Ability of navigated 3D ultrasound to delineate gliomas and metastases--comparison of image interpretations with histopathology

BACKGROUND: The objective of the study was to test the ability of a 3D ultrasound (US) based intraoperative imaging and navigation system to delineate gliomas and metastases in a clinical setting. The 3D US data is displayed as reformatted 2D image slices. The quality of the displayed 3D data is affected both by the resolution of the acquired data and the reformatting process. In order to investigate whether or not 3D US could be used for reliable guidance in tumour surgery, a study was initiated to compare interpretations of imaged biopsy sites with histopathology. The system also enabled concomitant comparison of navigated preoperative MR with histopathology. METHOD: Eighty-five biopsies were sampled between 2-7 mm from the tumour border visible in the ultrasound images. Biopsies were collected from 28 operations (7 low-grade astrocytomas, 8 anaplastic astrocytomas, 7 glioblastomas and 6 metastases). Corresponding cross-sections of preoperative MR T1, MR T2 and intraoperative US were concomitantly displayed, steered by the biopsy forceps equipped with a positioning sensor. The surgeons' interpretation of the images at the electronically indicated biopsy sites were compared with the histopathology of the samples. FINDINGS: The ultrasound findings were in agreement with histopathology in 74% (n = 31) for low-grade astrocytomas, 83% (n = 18) for anaplastic astrocytomas, 77% (n = 26) for glioblastomas and 100% (n = 10) for metastases. Excluding irradiated patients, the results for glioblastomas improved to 80% concurrence (n = 20). As expected tumour cells were found in biopsies outside the US visible tumour border, especially in low-grade gliomas. Navigated 3D US have a significantly better agreement with histopathology than navigated MR T1 for low-grade astrocytomas. CONCLUSION: Reformatted images from 3D US volumes give a good delineation of metastases and the solid part of gliomas before starting the resection. Navigated 3D US is at least as reliable as navigated 3D MR to delineate gliomas and metastases.     

Progress in Two-Dimensional and Three-Dimensional Ultrasonic Tissue-Type Imaging of the Prostate Based on Spectrum Analysis and Nonlinear Classifiers

Spectrum analysis of radiofrequency (RF) ultrasonic echo signals often can sense tissue differences that are not visible on conventional ultrasonic images. Spectrum-analysis parameter values combined with other variables, such as serum prostate specific antigen (PSA) concentration, can be classified by neural networks to distinguish effectively between cancerous and noncancerous prostate tissues. Images based on neural network classification of spectral parameters and clinical variables can be advantageous for biopsy guidance, staging, and treatment planning and monitoring. A study based on 644 biopsies from 137 patients showed that these methods are significantly superior to B-mode image interpretation for differentiating cancerous from noncancerous prostate tissues. Using the histologic determination of tissue types as the gold standard, the area under the receiver-operator characteristic (ROC) curve for neural network classification based on spectrum analysis and PSA value for the 644 biopsies was 0.87 +/- 0.04, and the ROC curve are for a level-of-suspicion (LOS) assignment based on B-mode imaging was 0.64 +/- 0.04. Color-encoded and gray-scale images derived from neural network assignment of suspicion for cancer at each pixel location showed remarkable detail and suggested potential clinical value for biopsy guidance using real-time two-dimensional (2D) images and staging, treatment planning, and monitoring using three-dimensional (3D) images.     

