Ahmed Larbi

MRI for response assessment in metastatic bone disease

AbstractBackgroundBeyond lesion detection and characterisation, and disease staging, the quantification of the tumour load and assessment of response to treatment are daily expectations in oncology.MethodsBone lesions have been considered “non-measurable” for years as opposed to lesions involving soft tissues and “solid” organs like the lungs or liver, for which response evaluation criteria are used in every day practice. This is due to the lack of sensitivity, specificity and measurement capabilities of imaging techniques available for bone assessment, i.e. skeletal scintigraphy (SS), radiographs and computed tomography (CT).ResultsThis paper reviews the possibilities and limitations of these techniques and highlights the possibilities of positron emission tomography (PET), but mainly concentrates on magnetic resonance imaging (MRI).ConclusionPractical morphological and quantitative approaches are proposed to evaluate the treatment response of bone marrow lesions using “anatomical” MRI. Recent developments of MRI, i.e. dynamic contrast-enhanced (DCE) imaging and diffusion-weighted imaging (DWI), are also covered.Key Points• MRI offers improved evaluation of skeletal metastases and their response to treatment. • This new indication for MRI has wide potential impact on radiological practice. • MRI helps meet the expectations of the oncological community. • We emphasise the practical aspects, with didactic cases and illustrations.

One-step TNM staging of high-risk prostate cancer using magnetic resonance imaging (MRI): Toward an upfront simplified "all-in-one" imaging approach?

Multiparametric magnetic resonance imaging (mpMRI) is the standard for local prostate cancer (PCa) staging. Whole‐body MRI (wbMRI) has shown capabilities for metastatic screening. This study assesses the feasibility and value of an all‐in‐one AJCC TNM staging of PCa during a unique MRI session combining mpMRI and wbMRI.

Dose reduction with iterative reconstruction: Optimization of CT protocols in clinical practice

OBJECTIVES To create an adaptable and global approach for optimizing MDCT protocols by evaluating the influence of acquisition parameters and Iterative Reconstruction (IR) on dose reduction and image quality. MATERIALS AND METHODS MDCT acquisitions were performed on quality image phantom by varying kVp, mAs, and pitch for the same collimation. The raw data were reconstructed by FBP and Sinogram Affirmed Iterative Reconstruction (SAFIRE) with different reconstruction kernel and thickness. A total of 4032 combinations of parameters were obtained. Indices of quality image (image noise, NCT, CNR, SNR, NPS and MTF) were analyzed. We developed a software in order to facilitate the optimization between dose reduction and image quality. Its outcomes were verified on an adult anthropomorphic phantom. RESULTS Dose reduction resulted in the increase of image noise and the decrease of SNR and CNR. The use of IR improved these indices for the same dose without affecting NCT and MTF. The image validation was performed by the anthropomorphic phantom. The software proposed combinations of parameters to reduce doses while keeping indices of the image quality adequate. We observed a CTDIvol reduction between -44% and -83% as compared to the French diagnostic reference levels (DRL) for different anatomical localization. CONCLUSION The software developed in this study may help radiologists in selecting adequate combinations of parameters that allows to obtain an appropriate image with dose reduction.

Whole-Body 3D T1-weighted MR Imaging in Patients with Prostate Cancer: Feasibility and Evaluation in Screening for Metastatic Disease

