Need For Repeat Imaging Research Articles

The overview of imaging protocols for chest CT

Computed Tomography (CT) is a common method of choice in the diagnosis of thoracic diseases. Since CT operates on the principle of ionizing radiation and frequently involves the use of contrast agents, it is crucial to standardize CT protocols to reduce the need for repeat imaging and, consequently, minimize patient exposure to radiation. The selection of a CT protocol primarily depends on the patient’s clinical indications and needs. The main classification of CT protocols distinguishes between the use of contrast agents (CECT) and non-contrast protocols (NCCT). The LDCT protocol is characterized by a low radiation dose and high sensitivity for detecting pulmonary nodules, making it suitable for lung cancer screening. Ultra-LDCT yields satisfactory results in diagnosing pneumonia and pneumothorax. Cine CT enables the assessment of cardiac function throughout the entire cardiac cycle, though it involves a high radiation dose and low temporal resolution. The use of contrast agents is particularly beneficial for differentiating adjacent non-vascular structures, more accurately identifying vascular anatomy, and improving the detection and characterization of pathological lesions. For diagnosing vascular pathologies, CTA is used, while CTPA is essential for diagnosing pulmonary embolism (PE) with high sensitivity and specificity. TRO CT is useful in cases of acute chest pain to rule out emergencies. Dynamic changes in tissue perfusion are monitored with DCE-CT, which is also valuable in tumor diagnostics. In pediatric applications of CT for the chest, it is essential to emphasize the use of the lowest possible radiation dose and contrast agent to minimize risks.

Diagnosing Pneumonia in the Obese: Are Plain Radiographs Enough?

Introduction: The obesity pandemic presents numerous challenges in radiography, including patients exceeding the weight limits of imaging equipment, difficulties in palpating anatomical landmarks and inadequate penetration resulting in inaccurate diagnoses and need for repeat imaging resulting in increased radiation exposure. Pneumonia is a common reason for hospitalization, but identifying an infiltrate on the chest radiograph (CXR) in obese patients can be challenging. Conversely, motion artefacts may be misinterpreted as areas of pneumonia resulting in over-diagnosis and consequently the overuse of antibiotics. This study evaluated the diagnostic utility of CXR for identifying pneumonia in obese patients by comparing it with computed tomography (CT scan) performed within 72 hours. We also evaluated the impact on initiation or discontinuation of antibiotics – a very important aspect of antibiotic stewardship. Methods: All patients admitted between July 2020 and 2022 with a diagnosis of pneumonia who underwent both CXR and chest CT scan within a 72-hour window were included. Patients were divided into two groups obese and non-obese based on BMI. The results were evaluated to determine the concordance between the two modalities in diagnosing pneumonia, as well as its influence on antibiotic therapy. Results: A total of 320 patients were included, with a mean age of 65.3 years. 146 (45.6%) were male, and 174 (54.4%) were female. 202 (63.1%) were classified as obese (BMI > 30). CXR was performed as first modality in 313 (97.8%) cases, while 7 (2.2%) underwent CT scan first. In the obese group the overall concordance between the 2 modalities for diagnosing pneumonia was 67.5%. In the non-obese group the concordance was 80.2% (p < 0 .001). Among the obese patients who underwent CXR first, 11 (5%) had antibiotics discontinued after the CT scan results, while the number was 4 (3%) in the non-obese group. Additionally, 3 patients in the obese group had antibiotics initiated after the CT scan. Conclusions: Obesity poses unique challenges to healthcare facilities and imaging equipment. Diagnosing pneumonia in obese patients using CXR alone may result in over-diagnosis. This may lead to unnecessary antibiotic use and delayed diagnosis of alternate disease, or in some cases, missing a pneumonia and under-treatment. A chest CT scan is more sensitive and may be more helpful to identify a pneumonia accurately in these patients and thus facilitate appropriate antibiotic use.

Association between repeat imaging and readmission in patients with acute ischaemic stroke: a 16-year nationwide population-based study.

This study aims to evaluate such usage patterns and identify factors that may contribute to the need for repeat imaging in acute ischaemic stroke patients and determine the association between repeat imaging and readmission in Taiwan. We searched and analysed data from the Taiwan National Health Insurance Research Database for patients admitted for acute ischaemic stroke between 2002 and 2017. Cases where repeat brain imaging during the initial hospital admission occurred and where patients were readmitted within 30 days following discharge were documented. Of a total of 195 016 patients with new onset ischaemic stroke, 51 798 (26.6%) underwent repeat imaging during their initial admission. Factors associated with repeat brain imaging included younger age, longer hospital stay, use of recombinant tissue plasminogen activator (rt-PA) therapy (odds ratio = 2.10 [95% CI, 1.98-2.22]), more recent year of diagnosis, higher National Institutes of Health Stroke Scale (NIHSS) score, and admission to a hospital offering a higher level of care. Repeat imaging was also associated with an increased risk of ischaemic stroke and all types of stroke readmission. Repeat brain imaging of patients with stroke has increased in recent years, and it is associated with certain factors including age, length of stay, use of rt-PA, hospital level of care, and NIHSS score. It is also associated with increased readmission. Knowledge of the associations of repeat imaging may help clinicians use repeat imaging more carefully and efficaciously.

