Diagnosis of chronic pancreatitis using semi-quantitative MRI features of the pancreatic parenchyma: results from the multi-institutional MINIMAP study

PURPOSE

To determine the diagnostic performance of parenchymal MRI features differentiating CP from controls.

METHODS

This prospective study performed abdominal MRI scans at seven institutions, using 1.5 T Siemens and GE scanners, in 50 control and 51 definite CP participants, from February 2019 to May 2021. MRI parameters included the T1-weighted signal intensity ratio of the pancreas (T1 score), arterial-to-venous enhancement ratio (AVR) during venous and delayed phases, pancreas volume, and diameter. We evaluated the diagnostic performance of these parameters individually and two semi-quantitative MRI scores derived using logistic regression: SQ-MRI Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume).

RESULTS

When compared to controls, CP participants showed a significantly lower mean T1 score (1.11 vs. 1.29), AVR venous (0.86 vs. 1.45), AVR delayed (1.07 vs. 1.57), volume (54.97 vs. 80.00 ml), and diameter of the head (2.05 vs. 2.39 cm), body (2.25 vs. 2.58 cm), and tail (1.98 vs. 2.51 cm) (p < 0.05 for all). AUCs for these individual MR parameters ranged from 0.66 to 0.79, while AUCs for the SQ-MRI scores were 0.82 and 0.81 for Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume), respectively. After propensity-matching adjustments for covariates, AUCs for Models A and B of the SQ-MRI scores increased to 0.92 and 0.93, respectively.

CONCLUSION

Semi-quantitative parameters of the pancreatic parenchyma, including T1 score, enhancement ratio, pancreas volume, diameter and multi-parametric models combining these parameters are helpful in diagnosis of CP. Longitudinal analyses including more extensive population are warranted to develop new diagnostic criteria for CP.

Abstract A037: Predicting pancreatic cancer using artificial intelligence analysis of pancreatic subregions using computed tomography images

Study background: Early detection of pancreatic ductal adenocarcinoma (PDAC) can elevate the current ~10% five-years survival rate of PDAC up to 50%. Accurate stratification of high-risk individuals for PDAC can improve early detection as follow-up screening may assist diagnosis at an early stage. Studies show that the pancreas adopts changes prior to or during the development of cancer due to the underlying biological variations. This study aimed to examine the precancerous changes that occurred within and across pancreatic subregions to help stratify individuals at high risk of developing PDAC. Dataset: In a multi-institute retrospective study, 108 contrast-enhanced CT abdominal scans were collected, consisting of 36 diagnostic scans with established PDAC and observable tumor, 36 pre-diagnostic scans of the same subjects as in the diagnostic group but were obtained up to 3 years before PDAC diagnosis and were deemed ‘normal’ by radiologists, and 36 healthy scans reported with no PDAC signs. Trained radiologists outlined 3 subregions (head, body, tail) in all scans. Also, the subregions in pre-diagnostic scans were classified into high-risk (with cancer underdevelopment) and low-risk (no cancer development) groups by exploring the tumor signs in their corresponding subregions in the diagnostic scans. Experiments and results: Radiomic analysis was performed on all 324 subregions by extracting and analyzing hundreds of morphological and textural features. In a pairwise feature analysis (i.e. between corresponding subregions), the texture of the high-risk subregions in pre-diagnostic scans was found significantly unique and statistically different than that of the low-risk subregions, supporting the study hypothesis. Such textural features are usually too minute and remain obscured when the pancreas is observed as a single structure. The analysis showed that AI can efficiently identify and quantify such predictors. A Naïve Bayes model was then trained using the same data to automatically predict PDAC using the textural features of the pancreatic subregions. In four-fold cross-validation, the model obtained prediction accuracy by correctly classifying pre-diagnostic and healthy CT scans by 88.2% on average, with sensitivity (true positive rate) and specificity (true negative rate) reaching 82.5% and 94.0%, respectively. The results of this preliminary study are promising and encouraging to further validate the model on a larger dataset. The model showed improved results over those produced in our recent study [1] in which the pancreas as a single structure was examined. The prediction based on the proposed model can potentially assist clinicians to undertake specialized screening, diagnosis, and treatment planning accordingly as the tumor structure, symptoms, and drug response for each pancreatic subregion differs a lot. 1. Qureshi et. al, Predicting pancreatic ductal adenocarcinoma using artificial intelligence analysis of pre-diagnostic computed tomography images. Cancer Biomarkers, 33(2), pp.211-217, 2022.

Citation Format: Sehrish Javed, Touseef Ahmad Qureshi, Srinivas Gaddam, Ashley Wachsman, Linda Azab, Vahid Asadpour, Wansu Chen, Bechien Wu, Yibin Xie, Stephen Pandol, Debiao Li. Predicting pancreatic cancer using artificial intelligence analysis of pancreatic subregions using computed tomography images [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A037.