PURPOSE To develop and assess the diagnostic performance of a three-dimensional (3D) whole-body T1-weighted magnetic resonance (MR) imaging pulse sequence at 3.0 T for bone and node staging in patients with prostate cancer. MATERIALS AND METHODS This prospective study was approved by the institutional ethics committee; informed consent was obtained from all patients. Thirty patients with prostate cancer at high risk for metastases underwent whole-body 3D T1-weighted imaging in addition to the routine MR imaging protocol for node and/or bone metastasis screening, which included coronal two-dimensional (2D) whole-body T1-weighted MR imaging, sagittal proton-density fat-saturated (PDFS) imaging of the spine, and whole-body diffusion-weighted MR imaging. Two observers read the 2D and 3D images separately in a blinded manner for bone and node screening. Images were read in random order. The consensus review of MR images and the findings at prospective clinical and MR imaging follow-up at 6 months were used as the standard of reference. The interobserver agreement and diagnostic performance of each sequence were assessed on per-patient and per-lesion bases. RESULTS The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were significantly higher with whole-body 3D T1-weighted imaging than with whole-body 2D T1-weighted imaging regardless of the reference region (bone or fat) and lesion location (bone or node) (P < .003 for all). For node metastasis, diagnostic performance (area under the receiver operating characteristic curve) was higher for whole-body 3D T1-weighted imaging (per-patient analysis; observer 1: P < .001 for 2D T1-weighted imaging vs 3D T1-weighted imaging, P = .006 for 2D T1-weighted imaging + PDFS imaging vs 3D T1-weighted imaging; observer 2: P = .006 for 2D T1-weighted imaging vs 3D T1-weighted imaging, P = .006 for 2D T1-weighted imaging + PDFS imaging vs 3D T1-weighted imaging), as was sensitivity (per-lesion analysis; observer 1: P < .001 for 2D T1-weighted imaging vs 3D T1-weighted imaging, P < .001 for 2D T1-weighted imaging + PDFS imaging vs 3D T1-weighted imaging; observer 2: P < .001 for 2D T1-weighted imaging vs 3D T1-weighted imaging, P < .001 for 2D T1-weighted imaging + PDFS imaging vs 3D T1-weighted imaging). CONCLUSION Whole-body MR imaging is feasible with a 3D T1-weighted sequence and provides better SNR and CNR compared with 2D sequences, with a diagnostic performance that is as good or better for the detection of bone metastases and better for the detection of lymph node metastases.

Bilateral ischiofemoral impingement in a patient with hereditary multiple exostoses.

The skeletal anatomy of the hip provides two main locations for impingement: abnormal contact between the acetabulum and femur (femoroacetabular impingement) or between the ischium and femur (ischiofemoral impingement). We report a case of bilateral ischiofemoral impingement in a patient with hereditary multiple exostoses. The association of exostoses and femoral metaphyseal widening resulted in the narrowing of the ischiofemoral spaces. Pain was improved on the left side by resection of the ischial exostosis.

Drug-induced tendinopathy: from physiology to clinical applications.

Drug-induced tendon toxicity is rare but often underestimated. To date, four main drug classes have been incriminated in tendinopathies. Quinolones and long-term glucocorticoids are the most widely known, but statins and aromatase inhibitors can also induce tendon damage. The specific pathophysiological mechanisms responsible for drug-induced tendinopathies remain unknown. Proven risk factors have been identified, such as age older than 60 years, pre-existing tendinopathy, and potentiation of toxic effects when several drug classes are used in combination. Mean time to symptom onset varies from a few days with quinolones to several months with statins and several years for long-term glucocorticoid therapy. The most common sites of involvement are the lower limb tendons, most notably the body of the Achilles tendon. The first part of this review discusses tendon anatomy and the pathophysiology and radiological manifestations of tendinopathies. The second part provides details on the main characteristics of each of the drugs classes associated with tendon toxicity.

Efficacy of intra-tendinous injection of platelet-rich plasma in treating tendinosis: comprehensive assessment of a rat model