Incidental deep venous thrombosis diagnosed on lower extremity computed tomography is a rare but clinically impactful finding

BackgroundIn the setting of a known thrombotic event, computed tomography (CT) studies provide reasonable sensitivity for the diagnosis of deep venous thrombosis (DVT). However, the incidence and accuracy of a DVT diagnosis on CT studies not targeted for the detection of DVT are not well described. In addition, the clinical impact of DVTs incidentally identified on CT is unknown. MethodsIn this single-institution retrospective study, we queried all contrasted CT studies of the lower extremities performed over a 10-year period. Regular expressions applied to the radiology reports associated with the CT studies identified studies with positive findings associated with DVT. These selected reports were then manually reviewed to confirm the presence of a DVT. Patient demographics and relevant medical and surgical history were obtained through a chart review. Follow-up information was obtained for 1 year after the incident CT and included treatment course, additional imaging, and adverse events. An incidental DVT was one identified in a patient in whom the DVT was not noted in a prior study and for whom the study indication did not include concern for DVT or pulmonary embolism. ResultsOf 16,637 lower extremity contrasted CT studies queried, 37 study reports identified a DVT. However, only 13 patients had a finding of an incidental DVT (10-year incidence of 0.08%). Among these 13 patients, 11 underwent additional imaging, including 9 who had a subsequent venous duplex and 2 who had subsequent CT studies. Among those with a subsequent duplex, DVT was not identified in eight cases, whereas in one case, DVT was confirmed. Among those with subsequent CT studies, DVT was not identified in one case and was confirmed in one case. Of the 13 patients with incidental DVTs, 3 were initiated on anticoagulation based on their initial CT findings alone. Among these, two did not experience any complications from their DVT or anticoagulation regimen. One did experience major bleeding complications, requiring additional procedures. ConclusionsIncidental DVTs are a rare finding in lower extremity CT studies, noted to occur in only 0.08% of studies. Most patients with incidental DVTs receive additional imaging, with negative findings in 80% of cases. This study identified that 23% of patients were initiated on anticoagulation due to the CT findings, with a 33% rate of significant complications. Currently, a CT venogram is not recommended as a first-line modality for the diagnosis of DVT. However, there is no guidance regarding the need for repeat imaging in patients with incidentally diagnosed lower extremity DVTs identified on CT. Additional study is needed to provide evidence for guideline development.

Abstract TP131: Computed Tomography Perfusion Imaging Patterns Are Similar Before and After Interfacility Transfer of Ischemic Stroke Patients

Background: Large vessel occlusion (LVO) stroke patients are often transferred from regional hospitals to comprehensive stroke centers (CSC) for thrombectomy. The need for repeat imaging at CSCs prior to intervention is unclear. We compared regional hospital and CSC perfusion imaging results for interfacility transfers in a single health system. Methods: We analyzed a cohort of patients in western Michigan who received CT perfusion imaging before and after transfer to a CSC. Perfusion mismatch (MM), core infarct volume (CIV), and favorability of imaging for mechanical thrombectomy (MT) candidacy were compared between the regional and CSC studies. A favorable imaging profile was defined as the presence of LVO, MM volume >10 mL, and MM/CIV ratio of >1.2. Linear regression was used to examine predictors of infarct growth during transfer. Results: Over a 10-month period, 25 patients met inclusion criteria. The median age was 76 (IQR 66-81), 60% were male, median NIHSS was 11 (IQR 2-18), and most patients had occlusion of the internal carotid or middle cerebral arteries (72%). The median time from last known well to initial CT was 250 minutes (IQR 85-620). Regional median MM volume was 52 mL (IQR 8-97), CIV was 0 mL (IQR 0-13), and hypoperfusion intensity ratio (HIR) was 0.25 (IQR 0-0.34). The median time between CTs was 152 minutes (IQR 139-226). The median change in MM volume was -3 mL (IQR -27-3) and median CIV growth rate was 0 mL/hr (IQR 0-2.0). In a multivariable regression model, higher HIR (β=23.2, p=0.012) and minutes between imaging studies (β=0.10, p=0.021) were associated with CIV growth. Sixteen patients (64%) had favorable imaging profiles for MT at the regional hospital. Of these, 15 (93.8%) continued to have a favorable CSC imaging profiles and 9 (56.2%) underwent MT. Of the 9 patients without favorable regional imaging profiles, 1 (11.1%) had a favorable CSC imaging profile and 2 (22.2%) underwent MT. Conclusion: In our sample, regional and CSC perfusion imaging patterns were similar and patients infrequently crossed thresholds for MT candidacy between studies. Initial HIR and longer delays between were independently associated with infarct growth during transfers, however overall infarct growth was very small.