Quantitative MRI of chronic pancreatitis: results from a multi-institutional prospective study, magnetic resonance imaging as a non-invasive method for assessment of pancreatic fibrosis (MINIMAP)

PURPOSE

To determine if quantitative MRI techniques can be helpful to evaluate chronic pancreatitis (CP) in a setting of multi-institutional study.

METHODS

This study included a subgroup of participants (n = 101) enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study (NCT03099850) from February 2019 to May 2021. MRI was performed on 1.5 T using Siemens and GE scanners at seven clinical centers across the USA. Quantitative MRI parameters of the pancreas included T1 relaxation time, extracellular volume (ECV) fraction, apparent diffusion coefficient (ADC), and fat signal fraction. We report the diagnostic performance and mean values within the control (n = 50) and CP (n = 51) groups. The T1, ECV and fat signal fraction were combined to generate the quantitative MRI score (Q-MRI).

RESULTS

There was significantly higher T1 relaxation time; mean 669 ms (± 171) vs. 593 ms (± 82) (p = 0.006), ECV fraction; 40.2% (± 14.7) vs. 30.3% (± 11.9) (p < 0.001), and pancreatic fat signal fraction; 12.2% (± 5.5) vs. 8.2% (± 4.4) (p < 0.001) in the CP group compared to controls. The ADC was similar between groups (p = 0.45). The AUCs for the T1, ECV, and pancreatic fat signal fraction were 0.62, 0.72, and 0.73, respectively. The composite Q-MRI score improved the diagnostic performance (cross-validated AUC: 0.76).

CONCLUSION

Quantitative MR parameters evaluating the pancreatic parenchyma (T1, ECV fraction, and fat signal fraction) are helpful in the diagnosis of CP. A Q-MRI score that combines these three MR parameters improves diagnostic performance. Further studies are warranted with larger study populations including patients with acute and recurrent acute pancreatitis and longitudinal follow-ups.

T1 signal intensity ratio of the pancreas as an imaging biomarker for the staging of chronic pancreatitis

PURPOSE

Our purpose was to validate the T1 SIR (T1 score) as an imaging biomarker for the staging of CP in a large, multi-institutional, prospective study.

METHODS

The prospective study population included 820 participants enrolled in the PROCEED study from nine clinical centers between June 2017 and December 2021. A radiologist at each institution used a standardized method to measure the T1 signal intensity of the pancreas and the reference organs (spleen, paraspinal muscle, liver), which was used to derive respective T1 scores. Participants were stratified according to the seven mechanistic stages of chronic pancreatitis (MSCP 0-6) based on their clinical history, MRCP, and CT findings.

RESULTS

The mean pancreas-to-spleen T1 score was 1.30 in participants with chronic abdominal pain, 1.22 in those with acute or recurrent acute pancreatitis, and 1.03 in definite CP. After adjusting for covariates, we observed a linear, progressive decline in the pancreas-to-spleen T1 score with increasing MSCP from 0 to 6. The mean pancreas-to-spleen T1 scores were 1.34 (MSCP 0), 1.27 (MSCP 1), 1.21 (MSCP 2), 1.16 (MSCP 3), 1.18 (MSCP 4), 1.12 (MSCP 5), and 1.05 (MSCP 6) (p < 0.0001). The pancreas-to-liver and pancreas-to-muscle T1 scores showed less linear trends and wider confidence intervals.

CONCLUSION

The T1 score calculated by SIR of the pancreas-to-spleen shows a negative linear correlation with the progression of chronic pancreatitis. It holds promise as a practical imaging biomarker in evaluating disease severity in clinical research and practice.

Venous bullet embolism to the right ventricle: Case report and review of management

Intravascular missile emboli to the right heart should be retrieved surgically if the risk of surgical complication due to sternotomy and cardiotomy is low. Endovascular retrieval is another possible method of extraction to be considered.

Feasibility and safety study of 22-gauge endoscopic ultrasound (EUS) needles for portal vein sampling in a swine model