Ability of navigated 3D ultrasound to delineate gliomas and metastases – comparison of image interpretations with histopathology

Summary Background. The objective of the study was to test the ability of a 3D ultrasound (US) based intraoperative imaging and navigation system to delineate gliomas and metastases in a clinical setting. The 3D US data is displayed as reformatted 2D image slices. The quality of the displayed 3D data is affected both by the resolution of the acquired data and the reformatting process. In order to investigate whether or not 3D US could be used for reliable guidance in tumour surgery, a study was initiated to compare interpretations of imaged biopsy sites with histopathology. The system also enabled concomitant comparison of navigated preoperative MR with histopathology. Method. Eighty-five biopsies were sampled between 2–7 mm from the tumour border visible in the ultrasound images. Biopsies were collected from 28 operations (7 low-grade astrocytomas, 8 anaplastic astrocytomas, 7 glioblastomas and 6 metastases). Corresponding cross-sections of preoperative MR T1, MR T2 and intraoperative US were concomitantly displayed, steered by the biopsy forceps equipped with a positioning sensor. The surgeons’ interpretation of the images at the electronically indicated biopsy sites were compared with the histopathology of the samples. Findings. The ultrasound findings were in agreement with histopathology in 74% (n = 31) for low-grade astrocytomas, 83% (n = 18) for anaplastic astrocytomas, 77% (n = 26) for glioblastomas and 100% (n = 10) for metastases. Excluding irradiated patients, the results for glioblastomas improved to 80% concurrence (n = 20). As expected tumour cells were found in biopsies outside the US visible tumour border, especially in low-grade gliomas. Navigated 3D US have a significantly better agreement with histopathology than navigated MR T1 for low-grade astrocytomas. Conclusion. Reformatted images from 3D US volumes give a good delineation of metastases and the solid part of gliomas before starting the resection. Navigated 3D US is at least as reliable as navigated 3D MR to delineate gliomas and metastases.     

Ultrasonographic evaluation of the Bankart lesion

The Bankart lesion is an essential finding of traumatic anterior shoulder instability. The purpose of this study was to clarify the reliability of diagnosis by ultrasonography (US) of the Bankart lesion when using an axillary approach. Six cadaveric shoulders were examined by US from the axilla. The shoulders were then dissected along the plane of the ultrasonic beam. The labrum at the 4-o'clock position of all 6 cadavers was present along the ultrasonic plane; there were no obstacles from the skin to the glenoid rim, and all cases had a normal labrum at the 4-o'clock position. US images of the normal labrum showed that the labrum was continuously connected to the glenoid rim with no borderline (low-echo line) between them. Preoperative US from the axilla was performed in 75 patients who underwent arthroscopic surgery. Anteroinferior labra were classified preoperatively from the US images as normal, detached (low-echo line between glenoid rim and labrum), or displaced (labrum displaced from glenoid rim), with a diagnosis of a Bankart lesion being made for the latter two types. US findings were correlated with arthroscopic observations. This revealed that for the detection of Bankart lesions, US had a sensitivity of 88.6%, a specificity of 77.4%, an accuracy of 84.0%, a positive predictive value of 84.8%, and a negative predictive value of 82.8%. These results demonstrate that US with an axillary approach is useful in the diagnosis of Bankart lesions of the shoulder.     

Imaging techniques in the management of chronic kidney disease: current developments and future perspectives

The measurement of both renal function and structure is critical in clinical nephrology to detect, stage, and monitor chronic kidney disease (CKD). Current imaging modalities especially ultrasound (US), computed tomography, and magnetic resonance imaging (MRI) provide adequate information on structural changes but little on functional impairment in CKD. Although not yet considered first-line procedures for evaluating patients with renal disease, new US and MR imaging techniques may permit the assessment of renal function in the near future. Combined with established imaging techniques, contrast-enhanced US, dynamic contrast-enhanced MRI, blood oxygen level dependency MRI, or diffusion-weighted imaging may provide rapid, accurate, simultaneous, and noninvasive imaging of the structure of kidneys, macrovascular and microvascular renal perfusion, oxygenation, and glomerular filtration rate. Recent developments in molecular imaging indicate that pathophysiological pathways of renal diseases such as apoptosis, coagulation, fibrosis, and ischemia will be visualized at the tissue level. These major advances in imaging and developments in hardware and software could enable comprehensive imaging of renal structure and function in four dimensions (three dimensions plus time), and imaging is expected to play an increasing role in the management of CKD.     