Definitive Chemoradiation Treatment Response Evaluation Using NI-RADS and ctHPVDNA for HPV-Associated Oropharyngeal Squamous Cell Carcinoma

To compare the evaluation of treatment response among patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) treated with definitive (chemo)radiotherapy (CRT). Patients with locally advanced HPV-associated OPSCC treated with definitive radiotherapy (RT) or CRT from 2019 to 2022 at a single institution were reviewed. Patients underwent standard 3-month post-CRT positron emission tomography/computed tomography (PET/CT) scan with or without contrast enhanced CT (CECT) of the head and neck. Plasma circulating tumor HPV DNA (ctHPVDNA) was collected from 2-8 months post-CRT. Equivocal findings on post-CRT imaging prompted repeat evaluation. Imaging response was assessed via NI-RADS (Neck Imaging Reporting and Data System) risk classification and independently reviewed by two board certified radiologists, both blinded to outcomes and ctHPVDNA values. Our cohort of 52 patients included: 87% males; median age 61.5; 63% never smokers, 31% former smokers, 6% current smokers; 44% tonsil primary, 46% base of tongue; 4% T0, 25% T1, 40% T2, 12% T3, 17% T4; 6% N0, 15% N1, 2% N2a, 44% N2b, 25% N2c, 8% N3 (AJCC 7th edition). Concurrent systemic therapy was received in 90%. During this period 71 PET/CTs and 15 CECTs were reviewed for treatment response evaluation; 44% (23/52) patients required additional imaging for equivocal findings; 62 ctHPVDNA blood samples were co-analyzed for treatment evaluation. The highest risk classification score between mucosa, primary, and/or neck site was: 42% NI-RADS 1, 48% NI-RADS 2, and 10% NI-RADS 3. Only patients with locoregional disease recurrence/progression were included for evaluation comparison between imaging and circulating biomarkers. No cancer events occurred without imaging and/or ctHPVDNA detection. Patients with NI-RADS score ≥2 during first post-CRT imaging evaluation more frequently underwent additional imaging (70% vs 30%, p<0.001). NI-RADS risk classification suggested 5 locoregional events (2 true positives, 3 false positives) resulting in 100% sensitivity, 94% specificity, 40% positive predictive value (PPV), and 100% negative predictive value (NPV). Circulating tumor HPV-DNA identified 2 locoregional events (2 true positives, 0 false positives) resulting in 100% sensitivity, 100% specificity, 100% PPV, and 100% NPV. Salvage operations were performed in 2 of 3 patients with false positive disease by NI-RADS classification without any evidence of cancer on final pathology. While limited by the small number of recurrence events in this cohort, ctHPVDNA for HPV-associated OPSCC in conjunction with post-treatment imaging evaluation may limit the need for repeat imaging and unwarranted salvage operations that increase patient worry, morbidity, and financial toxicity. Additional prospective study is warranted.

The cost of perfection: An investigation into the unnecessary rejection of clinically acceptable lateral wrist imaging.

This study illustrates image rejection rates of the lateral wrist x-ray projection at a large, public teaching hospital. Rejected images were evaluated to determine the number of images that needed to be repeated based on the clinical indication. This study highlights the difference in subjective image-repeat decision-making skills existing between radiologists, experienced radiographers and junior radiographers. A retrospective review was conducted of all rejected lateral wrist x-ray images by a panel of three radiologists, three experienced radiographers and six junior radiographers. This review aimed to determine if rejected imaging met the consideration of the clinical indication and assumed appropriate acquisition of an orthogonal projection. A complement of images that had not been rejected were included in the review to create a blinded study. The review demonstrated 85.8% of rejected images were deemed to meet clinical requirements according to radiologists. The experienced radiographers agreed with radiologists regarding 75.3% of images. Junior radiographers agreed with radiologists in 34.2% of cases. Junior radiographers were three times more likely to seek repeat imaging than the radiologists and experienced radiographers. This review demonstrated a lateral wrist projection reject rate of 38.7% with unnecessary repeats according to clinical indications in 85.8% of cases. The review of experienced radiographers was comparable to radiologists; however, the difference in decision-making skills was evident in the junior radiographers. This highlights an alarming trend, should similar results be demonstrated at other health services and indicates an unnecessary burden to clinical practice. Inclusion of clinical reasoning for imaging and the need for repeat imaging is recommended for radiography training programs.

