Testing telediagnostic thyroid ultrasound in Peru: a new horizon in expanding access to imaging in rural and underserved areas.

PURPOSE: Thyroid ultrasound is a key tool in the evaluation of the thyroid, but billions of people around the world lack access to ultrasound imaging. In this study, we tested an asynchronous telediagnostic ultrasound system operated by individuals without prior ultrasound training which may be used to effectively evaluate the thyroid and improve access to imaging worldwide. METHODS: The telediagnostic system in this study utilizes volume sweep imaging (VSI), an imaging technique in which the operator scans the target region with simple sweeps of the ultrasound probe based on external body landmarks. Sweeps are recorded and saved as video clips for later interpretation by an expert. Two operators without prior ultrasound experience underwent 8 h of training on the thyroid VSI protocol and the operation of the telemedicine platform. After training, the operators scanned patients at a health center in Lima. Telediagnostic examinations were sent to the United States for remote interpretation. Standard of care thyroid ultrasound was performed by an experienced radiologist at the time of VSI examination to serve as a reference standard. RESULTS: Novice operators scanned 121 subjects with the thyroid VSI protocol. Of these exams, 88% were rated of excellent image quality showing complete or near complete thyroid visualization. There was 98.3% agreement on thyroid nodule presence between VSI teleultrasound and standard of care ultrasound (Cohen's kappa 0.91, P < 0.0001). VSI measured the thyroid size, on average, within 5 mm compared to standard of care. Readers of VSI were also able to effectively characterize thyroid nodules, and there was no significant difference in measurement of thyroid nodule size (P = 0.74) between VSI and standard of care. CONCLUSION: Thyroid VSI telediagnostic ultrasound demonstrated both excellent visualization of the thyroid gland and agreement with standard of care thyroid ultrasound for nodules and thyroid size evaluation. This system could be deployed for evaluation of palpable thyroid abnormalities, nodule follow-up, and epidemiological studies to promote global health and improve the availability of diagnostic imaging in underserved communities.

Interleukin-2 induces profound reversible cholestasis: a detailed analysis in treated cancer patients.

Interleukin-2 (IL-2)-based immunotherapy is associated with profound reversible cholestasis and hyperbilirubinemia. We performed a nonrandomized retrospective and prospective analysis to determine the incidence, characteristics, clinical course, and nature of the IL-2-induced liver dysfunction in patients with cancer. Patients received IL-2 at a dose of 20,000 to 100,000 units (U)/kg thrice daily for up to 5 days. Fifty-one patients on adjuvant treatment protocols received a mean of 10.18 +/- 2.38 IL-2 doses and 11.67 +/- 4.16 doses were delivered to 210 patients with advanced disease during this period. Retrospective analysis of all patients receiving this therapy revealed increases in the following liver function tests expressed as median, 25th percentile, and 75th percentile (range): bilirubin (mg/dL) 4.5, 2.6, 6.5 (.4 to 38.5); alkaline phosphatase (U/L) 256, 179, 378 (56-1680); SGOT (U/L) 80, 52, 117 (18 to 483); SGPT (U/L) 91, 64, 132 (20-540); prothrombin time 13.4, 12.8, 14.5 (10.8 to 35.4); and albumin (g/dL) values decreased (trough) slightly 3.0, 2.8, 3.2 (2.3 to 3.8). Multiple regression analysis revealed several factors that were significantly associated with the increase in bilirubin when jointly considered (model P2 less than or equal to .001) including total IL-2 dosage, increase in creatinine, alkaline phosphatase, weight, and SGOT. Similar increases were noted in a prospectively evaluated group of 10 patients. A return to normal levels of bilirubin was noted within 5.6 days of stopping IL-2. Fasting serum cholylglycine increased from a mean of 32.3 +/- 1.6 to a peak of 1556.0 +/- 625.0 mg/mL. Although conventional ultrasound examinations were unrevealing, tissue ultrasound examinations revealed a mean scatterer spacing (MSS) increase compared to baseline of .10 +/- .04 (P less than .02) suggesting hepatic edema or an infiltrative process. Further, computerized hepatobiliary nuclear medicine scans revealed a delay in uptake (2.2 +/- 0.5 fold greater) and excretion (8.0 +/- 5.9 fold greater) of technetium-99m labeled disofenin. These findings support the development of profound reversible cholestasis as the primary basis for the elevated bilirubin in patients undergoing IL-2 treatment and may have implications for understanding the jaundice observed in some patients postoperatively as well as that associated with sepsis and other inflammatory disorders. Specifically, the release of IL-2 or the induction of other factors similarly induced by IL-2 may be responsible for these findings. Tissue ultrasound and computerized hepatobiliary scans provide additional noninvasive assessments of liver function and physiology.