Ultrasound in the study and monitoring of osteoarthritis

This review addresses the use of ultrasound (US) as an imaging technique for the evaluation and monitoring of the osteoarthritic joint. US complements both the clinical examination and radiological imaging by allowing the rheumatologist to recognize not only the bony profile but also to visualize the soft tissues. Systematic US scanning following established guidelines can demonstrate even minimal abnormalities of articular cartilage, bony cortex and synovial tissue. US is also extremely sensitive in the detection of soft tissue changes in the involved joints including the proliferation of the synovium and changes in the amount of fluid present within the joint. Monitoring the amount of fluid in the hip and knee joint with osteoarthritis may be a potentially useful finding in the selection of patients for clinical investigation and for assessing their response to therapeutic interventions.     

Magnetic resonance imaging of the thyroid, thymus, and parathyroid glands

Magnetic resonance (MR) images of the neck were obtained in 16 patients with use of a variety of spin echo and inversion recovery pulse sequences. Anatomic resolution was best with high-resolution spin echo images obtained with the pulse sequence repetition rate equal to 2.0 seconds and the echo delay equal to 28 msec because this imaging technique offered excellent contrast between normal tissues and had the highest signal noise ratio. The spatial resolution of MR was nearly as good as state of the art computerized tomography (CT). However, streak artifacts caused by motion and x-ray beam hardening often limited CT but did not affect MR. Tumors and lymph nodes were more easily differentiated from muscle and blood vessels with MR than with CT because of the superior soft-tissue contrast of MR. Tissue characterization allowed MR differentiation of thyroid nodules, thyroid cysts, and parathyroid tumors from normal thyroid tissue. Thyroid cyst fluid had the greatest water content and longest T1 and T2 relaxation times of all tissues studied. However, nonspecifically increased T1 and T2 relaxation times overlapped for a variety of neoplastic and inflammatory conditions. With further experience, MR imaging is likely to become a useful technique for the evaluation of neck masses.     

Aesthetic surgery: realities of virtuality. On the influence of images, new information and communication technologies, and the internet

Communication using images proves to be the superior way to persuade audiences. Thus, in cosmetic surgery, images are widely used to inform and to lure consumers. The superpower of visual communication is being bolstered by viewers' credulity, who never call into question the authenticity of photos as long as those photos are credible. Colorful digital images are broadcasted among scientific meetings, displayed in medical offices, and posted on the Internet. They generate a virtual world where cosmetic surgery is idealized: plastic surgeons are talented and handsome, operations are successful, and complications do not occur. We consider that digital imaging and the Internet should serve as a means to provide information that will ultimately strengthen the surgeon-patient relationship.     

Interactive images in the operating room

Fluoroscopy has made endourology possible, but its two dimensionality and poor tissue contrast limit its applications. Recent advances in computer technology are making it possible for surgeons to interact with three-dimensional CT and MR images. Initial interactive navigation systems tracked the position of surgical instruments on previously acquired images using optical, ultrasonic, or electromagnetic devices. More recently, real-time imaging and instrument tracking have become possible, such as with the open interventional MR scanners. The problems created by patient motion and tissue deformation during manipulation may thereby be overcome.     

Diagnostic imaging of the rotator cuff

The importance of imaging modalities in the evaluation of the rotator cuff has increased thanks to the development of non-invasive methods. An optimum application of the technique, appreciation of the anatomical details and imaging pitfalls, and proper interpretation of clinical findings should be incorporated in order to increase diagnostic accuracy. Ultrasonography (US) and magnetic resonance imaging (MRI) are commonly used for rotator cuff pathologies. The former has a high diagnostic accuracy in full-thickness tears, but requires operator dependency and long-term training. Both US and MRI require sophisticated equipment and present difficulties in distinguishing between partial and small full-thickness tears. In full-thickness tears, MRI may be more appropriate if imaging findings are likely to alter the course of surgical treatment. However, it is not necessary in patients in whom US may clearly show tendinosis. Magnetic resonance imaging or MR arthrography may be required in order to evaluate partial tears or suspicious small full-thickness tears in patients unresponsive to conservative therapy. A close collaboration is essential between the radiologist and the shoulder surgeon in the interpretation of clinical findings. The diagnostic accuracy will increase if the examinations are performed by a musculoskeletal radiologist.     