Background and study aims  Endoscopic ultrasound (EUS) has been used for portal vein sampling in patients with pancreaticobiliary cancers for enumerating circulating tumor cells but is not yet a standard procedure. Further evaluation is needed to refine the methodology. Therefore, we evaluated the feasibility and safety of 19-gauge (19G) versus a 22-gauge (22 G) EUS fine-needle aspiration needles for portal vein sampling in a swine model. Methods  Celiotomy was performed on two farm pigs. Portal vein sampling occurred transhepatically. We compared 19 G and 22 G needles coated interiorly with saline, heparin or ethylenediaminetetraacetic acid (EDTA). Small- (10 mL) and large- (25 mL) volume blood collections were evaluated. Two different collection methods were tested: direct-to-vial and suction syringe. A bleeding risk trial for saline-coated 19 G and 22 G needles was performed by puncturing the portal vein 20 times. Persistent bleeding after 3 minutes was considered significant. Results  All small-volume collection trials were successful except for 22 G saline-coated needles with direct-to-vial method. All large-volume collection trials were successful when using suction syringe; direct-to-vial method for both 19 G and 22 G needles were unsuccessful. Collection times were shorter for 19 G vs. 22 G needles for both small and large-volume collections ( P  < 0.05). Collection times for saline-coated 22 G needles were longer compared to heparin/EDTA-coated ( P  < 0.05). Bleeding occurred in 10 % punctures with 19 G needles compared to 0 % with 22 G needles. Conclusion  The results of this animal study demonstrate the feasibility and the safety of using 22 G needles for portal vein sampling and can form the basis for a pilot study in patients.

A phase 1 study of veliparib, a PARP-1/2 inhibitor, with gemcitabine and radiotherapy in locally advanced pancreatic cancer

Background

Locally advanced pancreatic cancer (LAPC) has a dismal prognosis with current treatment modalities and one-third of patients die from local progression of disease. Preclinical studies with orthotopic PC demonstrated dramatic synergy between radiotherapy (RT) and the poly(ADP-ribose) polymerase-1/2 inhibitor (PARPi), veliparib. We conducted a phase I trial of gemcitabine, radiotherapy and dose-escalated veliparib in LAPC.

Methods

This was a single institution investigator-initiated open-label, single-arm phase 1 clinical trial (NCT01908478). Weekly gemcitabine with daily IMRT and veliparib dose escalated using a Bayesian adaptive design were administered in treatment naïve LA or borderline resectable PC. The primary end point was identification of the MTD. Secondary endpoints included efficacy, characterization of PAR levels using ELISA, DDR alterations with targeted next generation sequencing and transcriptome analysis, tumor mutation burden (TMB) and microsatellite instability (MSI) status.

Findings

Thirty patients were enrolled. The MTD of veliparib was 40 mg BID with gemcitabine 400 mg/m² and RT (36 Gy/15 fractions). Sixteen DLTs were identified in 12 patients. Grade ≥ 3 adverse events included lymphopenia (96%) and anemia (36%). Median OS for all patients was 15 months. Median OS for DDR pathway gene altered and intact cases was 19 months (95% CI: 6.2–27.2) and 14 months (95% CI: 10.0–21.8), respectively. There were no significant associations between levels of PAR, TMB, or MSI with outcomes. The DDR transcripts PARP3 and RBX1 significantly correlated with OS.

Interpretation

This is the first report of a PARPi-chemoradiotherapy combination in PC. The regimen was safe, tolerable at the RP2D, and clinically active as an upfront treatment strategy in patients biologically unselected by upfront chemotherapy. Expression of the DDR transcripts, PARP3 and RBX1, were associated with OS suggesting validation in a follow up phase 2 study.

Fund

Phase One Foundation; National Institutes of Health [1R01CA188480-01A1, P01 CA098912]. Veliparib was provided by Abbvie.

The role of pre-operative imaging and double balloon enteroscopy in the surgical management of small bowel neuroendocrine tumors: Is it necessary?

BACKGROUND AND OBJECTIVES

Pre-operative localization of small bowel neuroendocrine tumors (SBNET) is important for operative planning. The aim was to determine the effectiveness of pre-operative imaging and double-balloon enteroscopy (DBE) in identifying extent of disease.

METHODS

Database review identified 85 patients with primary SBNET between 2006 and 2013. Analysis included patients who underwent imaging, endoscopy, and surgery at our institution.

RESULTS

Average age was 60.7 years. Sixty-six (77.1%) patients had a primary NET in the ileum. Seventy-two patients (67.3%) underwent CT, 47 (46.7%) had MRI, 44 (46.7%) had somatostatin receptor imaging (SRI), and 41 (39.3%) underwent DBE. The sensitivity of each in identifying the NET was 59.7% for CT, 54% for MRI, 56% for SRI, and 88.1% for DBE. Eighteen (21.2%) patients had primary tumors not identified on imaging. Of these 18, 13 underwent DBE, and 12 of 13 (92.3%) DBEs identified the primary lesion. DBE was significantly better at identifying the primary NET than CT, MRI or SRI (P = 0.004, 0.007, and 0.012).

CONCLUSIONS

Most SBNETs are identified with a combination of imaging modalities. In those with unidentified primary tumors after imaging, DBE should be considered as it may provide valuable information as to the location of the primary tumor.