Quantitative ultrasonic detection and classification of diffuse liver disease. Comparison with human observer performance.

A multiparameter ultrasonic tissue characterization system has been developed and tested on several types of diffuse liver disease. The four tissue characterization parameters used are based on the first and second order statistics of the B-scan image. Performance of the system was evaluated using receiver operating characteristic (ROC) analysis and was compared with the performance of experienced human observers viewing B-scan images. The machine-based multiparameter system achieved an area under the ROC curve (Az) of 0.88 for detection of chronic hepatitis in more than 100 proven cases of the disease. This was dramatically better than the performance of human observers (Az = .64, P less than .05) and compares favorably to the performance of other accepted diagnostic tests such as head CT and the PAP smear. For detection of Gaucher's disease, the Az for the system was .92, whereas for separating hepatitis from Gaucher's disease Az was .84. Human observers also did well at these tasks (P greater than .8) using organomegaly as their major criterion for diagnosing Gaucher's disease. For primary biliary cirrhosis the system Az was .80, for glycogen storage disease Az was .94. These results suggest that use of multiparameter tissue characterization can significantly increase the usefulness of ultrasound for evaluation of diffuse liver disease.

Quantitative ultrasonic detection of parenchymal structural change in diffuse renal disease.

OBJECTIVE: The authors determined whether quantitative ultrasound could be useful in the evaluation of diffuse renal disease. METHODS: Digitized radiofrequency ultrasound data were acquired from the kidneys of patients with biopsy-proven diffuse renal disease and transplant rejection (37 patients plus 18 normal volunteers). The results of the quantitative analysis were compared with histology results to determine if microscopic renal structure could be correlated with quantitative features such as scatterer size and scatterer spacing. The results also were analyzed using receiver operating characteristic analysis to determine if diffuse disease could be detected reliably using quantitative methods. RESULTS: The three most useful features in the native kidneys were mean scatterer spacing (MSS), sigma's, and average scatterer size (D). Using these features, it was possible to detect diffuse renal disease causing a decrease in renal function with an area under the ROC curve (Az) of 0.93. The feature D corresponded closely to histologically measured average glomerular diameters. For normals, D = 216 microns and glomerular diameter = 211 microns. No histologic correlate was found for scatterer spacing. In transplants, MSS and integrated backscatter were most useful for detecting rejection (Az = 0.87), and D in rejection was similar to the values for normal kidney and normally functioning transplants. CONCLUSIONS: The D value corresponds to glomerular diameter, and glomerular enlargement can be detected readily using quantitative ultrasound. Combinations of two to four quantitative features can detect diffuse renal disease and transplant rejection reliably.

Successful management of hepatic abscesses by percutaneous catheter drainage in chronic granulomatous disease.

Chronic granulomatous disease (CGD) is a disorder of polymorphonuclear leukocytes that can cause multiple recurrent hepatic abscesses in 40% of those patients with the disorder. The mortality rate from this complication of CGD is estimated at 27%. Treatment has consisted of extensive surgical debridement and drainage and prolonged antibiotic therapy; however, this approach is accompanied by high morbidity and the frequent need for reoperation. Successful percutaneous drainage of multiple hepatic abscesses in a patient who had previously undergone 10 operative procedures to manage hepatic abscesses is reported. With the development of imaging and percutaneous drainage techniques, as well as the recurrent nature of this problem, percutaneous management should be given consideration in appropriate patients with CGD with hepatic abscesses.

Biomechanical response to acupuncture needling in humans.

During acupuncture treatments, acupuncture needles are manipulated to elicit the characteristic "de qi" reaction widely viewed as essential to acupuncture's therapeutic effect. De qi has a biomechanical component, "needle grasp," which we have quantified by measuring the force necessary to pull an acupuncture needle out of the skin (pullout force) in 60 human subjects. We hypothesized that pullout force is greater with both bidirectional needle rotation (BI) and unidirectional rotation (UNI) than no rotation (NO). Acupuncture needles were inserted, manipulated, and pulled out by using a computer-controlled acupuncture needling instrument at eight acupuncture points and eight control points. We found 167 and 52% increases in mean pullout force with UNI and BI, respectively, compared with NO (repeated-measures ANOVA, P < 0.001). Pullout force was on average 18% greater at acupuncture points than at control points (P < 0.001). Needle grasp is therefore a measurable biomechanical phenomenon associated with acupuncture needle manipulation.