Computer use in filing urological images and data by MEDISYS

Summary The MEDISYS program runs on IBM-compatible microcomputers equipped with a disk operating system (MicroSoft, MS/DOS) as well as in a local network. It enables direct input of data in real time using mnemonic codes and provides the urologist with complete computerized files, statistical analysis, and automatically written reports. The integration of a videoframe grabber makes the images directly available on the computer display, like other data. Input of the images can be achieved either directly from the imaging device [e.g., ultrasound (US), computerized tomographic (CT) scan] or by using a small video camera for transparent film and paper images [e.g., US, Magnetic Resonance Imaging (MRI), scintigraphy]. The images are saved and classified according to their type [e.g., intravenous pyelogram (IVP), US]; their date; and their codes, indicating diagnosis, possible previous treatment, and the main pathologic features indicated by the image. These images, which can be modified through various functions, are available not only in the patient's file, from which they can be displayed within a few seconds, but also in an image bank that can be analyzed, which constitutes a new and powerful tool for teaching. The cost of the equipment remains moderate.     

Initial clinical experience with real-time transrectal ultrasonography-magnetic resonance imaging fusion-guided prostate biopsy

OBJECTIVE

To evaluate the feasibility and utility of registration and fusion of real‐time transrectal ultrasonography (TRUS) and previously acquired magnetic resonance imaging (MRI) to guide prostate biopsies.

PATIENTS AND METHODS

Two National Cancer Institute trials allowed MRI‐guided (with or with no US fusion) prostate biopsies during placement of fiducial markers. Fiducial markers were used to guide patient set‐up for daily external beam radiation therapy. The eligible patients had biopsy‐confirmed prostate cancer that was visible on MRI. A high‐field (3T) MRI was performed with an endorectal coil in place. After moving to an US suite, the patient then underwent TRUS to visualize the prostate. The US transducer was equipped with a commercial needle guide and custom modified with two embedded miniature orthogonal five‐degrees of freedom sensors to enable spatial tracking and registration with MR images in six degrees of freedom. The MRI sequence of choice was registered manually to the US using custom software for real‐time navigation and feedback. The interface displayed the actual and projected needle pathways superimposed upon the real‐time US blended with the prior MR images, with position data updating in real time at 10 frames per second. The registered MRI information blended to the real‐time US was available to the physician who performed targeted biopsies of highly suspicious areas.

RESULTS

Five patients underwent limited focal biopsy and fiducial marker placement with real‐time TRUS‐MRI fusion. The Gleason scores at the time of enrolment on study were 8, 7, 9, 9, and 6. Of the 11 targeted biopsies, eight showed prostate cancer. Positive biopsies were found in all patients. The entire TRUS procedure, with fusion, took ≈10 min.

CONCLUSION

The fusion of real‐time TRUS and prior MR images of the prostate is feasible and enables MRI‐guided interventions (like prostate biopsy) outside of the MRI suite. The technique allows for navigation within dynamic contrast‐enhanced maps, or T2‐weighted or MR spectroscopy images. This technique is a rapid way to facilitate MRI‐guided prostate therapies such as external beam radiation therapy, brachytherapy, cryoablation, high‐intensity focused ultrasound ablation, or direct injection of agents, without the cost, throughput, or equipment compatibility issues that might arise with MRI‐guided interventions inside the MRI suite.     