ObjectivesTo assess the potential of intra-tendinous injection of platelet rich plasma (PRP) to treat tendinosis (T+) in a rat model of patellar and Achilles T+, and evaluate its local toxicity.MethodsThirty rats (120 patellar and Achilles tendons) were used. We induced T+ into 80 tendons (patellar = 40, Achilles = 40) by injecting collagenase at day 0 under ultrasound (US) guidance. Clinical examination and US at day 3, followed by US-guided intra-tendinous injection of either PRP (PRPT+, n = 40) or physiological serum (ST+, n = 40, control). Follow-up was at days 6, 13, 18 and 25 using clinical, US and histological evaluation. To study PRP toxicity, we injected PRP into 40 normal tendons (PRPT-) and compared with 40 untreated normal tendons (T-).ResultsAll PRPT+ showed better joint mobilisation compared with ST+ at day 6 (P = 0.005), day 13 (P = 0.02), day 18 (P = 0.003) and day 25 (P = 0.01). Similar results were found regarding US and histology, with smaller collagen fibre diameters (day 6, P = 0.003, day 25, P ≤ 0.004), less disorganisation and fewer neovessels (day 6, P = 0.003, day 25, P = 0.0003) in PRPT+ compared with ST+. Comparison between PRPT- and T- showed no PRP toxicity (P = 0.18).ConclusionsOur study suggests that mono-injection of PRP in T+ improves tendon healing, with no local toxicity.Key Points• We assessed the potential of platelet rich plasma (PRP) to treat tendinosis.• We treated patellar and Achilles tendinosis in a rat model.• We evaluated clinical, imaging and histological data.• Intra-tendinous PRP injection could be useful in the treatment of tendinosis.

Whole body MRI (WB‐MRI) assessment of metastatic spread in prostate cancer: Therapeutic perspectives on targeted management of oligometastatic disease

To determine the proportion of prostate cancer (PCa) patients with oligometastatic disease (≤3 synchronous lesions) using whole body magnetic resonance imaging with diffusion‐weighted imaging (WB‐MRI/DWI). To determine the proportion of patients with nodal disease confined within currently accepted target areas for extended lymph node dissection (eLND) and pelvic external beam radiation therapy (EBRT).

Novel imaging techniques reshape the landscape in high-risk prostate cancers.

Purpose of review High-risk prostate cancers (PCa), that is, those with prostate-specific antigen greater than 20 ng/dl, Gleason Score of at least 8, or extraprostatic spread, are nowadays commonly treated by surgery and radiotherapy combined with a fixed period of systemic treatment. Implementing these strategies requires an exhaustive assessment of metastatic spread. This review addresses the latest development in integrated imaging techniques. Recent findings In contrast to the progress that has been made in PCa treatment, diagnostic strategies have not much evolved. Most guidelines still recognize 99mTc bone scintigraphy and computed tomography (CT) as cornerstone modalities to assess metastatic spread in bones and lymph nodes. Therefore, modern imaging techniques should primarily focus on these two targets. PET with various tracers, including 11C or 18F-choline and 18F-sodium fluoride, and MRI with or without diffusion-weighted imaging are competing to supplant bone scan and CT scan as reference imaging techniques. This review focuses on the latest development of these techniques and analyses their potential impact in everyday urology practice. Summary Although certain hurdles remain, PET and whole-body MRI have the ability to supplant 99mTc bone scan and CT as upfront test to assess metastatic spread in high-risk PCa.

Diffusion-weighted MR imaging in musculoskeletal diseases: current concepts

MR imaging is currently regarded as a pivotal technique for the assessment of a variety of musculoskeletal conditions. Diffusion-weighted MR imaging (DWI) is a relatively recent sequence that provides information on the degree of cellularity of lesions. Apparent diffusion coefficient (ADC) value provides information on the movement of water molecules outside the cells. The literature contains many studies that have evaluated the role of DWI in musculoskeletal diseases. However, to date they yielded conflicting results on the use and the diagnostic capabilities of DWI in the area of musculoskeletal diseases. However, many of them have showed that DWI is a useful technique for the evaluation of the extent of the disease in a subset of musculoskeletal cancers. In terms of tissue characterization, DWI may be an adjunct to the more conventional MR imaging techniques but should be interpreted along with the signal of the lesion as observed on conventional sequences, especially in musculoskeletal cancers. Regarding the monitoring of response to therapy in cancer or inflammatory disease, the use of ADC value may represent a more reliable additional tool but must be compared to the initial ADC value of the lesions along with the knowledge of the actual therapy.