Scheduling Musculoskeletal MRI for Patients With Metallic Hardware: Initial Observations on Decreasing Nondiagnostic and Repeat Examinations at a Multisite Academic Medical Center

As healthcare delivery systems expand to include multiple imaging centers, the process of scheduling patients at the site which best meets their needs continues to become more complex. This quality improvement study aims to create a protocol for patients with metallic hardware at sites with metallic artifact reduction sequences (MARS), increasing the proportion of exams that are diagnostic and reducing the need for repeat imaging. The study population included 322 patients with metallic hardware receiving an MRI at a large multisite healthcare system, divided into a pre-intervention and postintervention cohort. A retrospective PACS query was performed using several keywords in musculoskeletal MRI reports indicating the presence of metallic hardware. This cohort was studied to better understand the existing system failures. An intervention was then implemented by meeting with the departmental RIS and scheduling teams to discuss workflow when scheduling exams for patients with metallic hardware System changes were implemented and results were again studied retrospectively. Before protocol implementation, 134/244 (55%) of exams were performed at sites with metallic artifact reduction sequences which improved to 54 of 78 (69%) in the postintervention cohort (P=0.02). Additionally, the number of exams performed on 3T MRI machines pre-intervention was 14 of 244 (5.7%) compared to 1 of 78 (1.2%) postintervention (P=0.13). The rate of nondiagnostic exams in the preintervention cohort was significantly higher at 41 of 244 (16.8%) when compared to the postintervention cohort at 4 of 78 (5.1% P=0.01). The implementation of this quality improvement protocol reduced the rate of nondiagnostic MSK MRI exams and reduced the inappropriate use of 3T scanners, ultimately saving time and cost for both patients and the health care system.

Reducing radiation exposure and cancer risk for children with scoliosis: EOS the new gold standard

PurposeChildren are exposed to significant radiation doses during the investigation and treatment phases of scoliosis. EOS is a new form of low-dose radiation scan which also yields great image quality. However, currently its use is discouraged in the UK due to higher costs. We aimed to quantify the additional radiation dose and cancer risk.MethodsWe retrospectively reviewed all paediatric cases who received both standing whole spine roentgenograms and EOS scans as part of their investigations for scoliosis during a six-month period. We compared the radiation doses between the two modalities and estimated the additional mean lifetime cancer risk per study.ResultsWe identified 206 children (mean age 14.4) who met the criteria of having both scans. Dose area products (dGycm2) were converted to estimated effective doses (mSv). The total mean doses were 0.68 mSv (PA 0.49 + Lat 0.19) for plain films, and 0.13 mSv (PA 0.08 + Lat 0.04) for EOS scans (p < 0.001). Additional lifetime cancer risk of a plain film was 543% greater than EOS for both sexes (1/10727 versus 1/5827 in males, 1/34483 versus 1/6350 in females).ConclusionThere is approximately 5.4-fold increase in risk of cancer for both boys and girls with roentgenograms over EOS, with girls being the most impacted. This carries a significant impact when considering the need for repeat imaging on additional lifetime malignancy risk in children. In our opinion, EOS dual planar scanning is the new gold standard when X-ray of the whole spine is required.Level of evidence III.

362 The Scarlet Pimpernel: A Case of Polyarteritis Nodosa Presenting as a Left Hepatic Artery Aneurysm

Abstract A 54-year-old female presented to a secondary care hospital with right upper quadrant pain, headache, and persistent dysuria after empirical antibiotic treatment for a urinary tract infection (UTI). Her brother had died under the age of 50 from aneurysmal disease associated with Polyarteritis nodosa (PAN). Urinalysis demonstrated erythrocytes, leucocytes, and nitrites. Her CRP was 428mg/L and ESR 102 mm/hr. CT of the abdomen and pelvis showed reduced attenuation within both kidneys, and she was treated as acute bilateral pyelonephritis with IV antibiotics. Her abdominal pain changed, she described a “pop” in her right hypochondrium, and she developed a new visual disturbance, despite normalisation of her inflammatory markers. This warranted a repeat CT scan which showed an occlusion of the left hepatic artery with surrounding inflammation and an 8mm aneurysm proximally. MRI and CT venogram of the head was unremarkable. PAN was diagnosed on remote consultation with a tertiary care hospital. It is a necrosing vasculitis affecting small to medium sized arteries with aneurysmal dilatation. There is no genetic cause known, though familial cases have been described. The patient was started on treatment dose Dalteparin and transferred to a tertiary hospital. Selective embolisation of the hepatic artery aneurysm was not undertaken, but she was treated with glucocorticoids and cyclophosphamide. This case highlights a rare condition presenting similarly to a treatment refractory UTI requiring multidisciplinary patient care and the need for repeat imaging following clinical deterioration/change.