Quantitative sonographic feature analysis of clinical infant hypoxia: a pilot study.

PURPOSE: To determine whether textural features derived from sonographic pixel intensities differ significantly between healthy infants and infants who have had acute clinical hypoxic episodes. METHODS: Neurosonographic and calibration phantom-processed image data were evaluated prospectively from 9 infants (age range, 1 to 163 days) with at least 1 episode of hypoxia and compared with image data from a control population of 16 healthy infants (age range, 1 to 191 days). Custom software was used to make 45 textural feature measurements on 40 x 40-pixel regions of interest within brain parenchyma in the distribution of each major cerebral artery, the thalami, and the cerebellum and in a tissue-mimicking calibration phantom. Means comparison testing was followed by logistic regression to assess statistical variation between the patients and the control group. RESULTS: Nine of 45 textural features showed statistically significant differences between mean values comparing the two groups. Mean gray level was the most sensitive predictor of differences between the two populations (mean gray level for healthy subjects was 46.8; mean gray level for patients was 56.3). An average of mean gray values in areas supplied by the posterior cerebral arteries and the cerebellum was even more sensitive for differentiating healthy subjects from patients. CONCLUSIONS: Quantitative sonographic textural feature analysis showed differences between the brains of healthy infants and those of infants with clinical hypoxia.

High resolution ultrasonic backscatter coefficient estimation based on autoregressive spectral estimation using Burg's algorithm.

An autoregressive (AR) method for spectral estimation was applied toward the task of estimating ultrasonic backscatter coefficients from small volumes of tissue. High spatial resolution is desirable for generating images of backscatter coefficient. Data was acquired from a homogeneous tissue-mimicking phantom and from a normal human liver in vivo. The AR method was much more resistant to gating artifacts than the traditional DFT (discrete Fourier transform) approach. The DFT method consistently underestimated backscatter coefficients at small gate lengths. Therefore backscatter coefficient image formation will be quantitatively more meaningful if based on AR spectral estimation rather than the DFT. The autoregressive method offers promise for enhanced spatial resolution and accuracy in ultrasonic tissue characterization and nondestructive evaluation of materials.

Image staining and differential diagnosis of ultrasound scans based on the Mahalanobis distance.

The covariance matrices associated with each state of health or disease from a previous study are used as the basis of an image staining display technique for aid in quantitative differential diagnosis. A state of health or disease is chosen by the clinician: this selects the covariance matrix from the data base. A region of interest (ROI) is then scrolled through an abdominal B-scan. For each position of the ROI a point in the four-dimensional feature space is calculated. A natural measure of the distance of this point from the center of mass (multivariate mean) of the disease class is calculated in terms of the covariance matrix of this class; this measure is the Mahalanobis distance. The confidence level for acceptance or rejection of the hypothesized disease class is obtained from the probability distribution of this distance, the T(2) probability law. This confidence level is color coded and used as a color stain that overlays the original scan at that position. The variability of the calculated features is studied as a function of ROI size, or the spatial resolution of the color coded image, and it is found that for an ROI in the neighborhood of 4 cm(2) most of the variability due to the finite number of independent samples (speckles) is averaged out, leaving the "noise floor" associated with inter- and intra-patient variability. ROIs on the order of 1 cm(2) may result with technical advances in B-scan resolution. A small number of points on organ boundaries are entered by the user, to fit with arcs of ellipses to be used to switch between organ (liver and kidney) data bases as the ROI encounters the boundary. By selecting in turn various state-of-health or state-of-disease databases, such images of confidence levels may be used for quantitative differential diagnosis. The method is not limited to ultrasound, being applicable in principle to features obtained from any modality or multimodality combination.

Evaluation of STIR imaging as a complement to spin-echo MR and CT of the porta hepatis/hepatoduodenal ligament.

