The Value of SPECT-CT in Diagnosing Complex Non-Arthritic and Non-Neoplastic Conditions of the Foot and Ankle

Introduction: There is little information on the value of using single photon emission computerized tomography–computed tomography (SPECT-CT) in non-arthritic and non-neoplastic conditions of the foot and ankle (F&A). The vast majority of studies have investigated the role of SPECT-CT in degenerative conditions, bony pathology, and neoplastic conditions. The diagnostic value of SPECT-CT in purely non-arthritic and non-neoplastic conditions, in the absence of other conclusive radiological findings, is yet to be clarified. The aim of this study was to evaluate the value of SPECT-CT in a cohort of patients with complex F&A pathology, in whom diagnostic uncertainty existed after conventional imaging techniques, and to assess its added value in routine clinical practice. Methodology: A retrospective analysis of 297 SPECT-CTs from 2010 to 2017 found 18 SPECT-CTs (age = 16-56 years) performed for non-arthritic F&A pathology. Changes in diagnosis, management, and clinical outcome scores were recorded before and after SPECT-CT imaging. Results: The results demonstrated that the provisional diagnosis was different from the SPECT-CT diagnosis in 10 (56%) out of the 18 patients and led to a modified treatment plan, which was successful in 8 (80%) out of the 10 patients. The post-intervention Manchester Oxford Foot Questionnaire (MOX-FQ) and Visual Analogue Scale (VAS) score improved from 76 ± 18 to 58 ± 24 ( P = .02), and from 72 ± 17 to 49 ± 32 ( P = .01), respectively. The SPECT-CT scan was useful in confirming the provisional diagnosis in the remaining 8 patients where a diagnostic uncertainty existed after conventional imaging techniques. Overall, a total of 15 out of 18 patients (83%) showed an improvement in their symptoms after management led by SPECT-CT diagnosis. Conclusion: Our study highlights the added value of SPECT-CT in patients presenting with non-arthritic and non-neoplastic F&A conditions in which there is diagnostic uncertainty after conventional imaging. In 80% of cases, a change in management driven by the SPECT-CT findings led to a successful outcome. We have found SPECT-CT to be a useful investigative modality in assessing these complex F&A cases. Levels of Evidence: Level IV

P-P46 The use of FDG-PET/CT in the pre-operative staging of pancreatic ductal adenocarcinoma

Background The NICE Quality Standard for Pancreatic Cancer (December 2018) recommends that ‘adults with localised pancreatic cancer on CT(should) have staging using fluorodeoxyglucose positron emission tomography/CT(FDG-PET/CT) before they have surgery, radiotherapy or systemic therapy’. Such FDG-PET/CT staging aims to provide additional information to conventional cross-sectional imaging, thus presenting the most accurate staging of disease. However, the sensitivity and specificity of FDG-PET/CT to deliver relevant additional clinical information must be balanced with potential delays to treatment, and additional cost associated with its use, in the management of a time-critical pathology. Methods Consecutive pancreatic ductal adenocarcinoma(PDAC) patients deemed resectable on conventional imaging, and therefore referred for FDG-PET/CT assessment, were included for analysis. Data were derived from a single tertiary Hepatopancreaticobiliary(HPB) centre between May 2018 and June 2021. Data were collected and analysed from a combination of prospectively-collated electronic databases and paper patient records. Results Of 89 patients analysed, 55(61.7%) patients were male. Primary pancreatic lesions were PET avid in 81 cases(91%). Median time from request to FDG-PET/CT performance was 11 days(Range 1-35). Additional clinical information from FDG-PET/CT was provided in 61(68.5%) patients. Further investigations to assess FDG-PET/CT findings were arranged in 23 patients(25.8%; including liver MRI and EUS), demonstrating that FDG-PET/CT findings were true-positive in 6(26.1%), false-positive in 15(65.2%) and equivocal in 2(8.7%). There was a median delay of 60.5 days(Range 26 to 256) from FDG-PET/CT to surgery in those undergoing additional investigation. In total, a new diagnosis of metastatic/non-resectable disease was made in 14(15.7%) patients, preventing progression to planned operative intervention. Conclusions FDG-PET/CT provided additional information to conventional imaging that led to cancellation of planned operative resection in 14(15.7%) PDAC patients-8 directly and 6 following further investigation. However, there was a median delay of 11 days to FDG-PET/CT and 60.5 days from FDG-PET/CT to surgery in those undergoing additional investigation. Whilst FDG-PET/CT can lead to avoidance of unnecessary surgical intervention in PDAC patients with unsuspected metastatic/non-resectable disease, it can lead to delay, over-investigation, excess cost and anxiety in resectable patients. HPB units should audit their own findings to assess whether the use of FDG-PET/CT should be considered on a standard or selected basis.