Robotic ultrasound: An initial feasibility study.

BACKGROUNDPerforming ultrasound during the current pandemic time is quite challenging. To reduce the chances of cross-infection and keep healthcare workers safe, a robotic ultrasound system was developed, which can be controlled remotely. It will also pave way for broadening the reach of ultrasound in remote distant rural areas as well.AIMTo assess the feasibility of a robotic system in performing abdominal ultrasound and compare it with the conventional ultrasound system. METHODSA total of 21 healthy volunteers were recruited. Ultrasound was performed in two settings, using the robotic arm and conventional hand-held procedure. Images acquired were analyzed by separate radiologists. RESULTSOur study showed that the robotic arm model was feasible, and the results varied based on the organ imaged. The liver images showed no significant difference. For other organs, the need for repeat imaging was higher in the robotic arm, which could be attributed to the radiologist’s learning curve and ability to control the haptic device. The doctor and volunteer surveys also showed significant comfort with acceptance of the technology and they expressed their desire to use it in the future. CONCLUSIONThis study shows that robotic ultrasound is feasible and is the need of the hour during the pandemic.

Prostate MRI quality: clinical impact of the PI-QUAL score in prostate cancer diagnostic work-up.

To assess the reproducibility and impact of prostate imaging quality (PI-QUAL) scores in a clinical cohort undergoing prostate multiparametric MRI. PI-QUAL scores were independently recorded by three radiologists (two senior, one junior). Readers also recorded whether MRI was sufficient to rule-in/out cancer and if repeat imaging was required. Inter-reader agreement was assessed using Cohen's κ. PI-QUAL scores were further correlated to PI-RADS score, number of biopsy procedures, and need for repeat imaging. Image quality was sufficient (≥PI-QUAL-3) in 237/247 (96%) and optimal (≥PI-QUAL-4) in 206/247 (83%) of males undergoing 3T-MRI. Overall PI-QUAL scores showed moderate inter-reader agreement for senior (K = 0.51) and junior-senior readers (K = 0.47), with DCE showing highest agreement (K = 0.47). With PI-QUAL-5 studies, the negative MRI calls increased from 50 to 87% and indeterminate PI-RADS-3 rates decreased from 31.8. to 10.4% compared to lower quality PI-QUAL-3 studies. More patients with PI-QUAL scores 1-3 underwent biopsy for negative (47%) and indeterminate probability (100%) MRIs compared to PI-QUAL score 4-5 (30 and 75%, respectively). Ability to rule-in cancer increased with PI-QUAL score, from 50% at PI-QUAL 1-2 to 90% for PI-QUAL 4-5, with a similarly, but greater effect for ruling-out cancer and at a lower threshold, from 0% for scans of PI-QUAL 1-2 to 67.1% for PI-QUAL 4 and 100% for PI-QUAL-5. Higher PI-QUAL scores for image quality are associated with decreased uncertainty in MRI decision-making and improved efficiency of diagnostic pathway delivery. This study demonstrates moderate inter-reader agreement for PI-QUAL scoring and validates the score in a clinical setting, showing correlation of image quality to certainty of decision making and clinical outcomes of repeat imaging and biopsy of low-to-intermediate risk cases.

Perfusion Imaging Collateral Scores Predict Infarct Growth in Non-Reperfused DEFUSE 3 Patients