Short TI inversion-recovery (STIR) imaging provides specific advantages over standard spin-echo (SE) MR sequences by producing additive effects of T1 and T2 brightening of pathology and suppression of the signal from surrounding fat. We retrospectively evaluated 12 patients with abnormalities, primarily neoplastic, of the porta hepatis/hepatoduodenal ligament (PH/HdL) with CT and MR imaging, including SE and STIR imaging. Masses on CT were of slightly decreased density compared to liver and seen in contrast to surrounding fat in the PH/HdL region. On MR, T1-weighted images provided comparable anatomic detail to CT, with masses clearly distinguished from surrounding fat due to the low signal intensity of masses as compared to fat. T2-weighted images clearly depicted intrahepatic lesions because of their high signal intensity relative to liver. Increased signal in extrahepatic lesions made them less distinctly seen from surrounding fat. STIR images best demonstrated tumor relative to fat. In six cases, CT was equivalent in demonstrating pathology to the best MR sequence. At least one MR sequence demonstrated pathology better than CT in 6 of 12 cases. In five of these six cases, the STIR sequence was better than CT. Thus, MR, particularly STIR imaging, provides a useful technique in imaging of PH/HdL pathology.

Assessment of bone density using ultrasonic backscatter.

The goal of this project was to investigate the utility of ultrasonic backscatter for the assessment of bone status. Ultrasound offers a low-cost, portable, nonionizing alternative or complement to common X-ray- or radioisotope (gamma ray)-based methods of bone densitometry. Ultrasonic backscatter may provide useful information not revealed by ultrasonic attenuation and sound-speed densitometers. Backscatter is sensitive to microstructural variations in acoustic impedance and should therefore provide information regarding architecture (which is related to fracture risk), as well as density. Ultrasonic backscatter at 2.25 MHz and CT bone densitometric data have been acquired from 10 healthy human volunteers. The degree of correlation between CT and ultrasonic backscatter is high (r = 0.87, p < 0.001). The envelope signal-to-noise ratio was 1.81 +/- 0.08 (mean +/- standard deviation). This suggests that the number of scatterers per resolution cell is large, the radiofrequency signal approximately obeys circular Gaussian statistics, and the envelope obeys Rayleigh statistics. These results indicate promise for ultrasonic backscatter as a substitute for or an adjunct to other ultrasonic measurements (attenuation and sound speed) and X-ray measurements for the assessment of bone status.

PACS clinical experience at Georgetown University.

Georgetown University Hospital has been operating an image management and communications system (IMACS or PACS) for three-and-a-half years. This work was initially funded under the Army Medical Research and Development Command Digital Imaging Network Systems (DINS) project. The system was taken from a research system supporting only radiology tasks to one extended to clinical use, and has been used in clinical work for two-and-a-half years. This paper will summarize our PACS clinical experience and will describe the operational features implemented and those still necessary.

Elastography: ultrasonic estimation and imaging of the elastic properties of tissues.

The basic principles of using sonographic techniques for imaging the elastic properties of tissues are described, with particular emphasis on elastography. After some preliminaries that describe some basic tissue stiffness measurements and some contrast transfer limitations of strain images are presented, four types of elastograms are described, which include axial strain, lateral strain, modulus and Poisson's ratio elastograms. The strain filter formalism and its utility in understanding the noise performance of the elastographic process is then given, as well as its use for various image improvements. After discussing some main classes of elastographic artefacts, the paper concludes with recent results of tissue elastography in vitro and in vivo.

Gallbladder imaging. The state of the art.

Cholelithiasis and its sequelae are readily identified by the myriad imaging techniques available. Understanding the technical issues and correlation of specific findings with the clinical symptoms is essential for accurate diagnosis.

Gallstone lithotripsy: relevant physical principles and technical issues.

A basic understanding of shock wave generation is essential for the radiologist who performs gallstone lithotripsy. Shock waves differ from ordinary acoustic waves in that they have a rapid rise time, a positive pressure component that gives rise to compressive forces approaching 1,000 atm, and a low-amplitude sustained negative pressure (rarefactive) component. Shock waves are created by means of three different types of shock wave generators: spark-gap, electromagnetic, and piezoelectric. The authors describe and compare these three types of shock wave generators with regard to equipment selection. Regardless of how shock waves are generated, they share common interactions with tissue. These interactions are reviewed along with the proposed mechanisms of stone fragmentation.

Scrotal-inguinal ultrasonography: a technique for identifying the nonpalpable inguinal testis without laparoscopy.

