Magnetic Resonance Imaging Log Research Articles

MRI log file analysis for workflow improvement

Magnetic Resonance Imaging (MRI) is an important diagnostic scanning tool for the detection and monitoring of specific diseases and conditions. However, the equipment cost, maintenance and specialty training of the technologists make the examination expensive. Consequently, unnecessary scanner time caused by poor scheduling, repeated sequences, aborted sequences, scanner idleness, or capture of non-diagnostic or low-value sequences is an opportunity to reduce costs and increase efficiency. This paper analyzes data collected from log files on 29 scanners over several years. ‘Wasted’ time is defined and key performance indicators (KPIs) are identified. A decrease in exam duration results when actively modifying and monitoring the number of sequences that comprise the exam card for a protocol.

FDG PET-CT as an important diagnostic tool and prognostic marker in suspected recurrent cervical carcinoma after radiotherapy: comparison with MRI.

Recurrent disease in post-irradiation patients with cervical cancer is often difficult to delineate on magnetic resonance imaging (MRI), because posttreatment changes can have a similar appearance, and further evaluation is often required. The aims of the study were to evaluate positron emission tomography/computed tomography with 18F-fluorodeoxyglucose (FDG PET-CT) diagnostic role in suspected recurrent cervical cancer after radiotherapy, compare it to MRI, and assess their prognostic impact in these patients. This cohort retrospective study included patients previously treated with radiotherapy for carcinoma of uterine cervix with suspected recurrence, who had undergone MRI of abdomen and pelvis, and were subsequently evaluated on FDG PET-CT, with minimum follow-up period of 12 months. In the total of 84 patients included in analysis, MRI vs. FDG PET-CT showed sensitivity, specificity and accuracy of 80.1%, 52.4% and 66.7%, vs. 97.6%, 61.9% and 79.8%, respectively. Patients with positive findings on MRI (Log Rank, p = 0.003) and PET-CT (Log Rank, p < 0.001) had shorter progression-free survival (PFS) than those with negative results. In univariate Cox regression models, MRI and FDG PET-CT results were found to be related to PFS (p = 0.005 and p < 0.001, respectively). However, multivariate analysis proved only FDG PET-CT to be independent prognostic factor, where patients with positive FDG PET-CT results had almost nine times higher risk of progression (p < 0.001). FDG PET-CT represents useful diagnostic tool in suspected recurrent cervical cancer after radiotherapy, showing high sensitivity in its detection. In addition, it is an independent factor in predicting progression-free survival in these patients.

Automated Billing Code Retrieval from MRI Scanner Log Data

Although the level of digitalization and automation steadily increases in radiology, billing coding for magnetic resonance imaging (MRI) exams in the radiology department is still based on manual input from the technologist. After the exam completion, the technologist enters the corresponding exam codes that are associated with billing codes in the radiology information system. Moreover, additional billing codes are added or removed, depending on the performed procedure. This workflow is time-consuming and we showed that billing codes reported by the technologists contain errors. The coding workflow can benefit from an automated system, and thus a prediction model for automated assignment of billing codes for MRI exams based on MRI log data is developed in this work. To the best of our knowledge, it is the first attempt to focus on the prediction of billing codes from modality log data. MRI log data provide a variety of information, including the set of executed MR sequences, MR scanner table movements, and given a contrast medium. MR sequence names are standardized using a heuristic approach and incorporated into the features for the prediction. The prediction model is trained on 9754 MRI exams and tested on 1 month of log data (423 MRI exams) from two MRI scanners of the radiology site for the Swiss medical tariffication system Tarmed. The developed model, an ensemble of classifier chains with multilayer perceptron as a base classifier, predicts medical billing codes for MRI exams with a micro-averaged F1-score of 97.8% (recall 98.1%, precision 97.5%). Manual coding reaches a micro-averaged F1-score of 98.1% (recall 97.4%, precision 98.8%). Thus, the performance of automated coding is close to human performance. Integrated into the clinical environment, this work has the potential to free the technologist from a non-value adding an administrative task, therefore enhance the MRI workflow, and prevent coding errors.