ObjectiveThis study evaluated the associations of perfusion imaging collateral profiles with radiographic and clinical outcome in late presenting, non-reperfused patients in the DEFUSE 3 clinical trial. MethodsNon-reperfused patients in both treatment arms were included. Baseline ischemic core, Tmax >6s, and Tmax >10s perfusion volumes were calculated with RAPID software; infarct volumes obtained 24 hours after randomization were manually determined from DWI or CT. Substantial infarct growth was defined as a >25mL increase between baseline and 24-hour follow-up. Hypoperfusion Intensity Ratio (HIR) was defined as the proportion of the Tmax >6s lesion with Tmax >10s delay; CBV index was calculated by RAPID from mean CBV values within the Tmax >6s lesion compared to regions of normal CBV. ResultsEighty-four patients were included. ROC analysis showed HIR ≥0.34 (AUC=0.68) and CBV index ≤0.74 (AUC=0.72) optimally predicted substantial infarct growth in follow-up. Median growth was 23.4 versus 73.2mL with HIR threshold of 0.34 (p=0.005), and 24.3 versus 58.7mL with CBV index threshold of 0.74 (p=0.004). If baseline HIR and CBV index were both favorable, median growth was 21.7mL, 40.9mL if one was favorable, and 108.2mL if both were unfavorable (p<0.001). Baseline perfusion profile was not associated with 90-day functional outcome. ConclusionsPerfusion collateral scores forecast infarct growth in late presenting, non-reperfused ischemic stroke patients. These parameters may be useful for guiding transfer decisions, such as need for repeat imaging upon thrombectomy center arrival, and may help identify slow progressing patients more likely to have persistent salvageable ischemic tissue beyond 24 hours.

Evaluation of an Expedited Trauma Transfer Protocol: Right Place, Right Time

Trauma patients may initially be evaluated at non-trauma centers. This may cause a delay in treatment, which could affect their outcome. Additionally, advanced imaging may be performed which may be suboptimal or unnecessary, increase time to transfer, or unable to be viewed when the patient reaches a trauma center increasing the delays to treatment or need for repeat imaging. Rapid identification and transfer to definitive trauma care, minimizing unnecessary delays should be the priority. The trauma registry at a regional Level 1 Adult/Pediatric Trauma center was queried for transferred trauma patients over a 3-y period. A retrospective review was performed. Transferred trauma patients were compared prior to an expedited transfer protocol to after implementation. Demographics, mechanism of injury, injury severity score, computerized tomography scans performed prior to transfer, mortality, hospital and intensive care unit length of stay were compared using bivariate and multivariable regression statistics where appropriate. Transferred trauma patients were identified, 683 in the pre-protocol group and 821 in the post-protocol group, an increase of 16.8%. There were no differences in age, sex, injury severity score, mechanism of injury, mortality, hospital, or intensive care unit length of stay (LOS) throughout the study period. There was a significant decrease in time to transfer (263 min ± 222 versus 227 ± 189, P < 0.001) and computerized tomography scans performed prior to transfer (Head 47% versus 32%, C-spine 36% versus 23%, Thorax 22% versus 16%, Abdomen/Pelvis 24% versus 14%, all P values <0.001 except CT Thorax). Interestingly, the rate of underinsured patients did not increase (21% versus 25%, P=0.05). Risk-adjusted mortality and hospital LOS also did not change during the study period. After implementation of an expedited trauma transfer protocol to a regional Level 1 trauma center there was an associated reduced time of arrival to definitive care and decreased advanced imaging done prior to transfer. However, there was noassociated decrease inmortality or LOS among transferred patients. Further studies examining prehospital transport or hospital choice decisions and subsequent care provided at non-trauma facilities regarding imaging obtained, care rendered, and transfer decisions can be explored.

Evaluation of optimal timing for post-treatment imaging after primary chemoradiotherapy in patients with locally advanced cervical cancer

<h3>Objectives:</h3> Computed tomography (CT) and positron emitted tomography (PET) are used to assess disease response to chemoradiotherapy in locally advanced cervical cancer (LACC), however inconclusive imaging leads to repeat studies, biopsies and added cost. This study aimed to determine optimal timing of post-treatment imaging to optimize detection of residual disease and lower cost without impairing outcomes. <h3>Methods:</h3> We performed a retrospective review of 260 patients (pts) with LACC who received primary chemoradiotherapy or radiation at a single institution between 2009 and 2020. Demographic and clinical information was abstracted from medical records. Pts had at least one post-treatment CT or PET. Primary outcome was accuracy of post-treatment imaging as measured by Area Under the Curve (AUC) with AUC=1 indicating perfect prediction. Pts were grouped by imaging timing: 0-2 months (mos), 2-4 mos, 4-6 mos, or >6 mos. Statistical tests were analysis of variance, chi-square, and Cox proportional hazards. <h3>Results:</h3> 156 pts were included. Median age at diagnosis was 51 yrs, 57% were White, and 35% had private insurance. 78% had squamous histology, 60% had stage III disease, 78% underwent PET and 22% underwent CT. The most common timing for imaging was 2-4 mos (43%), followed by 4-6 mos (22%), >6 mos (22%), and 0-2 mos (13%). A trend toward later imaging was seen in Black pts (37% Black vs 53% White 0-2 mos, 16% Black vs 66% White 2-4 mos, 31% Black vs 57% White 4-6 mos, 46% Black vs 43% White, >6 mos p=0.15). A similar trend occurred comparing uninsured and insured pts (0-2 mos 21% vs 58%, 2-4 mos 28% vs 39%, 4-6 mos 29% vs 37%, >6 mos 31% vs 14%, p=0.08). Post-treatment imaging, regardless of timing, was an accurate indicator of complete response (negative predictive value 99%). Imaging performed between 0-2 mos had the highest AUC, 1.0 (p<0.001), followed by >6 mos (AUC 0.94, p=0.007), 4-6 mos (AUC 0.8, p=0.77), and 2-4 mos (AUC 0.78, <i>ref</i>). Pts with imaging at 2-4 mos were more likely to need repeat imaging (0% (0-2 mos), 22% (2-4 mos), 6% (4-6 mos), and 6% (> 6 mos) [p<0.001]. There was no difference in PFS or OS when comparing imaging timing. <h3>Conclusions:</h3> Though limited by sample size and retrospective design, these data suggest that imaging 2-4 mos post-treatment for LACC leads to increased need for repeat imaging likely due to indeterminate results. We suspect the high performance of 0-2 mo and >6 mo scans were influenced by selection bias; pts who received imaging <2 mos post-treatment likely had clinical signs of persistent disease. Pts in the >6mo group had surpassed the time during which post-treatment effect was evident on PET, and also likely had high concordance with concerning exam findings. While no survival differences were noted, further study is needed to determine timing of post-treatment imaging that optimizes assessment of treatment response while avoiding unnecessary interventions and preserving patient outcomes.