CT Texture analysis and CT scores for characterization of fluid collections

Background Texture analysis derived from Computed tomography (CT) might be able to better characterize fluid collections undergoing CT-guided percutaneous drainage treatment. The present study tested, whether texture analysis can reflect microbiology results in fluid collections suspicious for septic focus. Methods Overall, 320 patients with 402 fluid collections were included into this retrospective study. All fluid collections underwent CT-guided drainage treatment and were microbiologically evaluated. Clinically, serologically parameters and conventional imaging findings as well as textures features were included into the analysis. A new CT score was calculated based upon imaging features alone. Established CT scores were used as a reference standard. Results The present score achieved a sensitivity of 0.78, a specificity of 0.69, area under curve (AUC 0.82). The present score and the score by Gnannt et al. (AUC 0.81) were both statistically better than the score by Radosa et al. (AUC 0.75). Several texture features were statistically significant between infected fluid collections and sterile fluid collections, but these features were not significantly better compared with conventional imaging findings. Conclusions Texture analysis is not superior to conventional imaging findings for characterizing fluid collections. A novel score was calculated based upon imaging parameters alone with similar diagnostic accuracy compared to established scores using imaging and clinical features.

Quantitative analysis of metal artifact reduction in total hip arthroplasty using virtual monochromatic imaging and orthopedic metal artifact reduction, a phantom study

Objective To quantify metal artifact reduction using 130 keV virtual monochromatic imaging (VMI) with and without orthopedic metal artifact reduction (O-MAR) in total hip arthroplasty. Methods Conventional polychromatic images and 130 keV VMI of a phantom with pellets representing bone with unilateral or bilateral prostheses were reconstructed with and without O-MAR on a dual-layer CT. Pellets were categorized as unaffected, mildly affected and severely affected. Results When 130 keV VMI with O-MAR was compared to conventional imaging with O-MAR, a relative metal artifact reduction in CT values, contrast-to-noise (CNR), signal-to-noise (SNR) and noise in mildly affected pellets (67%, 74%, 48%, 68%, respectively; p < 0.05) was observed but no significant relative metal artifact reduction in severely affected pellets. Comparison between 130 keV VMI without O-MAR and conventional imaging with O-MAR showed relative metal artifact reduction in CT values, CNR, SNR and noise in mildly affected pellets (92%, 72%, 38%, 51%, respectively; p < 0.05) but negative relative metal artifact reduction in CT values and noise in severely affected pellets (− 331% and -223%, respectively; p < 0.05), indicating aggravation of metal artifacts. Conclusion Overall, VMI of 130 keV with O-MAR provided the strongest metal artifact reduction.

Clinical Utility of Neoadjuvant MRI in Early-Stage Breast Cancer Patients

Background With the increasing use of neoadjuvant treatment (NAT) for patients with early-stage breast cancer (ESBC), adequate clinical staging is essential to inform treatment. While the use of MRI with NAT has been proposed to help with accuracy of pre-treatment clinical staging, its impact in clinical practice remains controversial. Methods A prospective institutional database of patients with ESBC treated with NAT between May 2012 and December 2020 was analyzed in order to compare the management of patients who received an MRI prior to NAT to those who did not. The indications for MRI and correlation of MRI findings to conventional breast imaging were evaluated. The impact of MRI on management was compared between the MRI and non-MRI groups. Results A total of 530 patients met inclusion criteria. Of these, 186 (35.1%) had an MRI and 344 (64.9%) did not. The most frequent indication for MRI was the determination of disease extent (54.5%). Patients who had an MRI prior to neoadjuvant treatment were significantly more likely to be younger (47 years versus 57 years; p<0.001) and have multifocal disease (32.3% versus 22.1%; p<0.05). When compared to conventional imaging, MRI reported a greater extent of disease in the breast (37.6%), more nodal involvement (18.8%) and multifocal disease (15.1%). Additional diagnostic interventions were advised in 52.2% of patients. who underwent MRI. Rates of mastectomies were greater in the MRI group (80.0% versus 58.9%; p<0.05) in addition to more axillary dissections (28.0% versus 17.4%; p<0.01). Rates of locoregional recurrences were low in both groups, with similar disease-free survival outcomes at 5 years. Conclusions MRI identified significantly more disease in contrast to conventional imaging and lead to more aggressive surgical management. Prospective studies evaluating the role of neoadjuvant MRI and its impact on long term outcomes are needed.