Usefulness of the 3-Dimensionally Reconstructed Computed Tomography Imaging for Diagnosis of the Site of Tracheal Injury (3D-Tracheography)

Computed tomography (CT) has not been considered useful for early diagnosis of traumatized patients who could hardly hold their breath, particularly patients with tracheal injuries. However, the recent development of spiral CT has made it possible to acquire contiguous patient data, which eliminates the respiratory misregistration. Air is easily differentiated from surrounding tissues by striking contrast, and the trachea can therefore be well displayed by three-dimensional (3D)-CT. We consider that it is possible to show tracheal injury by 3D-CT. The aim of this study is to clarify the usefulness of 3D-CT for detecting the injury site of blunt tracheal injuries. The study was carried out in hemodynamically stable patients who were suspected of having tracheal injury based on clinical manifestations such as hemoptysis, or cervical subcutaneous, deep cervical, or mediastinal emphysema. Repeated bronchoscopy confirmed tracheal injury. The virtual images of the 3D-CT (3D-tracheography) were compared with the direct images of bronchoscopic findings. Five cases were examined. In patients with tracheal injury, bronchoscopy revealed laceration of the tracheal lumen or disruption and dislocation of the tracheal cartilage, partially coated by mucus and clot, findings that confirmed the diagnosis of tracheal injury. The virtual images of the 3D-tracheography clearly showed the injury as a defect in the tracheal wall or a depression in the wall. The site and size of injury shown in the 3D-tracheography were comparable with those detected by bronchoscopy. We succeeded in detecting tracheal injuries by 3D-CT imaging, the virtual images of which were comparable with the bronchoscopic findings. 3D-tracheography is a useful method for diagnosing the site and form of tracheal injury in hemodynamically stable patients.     

Intraoperative angiography and endovascular ultrasound imaging.

Endovascular ultrasound imaging is a new technique that can be used to monitor intraoperatively the effects of balloon angioplasty or to inspect the quality of vascular reconstruction, such as endarterectomy or bypass surgery. The technique is based on high frequency ultrasonic imaging (30-40 MHz) using a rotating single element transducer mounted in an 8F catheter tip, providing 360 degrees cross-sectional real time images. The clinical application is based on the high correlation between the ultrasonic images and the histological characteristics of the corresponding vessel wall tissue and lumen geometry, as has been established in previous in vitro studies. Endovascular ultrasound assessment of percutaneous angioplasty procedures or intraoperative vascular reconstruction has become an adjunct to angiographic and/or angioscopic monitoring.     

Intraoperative cardiac assessment with transesophageal echocardiography for decision-making in cardiac anesthesia

Transesophageal echocardiography is an invaluable hemodynamic monitoring modality. Extended and anatomically based evaluation of cardiac function with transesophageal echocardiography is essential to prompt and accurate decision-making in anesthetic management during cardiac surgery. Fractional shortening and fractional area changes are indices widely used to assess the global systolic performance of the left ventricle. Monitoring regional function using semi-quantitative scoring has been demonstrated to be a more sensitive indicator of myocardial ischemia. Assessment of left ventricular diastolic function should be performed in a systematic way, measuring transmitral flow, pulmonary venous flow, transmitral color M-mode flow propagation velocity, and mitral annulus tissue Doppler imaging. The unique anatomical features of the right ventricle make echocardiographic evaluation complicated and therefore less frequently employed. Right ventricular fractional area change, tricuspid annular plane systolic excursion, maximal systolic tricuspid annular velocity with tissue Doppler imaging, and myocardial performance index are indices successfully incorporated into intraoperative right ventricular assessment. Left ventricular outflow tract obstruction with systolic anterior motion of the mitral valve may develop after cardiac procedures. Transesophageal echocardiography plays a central role in prevention as well as diagnosis of systolic anterior motion. Transesophageal echocardiography is extremely useful not only for detecting and locating intracardiac air, but also for guiding and evaluating the procedures to remove air. Air is likely to persist in the right and left superior pulmonary vein, left ventricular apex, left atrium, right coronary sinus of Valsalva, and ascending aorta. Accurate evaluation of cardiac function depends on performing TEE examination properly and obtaining optimal images.     