APQS consensus regarding patient shielding during routine radiographic imaging.

Shielding, particularly of the gonads, has been a routine part of diagnostic radiographic imaging for many years. However, recent thinking suggests that such shielding may offer little benefit, and in some cases may actually cause harm, e.g. by obscuring anatomy or paradoxically increasing patient radiation dose secondary to the need for repeat imaging. This thinking has led many institutions in the West to abandon routine shielding. However, in Asia, shielding is still commonplace. It was felt that the Asia-Pacific Forum on Quality and Safety in Medical Imaging (APQS) was an ideal place to discuss the merits of shielding and deliver a pan-Asian consensus. The APQS is an annual meeting that convenes radiation safety and imaging quality experts from all of the major Asian regions. During the 2020 APQS meeting, radiation safety experts from each region discussed their opinions of shielding during a dedicated session. These experts' views were mostly in line with the views of Western radiologists. However, important country specific and cultural factors were noted by each of the experts. A pan-Asian consensus was issued by the forum. It is hoped that this consensus will guide the development of future shielding policies throughout Asia.

The Utility of Adding a Liquid-Nutrient Meal to Aid Interpretation of Small-Bowel Transit Scintigraphy

Small-bowel transit scintigraphy (SBTS) evaluates the accumulation of a radiolabeled meal in the terminal ileal reservoir (TIR) 6 h after ingestion. The location of the TIR may be difficult to determine because anatomic information is limited; for equivocal studies, the patient is asked to return the next day to help determine the TIR location by potential transit into the colon. The purpose of this study was to evaluate whether administration of an additional liquid-nutrient meal (LNM) at 6 h can promote movement of the radiolabeled meal to aid in the interpretation of SBTS and eliminate the need for the patient to return. <b>Methods:</b> This retrospective study reviewed 117 SBTS studies from February 2017 to September 2019. Patients were fed a standardized mixed radiolabeled solid–liquid meal for gastric emptying with SBTS according to Society of Nuclear Medicine and Molecular Imaging practice guidelines. An additional LNM was given at 6 h, and post-LNM images were obtained at least 20 min after the LNM. Two board-certified nuclear medicine physicians independently evaluated all images as equivocal or diagnostic at 6 h. <b>Results:</b> Of the 117 patients (71.8% female; median age, 42.0 y) undergoing SBTS, 37 were equivocal cases at 6 h before the LNM (31.6%; 95% CI, 23.3%–40.9%), compared with 12 equivocal cases after the LNM (10.3%; 95% CI, 5.4%–17.2%). Of the equivocal cases, 25 (69.4%; 95% CI, 51.9%–83.7%) had a definitive result after the LNM, whereas 11 (30.6%; 95% CI, 16.4%–48.1%) remained equivocal and 1 showed rapid transit. Among the 23 patients with gastroparesis, only 13 (57%) responded to the LNM, and none of the 3 patients with irritable bowel syndrome responded. <b>Conclusion:</b> The number of equivocal SBTS cases decreased after administration of an LNM at 6 h, converting to a definitive result. This suggests that with use of an LNM, most patients can complete SBTS in 1 d without the need for repeat imaging at 24 h. Administering an LNM appears to be less effective for patients with gastric disorders. However, the clinical significance remains to be explored, and it is unclear whether such patients have both a gastric and a small-bowel disorder, hence reducing any motility-promoting effect of the LNM.