OP27.07: Does imaging correlate with clinical findings for morbidly adherent placenta? An audit from University Hospitals Coventry and Warwickshire

The incidence of morbidly adherent placenta is rising secondary to the increasing Caesarean rate and advancing maternal age. The Royal College of Obstetricians and Gynecologists (RCOG) recommends that women with an anterior low placenta and a Caesarean section scar at 32 completed weeks gestation undergo further imaging with either ultrasonography and/or magnetic resonance imaging (MRI) to distinguish if there is likely placenta accreta. The aim of this audit was to determine if imaging correlated with clinical findings in our unit. Patients were identified from the fetal medicine department and MRI log from January 2015 until March 2017. Images, reports and clinical notes were reviewed to determine if morbidly adherent placenta was suspected on imaging and found at the time of Caesarean section. Six patients were identified. The number of previous Caesarean sections ranged from 1 to 5. 5 patients underwent colour Doppler ultrasonography all of which were suspicious for placenta accreta. 6 patients underwent MRI of which 5 were suspicious for at least accreta. For the patient with an MRI showing previa only, clinical findings correlated with this scan. One patient is awaiting surgery. For the other four patients there were three placental accreta and one percreta. Blood loss ranged from 1.4 - 10.5 litres. Two patients had a hysterectomy. From this study the fetal medicine Colour Doppler ultrasonography sensitivity was 100%, with a 100% positive predicative value. For MRI there was 100% sensitivity, specificity and positive and negative predictive values. Morbidly adherent placenta is uncommon but is increasing in incidence. RCOG states that colour Doppler has a sensitivity of 92% in detecting invasive placental disorders, which is similar to the sensitivity in our department. MRI has been shown to have a sensitivity of 93% and specificity of 71%. The sensitivity from this cohort was higher, which we have attributed to small sample size.

The Magnetic-Resonance While-Drilling Tool: Theory and Operation

Summary The first Magnetic-Resonance-Image Logging-While-Drilling (MRI-LWD*) tools have been built and field tested. The hardware was designed to provide data that are compatible with the Magnetic Resonance Imaging Log (MRIL®) wireline tool in terms of processing and interpretation. This paper discusses the theory of robust MRIL measurements in the drilling environment and reviews the theory of 7 relaxation time measurements. We report on the results of a field test in the Gulf of Mexico. The MRI-LWD device logged the entire total depth (TD) run from casing to TD and provided additional hydrocarbon-typing data in wiping mode over the target zones. Wireline MRIL data and conventional logs were used to verify the MRI-LWD measurements.

Use of intelligent systems in reservoir characterization via synthetic magnetic resonance logs

Magnetic Resonance Imaging (MRI) logs are well logs that use nuclear magnetic resonance to accurately measure free fluid, irreducible water (MBVI), and effective porosity (MPHI). Permeability is then calculated using a mathematical function that incorporates these measured properties. This paper describes the methodology developed to generate synthetic MRI logs using data obtained by conventional well logs such as SP, Gamma Ray, Caliper, and Resistivity. The synthetically generated logs are named Virtual Magnetic Imaging Logs or “VMRI” logs for short.

Irreducible Water Saturation From Magnetic-Resonance-Imaging Logs

This article is a synopsis of paper SPE 37772, "Determination of Irreducible Water Saturation by Use of Magnetic-Resonance-Imaging Logs (MRIL): A Case Study From East Texas, U.S.A.," by M.E. Oraby, SPE, and D.L. Eubanks, Halliburton Energy Services, originally presented at the 1997 SPE Middle East Oil Show, Manama, Bahrain, 15-18 March.