PURPOSE: Treatment of the patient with a nonpalpable testis is controversial, since a high percent will have an inguinal testis or testicular remnant at exploration. While laparoscopy is an effective modality for localizing the intra-abdominal testis, diagnostic laparoscopy is of limited value for patients with nonpalpable (normal or atrophic) inguinal testes. In an effort to identify preoperatively impalpable inguinal testes, we performed scrotal-inguinal ultrasound. MATERIALS AND METHODS: We evaluated 64 patients (74 nonpalpable testes) in the last 4 years, representing 20% of all those presenting with cryptorchidism. Average patient age was 4.5 years (range 6 months to 17 years). All patients underwent preoperative scrotal-inguinal ultrasound and surgical exploration. Diagnostic laparoscopy was reserved for patients with negative ultrasound and no palpable tissue in the scrotum or groin on a preoperative examination. RESULTS: Scrotal-inguinal ultrasound correctly identified 40 of the 42 inguinal testes (95% sensitivity), 7 of the 21 atrophic inguinal testes (33% sensitivity) and 1 of the 11 intra-abdominal testes (9% sensitivity). Therefore, scrotal-inguinal ultrasound correctly identified an inguinal testis or remnant for 47 of the 74 nonpalpable testes (64%), eliminating the need for diagnostic laparoscopy in those cases. For 26 of 74 nonpalpable testes with negative ultrasound 13 had an associated palpable inguinal or scrotal nubbin of tissue, and inguinal exploration only was performed, resulting in 9 orchiectomies, 2 inguinal orchiopexies and 2, 2-stage orchiopexies. Of the 13 nonpalpable testes without palpable nubbins and negative scrotal-inguinal ultrasound 8 were intra-abdominal and 5 were atrophic inguinal testes. CONCLUSIONS: Scrotal-inguinal ultrasound identifies patients with nonpalpable testes who will maximally benefit from diagnostic laparoscopy. When diagnostic laparoscopy was limited to nonpalpable testes without palpable nubbins and negative scrotal-inguinal ultrasound, only 13 of 74 (18%) required laparoscopy. Inguinal exploration without further diagnostic studies is appropriate for boys with nonpalpable testes and palpable nubbins.

Measurements of ultrasonic backscatter coefficients in human liver and kidney in vivo.

Ultrasonic backscatter coefficients, in the range of 2.0-4.0 MHz, were measured in normal human livers and kidneys in vivo. In liver, data were acquired and analyzed from 15 normal volunteers and 19 patients with hepatitis. No significant difference between normal and chronic hepatitis was found. The power-law fit to the backscatter coefficient in normal liver as a function of frequency was eta(f) = 4.5 x 10(-5) f1.6 cm-1 Str-1. This is comparable to that measured by other investigators in in vitro preparations of human and animal liver and to that measured by two other teams of investigators in in vivo human liver. In kidney, data were acquired from 11 normal volunteers. The power-law fit to the backscatter coefficient in normal kidney was eta (f) = 2.3 x 10(-5) f2.1 cm-1 Str-1. This is in the range of that measured by other investigators in in vitro preparations of human and animal kidney. In order to assess the system dependence of in vivo abdominal organ backscatter coefficients, measurements were performed using two different ultrasonic data-acquisition systems. The two systems exhibited close agreement.

Ultrasound appearance of extramedullary hematopoiesis.

Extramedullary hematopoiesis accompanies a wide variety of diseases and is defined as the abnormal production of blood outside the normal confines of the bone marrow. Most of the time, extramedullary hematopoiesis is found as microscopic foci in soft tissues; however, on occasion this process may reach a size that is detectable with ultrasound. Two forms are possible: "paraosseous"--in which the normal medullary tissue of the bone marrow ruptures through the bone to present as a paraosseous soft tissue mass,--and "extraosseous"--in which extramedullary hematopoiesis occurs within soft tissue. These "masses" of hematopoietic tissue can appear almost anywhere in the abdomen and pelvis and can mimic a wide variety of more serious diseases.

US tissue characterization workstation: applications and design.

This article discusses the purpose, design, and uses of an ultrasonographic tissue characterization workstation. The distinguishing characteristic of a tissue characterization workstation is its ability to analyze and classify image textures. Texture is defined as regularly or randomly repeating patterns. Small texture differences in an image are difficult to observe in the presence of noise. Therefore, it is necessary to analyze the image quantitatively. Quantitative measurements include run-length statistics, fractal dimension, and correlation statistics. The workstation is designed so that a radiologist can analyze the patient's images through an easy-to-use graphical user interface. The workstation software is based on standards, so that it can be run on a variety of different hardware platforms. The workstation can be used in a research environment to distinguish between images of malignant and benign breast lesions, which are difficult to diagnose visually. Further work is being done to make the workstation software into a useful clinical tool.