Medical imaging

Quantitative evaluation of the reduction of distortion and metallic artifacts in magnetic resonance images using the multiacquisition variable‑resonance image combination selective sequence

Magnetic resonance imaging (MRI) is superior to computed tomography (CT) in determining changes in tissue structure, such as those observed following inflammation and infection. However, when metal implants or other metal objects are present, MRI exhibits more distortion and artifacts compared with CT, which hinders the accurate measurement of the implants. A limited number of reports have examined whether the novel MRI sequence, multiacquisition variable-resonance image combination selective (MAVRIC SL), can accurately measure metal implants without distortion. Therefore, the present study aimed to demonstrate whether MAVRIC SL could accurately measure metal implants without distortion and whether the area around the metal implants could be well delineated without artifacts. An agar phantom containing a titanium alloy lumbar implant was used for the present study and was imaged using a 3.0 T MRI machine. A total of three imaging sequences, namely MAVRIC SL, CUBE and magnetic image compilation (MAGiC), were applied and the results were compared. Distortion was evaluated by measuring the screw diameter and distance between the screws multiple times in the phase and frequency directions by two different investigators. The artifact region around the implant was examined using a quantitative method following standardization of the phantom signal values. It was revealed that MAVRIC SL was a superior sequence compared with CUBE and MAGiC, as there was significantly less distortion, a lack of bias between the two different investigators and significantly reduced artifact regions. These results suggested the possibility of utilizing MAVRIC SL for follow-up to observe metal implant insertions.

Safety Analysis of Iobitridol as a Nonionic Contrast Medium: A Postmarketing Multicenter Surveillance Study With 94,960 Patients Almost 20 Years After Introduction

OBJECTIVES

Our study sought to reevaluate the safety and diagnostic efficacy of iobitridol as a nonionic contrast medium after almost 20 years of use.

MATERIALS AND METHODS

This noninterventional postmarketing surveillance noncontrolled, multicenter (168 centers in Germany) study enrolled 94,960 patients receiving intravenous or intra-arterial iobitridol. The majority of the adjusted population (n = 92,550, 98.2%) underwent either computed tomography examination (n = 46,502, 49.3%) or intravenous urography (n = 46,048, 48.8%). A standardized questionnaire was used to ascertain patient's information, known risk factors, renal function status, premedication, type of examination, injection of contrast agent, imaging quality, diagnostic value, and safety.

RESULTS

A total of 469 patients (0.49%) experienced an adverse event (AE), and 24 patients (0.025%) reported a serious AE (SAE). All patients recovered and no fatal event occurred. The prevalence of AE was significantly higher in patients with at least one risk factor, with premedication, with a history of AE, in female and patients younger than 60 years old (P < 0.05). Presence of at least one risk factor is the only predictive factor for the prevalence of SAE (P = 0.042). In patients with a history of AE, premedication did not significantly lower the AE rate (P = 0.737). No statistically significant difference in the prevalence of AE between the different combination of cortisone and/or antihistamines as pretreatment was found.

CONCLUSIONS

Iobitridol is a safe contrast medium with a high tolerability and efficacy. Presence of risk factors such as cardiovascular diseases, allergies, or asthma was the only significant predictive factor for an AE and an SAE. Premedication did not significantly lower the occurrence of an AE and an SAE.

Assessment of cam morphology of the hip with ultra sound imaging by physical therapists is reliable and valid

BACKGROUND

Femoroacetabular impingement syndrome is considered present when a combination of clinical symptoms, signs and morphological features of the hip co-exist. Imaging is increasingly popular in primary health care settings with physical therapists performing ultrasound (US).

OBJECTIVE

The aim of this study was to assess the diagnostic accuracy and inter-rater reliability of ultrasound in determining presence of cam morphology.

DESIGN

A concurrent validity and inter-rater reliability study.

METHODS

The presence of cam morphology of the hip was determined by α angle measures using Kinovea software. A cam was defined present when the α angle >60°. The index test was US and radiographs served as a gold standard.

RESULTS

Correlation between the radiographic α angle and ultrasound measures was r = 0.82 (p < 0.01). Inter-rater reliability was high with an ICC of 0.74 (95% CI 0.61-0.84). The predictive value for presence of cam morphology had a sensitivity of 79% and a specificity of 94%. The positive predictive value was 79% whereas the negative predictive value was 94%. Total accuracy was 90%.

CONCLUSIONS

Ultrasound conducted by trained physical therapists is a valid, reliable, specific and sensitive diagnostic tool to assess the presence of cam morphology.

The use of ionising radiation in trauma and orthopaedic theatres

Ionising radiation is used extensively in trauma and orthopaedic perioperative practice for operative planning and intraoperative decision making. Radiation poses risks to patients and theatre staff, and it is important to always justify, optimise and limit the exposure. This is facilitated by a thorough understanding and awareness of radiation, as well as a sound knowledge of the precautions required for using this technology to minimise the risks of radiation.

Mandibular invasion by squamous cell carcinoma: a computed tomographic and histological study

Our knowledge of the entry and spread of oral cell carcinoma (SCC) into the mandible is increasing, making an impact on surgical planning. Fourteen resection specimens of mandibular bone and adjacent SCC were radiographically (CT) and histologically investigated. In six cases there was no involvement of mandibular bone; a continuous periosteal layer separated the tumour from bone. The remaining eight specimens showed bony involvement with good correlation between corresponding CT and histological slices in the five edentate cases. The site of entry of the tumour into the bone was usually through the alveolar crest with additional spread through the lingual cortex in tumours that lay lingual to the mandible. Although limited, our data shows that the main site of entry of SCC is through the alveolar crest. It also highlights the usefulness of CT in the identification of bone involvement in edentate cases. This information may assist in the planning of operations to preserve as much bone as is consistent with complete excision of the tumour.

Contrast agents

Pharmacologic development and clinical use of nonionic low osmolality contrast agents have lowered incidences of contrast reactions. Exclusive use of these agents may be limited owing to their high costs. Ionic high osmolality agents still provide reliable means of positive contrast enhancement, and minimal problems with reactions have been experienced in veterinary patients.