Direct MR arthrography without image guidance: a practical guide, joint-by-joint.

Direct MR arthrography (dMRA) is a fundamental technique in diagnosing pathology in major peripheral joints, allowing for precise evaluation of intra-articular structures. Although injection guidance is typically performed using imaging techniques such as ultrasound or fluoroscopy, puncture via anatomical landmarks may be useful in certain circumstances where it has been proven to be a safe and effective procedure. This paper describes the indications and injection technique of dMRA, joint by joint, focusing on the different technical details, from the most common locations, like the shoulder or hip, to those with more restricted clinical indications, such as the wrist, knee, elbow, or ankle. The most relevant anatomical landmarks are detailed for each joint, aiding in the intra-articular introduction of diluted contrast, highlighting the most accessible trajectories and structures to avoid when inserting the needle. Additionally, tips are provided to facilitate proper joint distension. With all this information, this paper aims to serve as a suitable reference guide for performing dMRA without image guidance if needed.

Quantitative myocardial perfusion with stress dual-energy CT: iodine concentration differences between normal and ischemic or necrotic myocardium. Initial experience.

OBJECTIVES: To determine whether the quantification of iodine with stress dual-energy computed tomography (DECT-S) allows for the discrimination between a normal and an ischemic or necrotic myocardium using magnetic resonance (MR) as a reference. METHODS: This retrospective study was approved by the institutional review board, with waiver of informed consent. Thirty-six cardiac MR and DECT-S images from patients with suspected coronary artery disease were evaluated. Perfusion defects were visually determined, and myocardial iodine concentration was calculated by two observers using DECT colour-coded iodine maps. Iodine concentration differences were calculated using parametric tests. Receiver operating characteristic (ROC) curve analysis was conducted to estimate the optimal iodine concentration threshold for discriminating pathologic myocardium. RESULTS: In total, 576 cardiac segments were evaluated. There were differences in mean iodine concentration (p < 0.001) between normal (2.56 ± 0.66 mg/mL), ischemic (1.98 ± 0.36 mg/dL) and infarcted segments (1.35 ± 0.57 mg/mL). A myocardium iodine concentration of 2.1 mg/mL represented the optimal threshold to discriminate between normal and pathologic myocardium (sensitivity 75 %, specificity 73.6 %, area under the curve 0.806). Excellent agreement was found in measured myocardium iodine concentration (intraclass correlation coefficient 0.814). CONCLUSION: Cardiac DECT-S with iodine quantification may be useful to differentiate healthy and ischemic or necrotic myocardium. KEY POINTS: • DECT-S allows for determination of myocardial iodine concentration as a quantitative perfusion parameter. • A high interobserver correlation exists in measuring myocardial iodine concentration with DECT-S. • Myocardial iodine concentration may be useful in the assessment of patients with CAD.

Benign soft-tissue lesions of the fingers: radiopathological correlation and clinical considerations.

Soft-tissue lesions of the fingers are commonly found in daily clinical practice. A wide range of tumors and pseudotumors have been described in this location, and the majority of them are benign. Ganglion cysts are the most common entity, and the localized type of tenosynovial giant cell tumors are the most frequent solid condition. Both may be easily recognized owing to their typical clinical and radiological characteristics. However, categorization of the spectrum of soft-tissue lesions of the fingers remains limited, despite imaging development, and many patients undergo surgery before radiological or histological diagnosis. Clinical history, radiographic features, and ultrasound and magnetic resonance patterns may help in obtaining the correct diagnosis or reducing the list of differential diagnoses. Radiologists should be familiar with imaging findings so that they can determine the size, extension, and affected neighboring anatomical structures, and provide information that allows adequate presurgical counseling.

Evaluation of response to conventional chemotherapy and radiotherapy by perfusion computed tomography in non-small cell lung cancer (NSCLC).

BACKGROUND: To evaluate changes in perfusion computed tomography (PCT) parameters induced by treatment with conventional chemotherapy (CCT) alone or with CCT and radiation therapy (RT) in patients with non-small cell lung cancer (NSCLC) and to determine whether these changes correlate with response as defined by the response evaluation criteria in solid tumours version 1.1 (RECIST-1.1). METHODS: Fifty-three patients with a histological diagnosis of NSCLC prospectively underwent PCT of the whole tumour, before/after CCT or before/after CCT and RT. Blood flow (BF), blood volume (BV), permeability (PMB), and mean transit time (MTT) were compared before and after treatment and with the response as defined by RECIST-1.1. The relationship between changes in the perfusion parameters and in tumour size was also evaluated. RESULTS: PCT parameters decreased after treatment, significantly for BV (p = 0.002) and MTT (p = 0.027). The 30 patients with partial response had a significant decrease of 21% for BV (p = 0.006) and 17% for MTT (p = 0.031). A non-significant decrease in all perfusion parameters was found in patients with stable disease (p > 0.137). In patients with progressive disease, MTT decreased by 10% (p = 0.465) and the other parameters did not significantly vary (p > 0.809). No significant correlation was found between changes in size and PCT parameters (p > 0.145). CONCLUSIONS: Treatment of NSCLC with platinum derivatives, with or without RT, induces changes in PCT parameters. Partial response is associated with a significant decrease in BV and MTT, attributable to the effect of the treatment on tumour vascularisation.

Characteristics of computed tomography perfusion parameters in non-small-cell-lung-cancer and its relationship to histology, size, stage an treatment response.

OBJECTIVES: To analyze computed tomography perfusion (CTP) parameters in NSCLC. MATERIALS AND METHODS: Prospective study, 152 patients with NSCLC. CTP parameters were correlated with histology, stage, size and response to conventional chemotherapy/radiotherapy. RESULTS: Neuroendocrine tumours presented higher BV (p 0.002). Negative correlation of PMB (p 0.003) and positive of MTT (p 0.046) with T stage was found. BF showed negative correlation with size. No differences were found with the RECIST levels of response to chemotherapy/radiotherapy. CONCLUSIONS: CTP parameters were highly variable. Neuroendocrine tumours presented higher BV and PMB values. Perfusion parameters do not differ depending on the stage and do not predict response to treatment.