Physics of ultrasound

Ultrasound is a form of non-ionizing radiation that uses high-frequency sound waves to image the body. It is a real-time investigation which allows assessment of moving structures and also facilitates measurement of velocity and directionality of blood flow within a vessel. It can be used for a variety of purposes in the intensive care setting, for example to aid central venous catheter and pleural drain insertion. When using this imaging modality it is vital to understand the relevant physical principles and how the images are created. This article will explain these principles, including the use of Doppler ultrasound and the interpretation of common artefacts.     

Burn imaging with a whole field laser Doppler perfusion imager based on a CMOS imaging array

Laser Doppler perfusion imaging (LDPI) has been proven to be a useful tool in predicting the burn wound outcome in an early stage. A major disadvantage of scanning beam LDPI devices is their slow scanning speed, leading to patient discomfort and imaging artifacts. We have developed the Twente Optical Perfusion Camera (TOPCam), a whole field laser Doppler perfusion imager based on a CMOS imaging array, which is two orders of magnitude faster than scanning beam LDPI systems. In this paper the first clinical results of the TOPCam in the setting of a burn centre are presented. The paper shows perfusion images of burns of various degrees. While our system encounters problems caused by blisters, tissue necrosis, surface reflection and curvature in a manner similar to scanning beam imagers, it poses a clear advantage in terms of procedure time. Image quality in terms of dynamic range and resolution appears to be sufficient for burn diagnosis. Hence, we made important steps in overcoming the limitations of LDPI in burn diagnosis imposed by the measurement speed.     

Propylene glycol as a contrasting agent for optical coherence tomography to image gastrointestinal tissues

BACKGROUND AND OBJECTIVE: Optical coherence tomography (OCT) is a recently developed imaging technique that has the potential to advance the early diagnosis of diseases in the human gastrointestinal (GI) tract. How ever, the high scattering nature of GI tissue limits its imaging depth and contrast. For more effective diagnosis using OCT, a concurrent improvement of imaging depth and contrast is, therefore, needed. In this work, we investigate the administration of chemical agents to the tissue as a means of improving the capability of OCT imaging of clinically relevant microstructures of the GI tract. STUDY DESIGN/MATERIALS AND METHODS: Normal human GI tissues, including stomach and oesophagus were obtained from patients in hospital, and were imaged with OCT within 0.5-2 hours of removal. Immediately after the first imaging of the specimens with OCT, about 0.5 ml of 80% propylene glycol solution was applied onto the tissue surface and the tissue allowed to absorb the chemical compounds for 20 minutes. Another image was then taken at the same position. The specimens were then embedded and stained in preparation for histologic evaluation. Co-registration of the images obtained using OCT before and after the topical application of the propylene glycol solution, and standard histopathologic processing provided basis for comparison. RESULTS: More detailed micro-structures, including the basal layer position and the cellular composition of the mucosal layer of GI tract tissues were observed after the topical application of propylene glycol solution, while these structures were not resolvable in the conventional OCT images. CONCLUSIONS: Propylene glycol could be used as a contrasting agent for OCT imaging of human GI tract tissues, allowing an increased capability of OCT for rapid clinical diagnosis in vivo.     

Soft tissue chondroma presenting as a painful finger: diagnosis by magnetic resonance imaging.

Benign cartilage tumors of the hands and feet are uncommon soft tissue tumors that generally present as a painless swelling. The diagnosis is often made histologically, as the radiographic appearance of the soft tissues may be normal. In this report, we present a woman who demonstrates the need to consider soft tissue chondromas in the differential diagnosis of a painful finger. Magnetic resonance imaging was used to localize the tumor, suggesting that this imaging method may be useful in differential diagnosis of finger pain.