper have developed a software package, namedPowderSolve, to solve crystal structures from experimental powder diffraction patterns and have applied this package to solve the crystal structures of organic compounds with up to 18 variable degrees of freedom (defined in terms of the positions, orientations, and internal torsions of the molecular fragments in the asymmetric unit). The package employs a combination of simulated annealing and rigid-body Rietveld refinement techniques to maximize the agreement between calculated and experimental powder diffraction patterns. The agreement is measured by a full-profile comparison (using theRfactorRwp). As an additional check at the end of the structure solution process, accurate force-field energies may be used to confirm the stability of the proposed structure solutions. To generate the calculated powder diffraction pattern, lattice parameters, peak shape parameters and background parameters must be determined accurately before proceeding with the structure solution calculations. For this purpose, a novel variant of the Pawley algorithm is proposed, which avoids the instabilities of the original Pawley method. The successful application and performance ofPowderSolvefor crystal structure solution of 14 organic compounds of differing complexity are discussed.

Amperometric detection of heavy metal ions in ion pair chromatography at an array of water/nitrobenzene micro interfaces

A novel amperometric detector for heavy metal ions has been developed and successfully applied for ion pair chromatography. The detector is based on the electrochemical transfer of the metal ions across an array of water/nitrobenzene micro interfaces. The ion transfer is facilitated by the neutral ionophores methylenebis(diphenylphosphineoxide) and methylenebis(di- phenylphosphinesulfide). More than eight metals are separated in less than 15 min on an RP18 column using octyl sulfonate as ion pair reagent. For the heavy metals, the limits of decision are 19(Pb(2+)), 9(Zn(2+)), 9l (Co(2+)), 8(Cd(2+)) and 1.6(Mn(2+)) microg/L. The applicability of the new method for water samples is demonstrated.

Investigations on preileal digestion of starch from grain, potato and manioc in horses

In this study preileal starch digestibility of starchy feeds (oats, corn, barley, potatoes, manioc) was determined in seven jejunofistulated horses. The grains were fed whole (oats, corn), rolled (oats, barley), crushed, ground and expanded (corn); the potatoes were fresh, the manioc rolled. Ground corn was also fed in combination with amylase. The feeds were fed partly isolated or in combination with alfalfa meal or hay (Table 1). At least four horses with a cannula in the terminal jejunum were used for each diet. Two meals per day were offered at 12 h intervals. The starch intake was mostly about 2 g/kg bw/meal, except one period with oats (3.9 g starch/kg bw) and with expanded corn (1.4 g/kg bw). Jejunal chyme was postprandially collected 11 times (from 1st to the 11th h after the morning meal for 15 min). Starch was determined polarimetrically. The preileal digestibility of starch was calculated by the marker method (chronic oxide 0.25% DM) and by estimating the total jejunoileal chyme flow during 12 h postprandially extrapolating the sample volume from the 15 min sampling periods. The results of both methods agreed quite well. Preileal digestibility of oat starch (80-90%) was (independent of doses or preparation or of the combination with hay, Table 4) significantly higher than that of whole or crushed corn (30%) or barley (26%). Grinding of corn significantly increased preileal digestibility to 51%, expanding to 90%. The addition of amylase improved digestion of ground corn by 10% (absolute). The preileal digestibility of potato or manioc was less than 10%. Individual factors in the horse (chewing intensity, amylase activity) had also considerable influence on preileal starch digestibility.

Chronic myofascial pain: management by low-output helium-neon laser therapy

Therapeutic benefits of low-output helium-neon laser therapy have not been established, but laser therapy has been suggested as an effective means of treating many acute and chronic musculoskeletal pain syndromes. Although not released for general clinical use by the FA, the helium-neon laser has been promoted to physical therapists and athletic trainers as potentially useful for the treatment of pain syndromes. In particular, it has been proposed that it may be more effective than conventional measures such as medication and conventional physical therapy in the treatment of myofascial pain syndromes (fibrositis, fibromyalgia). The citations in the literature include only case reports. Sixty-two patients were treated by using acupuncture points. Two sessions of five treatments were given six weeks apart. A crossover double-blind technique was used in the treatments. The clinical responses were assessed using portions of the McGill Pain Questionnaire. No statistical difference between the treatment and the placebo groups could be determined.

The design and synthesis of mimetics of peptide beta-turns

The synthesis of an 11 membered ring bis-lactam, a system which is designed as a conformationally restricted mimetic of type I and type II beta-turns is described. Computer assisted molecular modeling was used to compare the predicted low energy conformers of the turn mimetic with idealized type I and type II turn structures. Initial computational analysis indicates that the basic ring structure will provide an excellent foundation for the development of a varieity of beta-turn mimetics.