Imaging of Neuroendocrine Tumors: Indications, Interpretations, Limits, and Pitfalls

Imaging is critical in the diagnosis, prognosis, and management of neuroendocrine tumors (NETs). NETs share common imaging features, but each type exhibits unique features. Computed tomography scans or MRI of the abdomen is used to assess tumor burden routinely. Functional imaging with octreotide scan or gallium-68 somatostatin analog PET is used selectively to confirm diagnosis and guide therapy. Clinicians and radiologists should be familiar with the indications and interpretations of imaging modalities. Novel functional imaging modalities likely will be developed to detect small NETs, predict prognosis, guide therapeutic choices, and design novel therapies.

Fulminant clostridium difficile colitis: comparing computed tomography with histopathology: are they concordant?

A Total abdominal colectomy (TAC) is recommended for fulminant Clostridium difficile colitis (FCDC) because intraoperative assessment of diseased segments is inaccurate. To determine whether computerized tomography (CT) provides an accurate assessment of disease, we examined the concordance between CT and histopathologic colitis distribution in patients undergoing TAC for FCDC. The ileocolon was divided into seven distinct segments. Of 20 patients meeting criteria, the median interval between preoperative CT and TAC was 1.5 days (range, 0 to 23 days), and mortality was 65 per cent. The CT distribution of colitis was pancolitis in 12 patients and segmental in eight. Nine of the 12 patients with CT pancolitis had histologic pancolitis (75% concordance). Four of the eight patients with CT-diagnosed segmental disease had histologic segmental disease (50% concordance). For patients with FCDC, the distribution of colitis on CT agrees with the histopathologic extent of disease in the majority of patients. However, discordance between CT and histologic extent of disease was present in 25 to 50 per cent of patients. Therefore, the recommendation for TAC rather than segmental resection for FCDC remains justified.

Fulminant Clostridium difficile Colitis: Comparing Computed Tomography with Histopathology: Are They Concordant?

A Total abdominal colectomy (TAC) is recommended for fulminant Clostridium difficile colitis (FCDC) because intraoperative assessment of diseased segments is inaccurate. To determine whether computerized tomography (CT) provides an accurate assessment of disease, we examined the concordance between CT and histopathologic colitis distribution in patients undergoing TAC for FCDC. The ileocolon was divided into seven distinct segments. Of 20 patients meeting criteria, the median interval between preoperative CT and TAC was 1.5 days (range, 0 to 23 days), and mortality was 65 per cent. The CT distribution of colitis was pancolitis in 12 patients and segmental in eight. Nine of the 12 patients with CT pancolitis had histologic pancolitis (75% concordance). Four of the eight patients with CT-diagnosed segmental disease had histologic segmental disease (50% concordance). For patients with FCDC, the distribution of colitis on CT agrees with the histopathologic extent of disease in the majority of patients. However, discordance between CT and histologic extent of disease was present in 25 to 50 per cent of patients. Therefore, the recommendation for TAC rather than segmental resection for FCDC remains justified.

Recurrence of pancreatic ductal adenocarcinoma after pancreaticoduodenectomy: Is there a role for locoregional treatment?

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Background: The majority of patients undergoing potentially curative surgery for pancreatic ductal adenocarcinoma (PDA) will face recurrence. While other types of metastatic tumors are often treated with loco-regional therapy, this approach is rarely applied to metastatic PDA. We examined recurrence patterns of PDA and the potential application of loco-regional treatment. Methods: Evaluation of a prospective database of patients undergoing pancreaticoduodenctomy at an academic institution by a single surgeon. Patients: Pancreaticoduodenectomy for PDA was performed in 95 patients between 2002 and 2012. Margin status was R0 in 88 (93%) and R1 in the remainder. Results: Overall median survival was 27 months and 1 and 3 year survival was 68% and 41%. Known recurrence occurred in 44 of 64 patients (69%) at a median of 20.9 months, while the status of 31 patients was unknown. The most common site of initial recurrence was liver (n=19, median 9.2 months post-surgery), followed by local recurrence (n=15; median 18.7 months) and lung (n=5; median 5.2 months). Patients with R0 margin vs R1 recurred at a median 21 vs 5 months. In our series, 6 patients (5/6 treated in the last 2 years) underwent loco-regional treatment of recurrent disease, including liver resection (n=2), stereotactic radiotherapy (n=2), hepatic ablation (n=1) or radioembolization (n=1). All 6 patients treated with loco-regional therapy are alive at a median of 15.6 months after recurrence and a median of 25.3 months since initial surgery. Conclusions: The initial site of recurrent PDA after pancreaticoduodenectomy is usually liver, and the major risk factor for recurrence is the margin status at resection. Loco-regional modalities for the treatment of recurrent PDA hold promise in select patients. The tendency to utilize loco-regional therapy for recurrent PDA is increasing and warrants continued consideration.