Use of resources for pediatric cellulitis in hospitalized patients: Evaluating the benefit of imaging and blood cultures

Use of resources for pediatric cellulitis in hospitalized patients: Evaluating the benefit of imaging and blood cultures

S0508 The Effect and Utility of the Liquid Meal, Boost, on Equivocal Small Bowel Transit Studies: A Retrospective Analysis

INTRODUCTION: A small bowel transit study (SBT) evaluates the accumulation of radiolabeled meal in the terminal ileum (TI) and/or colon 6 hours after ingestion. Anatomic information is limited, often requiring that patients return for confirmatory imaging the next day. Given this inconvenience, a high nutrient liquid meal (Boost) can be given to promote passage of the radiolabeled meal into the colon to enhance visualization; however, the utility of this method is unclear. The primary aim of this study was to quantitatively determine if the administration of Boost at 6 hours facilitates visualization of the TI in equivocal cases, producing a definitive study result. METHODS: This retrospective study included 117 patients undergoing SBT studies from 2/2017 to 9/2019. Two board-certified nuclear medicine radiologists independently evaluated all images (pre-Boost and post-Boost) as equivocal or definitive (i.e. normal or abnormal motility). Mutually agreed upon equivocal pre-Boost cases were included in post-Boost analysis. Post-Boost images were obtained 20 minutes after Boost administration. Any discordance was adjudicated by a third reader. The Pearson-Clopper exact method was used to calculate binomial confidence intervals for proportions. The Fisher exact test was employed to test associations between two categorical variables. RESULTS: Of the included patients (71.8% female, median age 42.0 years) that underwent SBT studies, 37 of 117 were equivocal cases pre-Boost (31.6%, 95% CI = 23.3%–40.9%) compared to 12 of 117 (10.3%, 95% CI = 5.4%–17.2%) equivocal cases post-Boost. One case was excluded in subsequent analysis after adjudicator determination. Of the remaining 36 equivocal cases who received Boost, 25 (69.4%, 95% CI = 51.9%–83.7%) had a definitive result after Boost, while 11 (30.6%, 95% CI = 16.4%–48.1%) remained equivocal. IBS, gastroparesis, and non-early satiety cases appear to remain equivocal even after having received Boost (% equivocal: 100% vs. 24.2%, 43.5% vs. 7.7%, 41.7% vs. 8.3% compared to their counterpart; P = 0.023, 0.031, 0.059, respectively). CONCLUSION: The number of equivocal SBT cases was significantly decreased after administration of Boost at 6 hours, with a majority of cases converting to a definitive result. This suggests that some patients can complete the study without the need for repeat imaging. Boost seemed to be less effective for IBS, gastroparesis, and non-early satiety cases. Future studies exploring the cost-efficiency of using Boost should be considered.

Pancreatic duct guidewire placement for biliary cannulation as a risk factor for stone residue after endoscopic transpapillary stone removal

BackgroundRecent improvements in stone extraction implements and apparatus have lessened the complexity of the endoscopic bile duct stone treatment. However, despite confirmation of complete removal, cases of residual stones have been reported, which can result in recurrent biliary symptoms, cholangitis, and pancreatitis and considerably increase cost given the need for repeat imaging and/or procedures. To date, risk factors for residual bile duct stones following endoscopic retrograde cholangiopancreatography (ERCP) extraction have not been thoroughly evaluated. This study retrospectively investigated the incidence and risk factors of residual bile duct stones following extraction via ERCP.MethodsWe retrospectively reviewed all ERCP cases that underwent endoscopic bile duct stone extraction between April 2014 and March 2019. A total of 505 patients were enrolled and evaluated for the incidence and risk factors of residual bile duct stones after ERCP.ResultsThe rate of residual stones was 4.8% (24/505). Residual stones were detected by computed tomography (12/24) or magnetic resonance cholangiopancreatography (12/24). In univariate analyses, a large number of stones (P = 0.01), long procedure time (P = 0.005), and performance of the pancreatic duct guidewire placement method (P-GW) for selective bile duct cannulation (P = 0.01) were the factors involved in residual stones. In multiple logistic regression analysis, performing P-GW was retained as the only independent factor of residual stones (adjusted odds ratio, 3.44; 95% CI, 1.19–9.88; P = 0.02).ConclusionsWhen removing bile duct stones with a pancreatic guidewire in place, paying attention to residual stones is necessary.