Utilizing Magnetic Resonance Imaging Logs, Openhole Logs, and Sidewall Core Analyses to Evaluate Shaly Sands for Water-Free Production: ABSTRACT

Nuclear magnetic resonance (NMR) logging using the new C Series Magnetic Resonance Imaging Log (MRIL) system is rapidly enhancing formation evaluation throughout the industry. By measuring irreducible water saturations, permeabilities, and effective porosities, MRIL data can help petrophysicists evaluate low-resistivity pays. In these environments, conventional openhole logs may not define all of the pay intervals. The MRIL system can also reduce the number of unnecessary completions in zones of potentially high water cut. MRIL tool theory and log presentations used with conventional logs and sidewall cores are presented along with field examples. Scanning electron microscope (SEM) analysis shows good correlation of varying grain size in sandstones with the T2 distribution and bulk volume irreducible water determined from the MRIL measurements. Analysis of each new well drilled in the study area shows how water-free production zones were defined. Because the MRIL data were not recorded on one of the wells, predictions from the conventional logs and the MRIL data collected on the other two wells were used to estimate productive zones in the first well. Discussion of additional formation characteristics, completion procedures, actual production, and predicted producibility of the shaly sands is presented. Integrated methodologies resulted in the perforation of 3more » new wells for a gross initial potential of 690 BOPD and 0 BWPD.« less

New logging tool identifies permeability in shaley sands

A logging tool overcame questionable results obtained by routine core analysis and other conventional techniques for identifying permeable zones. For this test, Lomax Exploration Co., in conjunction with the US Department of Energy (DOE), used Numar corp.'s magnetic resonance imaging log (MRIL) in the Monument Butte field, Duchesne County, Utah. The tool also enhanced the interpretation of conventional logs over the two zones of interest. Because of interbedded sands, shales, and silts, cores collected just inches apart can yield very different permeability and porosity values. As a result, sidewall core analysis has historically been misleading. Lomax Exploration felt that MRIL could improve permeability determinations for secondary recovery projects as well as aid in evaluating zones for initial production in the Uinta basin. The paper describes the Uinta basin, MRIL, MRIL logs, and well completion.

Applying NMR Spin-Echo Logging to Shaly Sand Formation Evaluation: Case Studies of Rocky Mountain Region Gas Wells: ABSTRACT

Conventional wireline logs often fail to provide a reliable evaluation of reservoir quality and producibility in shaly mud formations, particularly in the shaly gas sand reservoirs of the Rocky Mountains which are characterized by low porosity (i.e., <15 pu), low permeability (0.1 to 1 md), very fine grain size, and high irreducible water saturations. A new-generation nuclear magnetic resonance (NMR) logging tool, the Magnetic Resonance Imaging Log (MRIL{reg_sign}), enhances log interpretation in such situations by providing lithology-insensitive measurements of effective porosity and the volume fractions of free (i.e., mobile) and capillary-bound (immobile) fluid volumes. This paper presents three examples from Rocky Mountain region wells in which MRIL data were crucial for resolving ambiguous or otherwise misleading interpretations from conventional nuclear porosity and resistivity log data alone. In two wells in the Frontier Group, WY, conventional log responses are nearly identical - the nuclear logs show gas effect while deep resistivity is nearly constant at {approximately}10 ohmm and shows little contrast with readings in nearby shales - but only one well produces gas at commercial rates. In the producing well, the MRIL shows the Frontier internal has significant (6 to 8 pu) free-fluid volume while in the other well FFI averagesmore » {approximately}1 pu, consistent with production. In addition, permeabilities computed from MRIL porosity and free/bound fluid volume ratio show excellent agreement with core data and reveal that the permeability-thickness of this thick, low resistivity zone is comparable to that of an overlying thin, but prolific, gas-producing sand.« less

Utilizing Magnetic Resonance Imaging Logs, Open Hole Logs and Sidewall Core Analyses to Evaluate Shaly Sands for Water-Free Production: ABSTRACT

Utilizing Magnetic Resonance Imaging Logs, Open Hole Logs and Sidewall Core Analyses to Evaluate Shaly Sands for Water-Free Production: ABSTRACT