PubMed Health⌕ Search

Biomedical subjects

C W Piccoli

Publications and source records attributed to C W Piccoli.

15 recordsLinked to original sources
PubMed1998

Comparisons of the Rayleigh and K-distribution models using in vivo breast and liver tissue.

There is a strong interest in finding out which statistical model is the most appropriate for describing the envelope of the backscattered ultrasonic echoes from different types of tissues. The Rayleigh model is commonly employed, but this requires conditions, such as the presence of large number of randomly located scatterers with fairly uniform cross-sections, that are not always met. However, our research indicates that a model based on the K-distribution may provide a better fit to empirical data over a range of scattering conditions than the standard Rayleigh model. In this study, we looked at the K-distribution as a descriptor of the backscattered envelope of the breast and liver tissues (in vivo). By examining data from various tissue regions, a goodness-of-fit test (a least squares error method) was used to determine whether a Rayleigh or K-distribution model is more appropriate. From a large group of patients and volunteer scans (a total of 72 subjects), the fit between the K-distribution and the data is shown to have a much smaller error than the Rayleigh model.

Adult↗
PubMed1997

Contrast-enhanced breast MRI: factors affecting sensitivity and specificity.

Contrast-enhanced MRI (CE-MRI) of the breast has been investigated for over 10 years. The reports of sensitivity for cancer detection have generally been greater than 90 %. However, estimates of specificity have varied greatly. Differing results are due to differences in study populations, technical methods and criteria for interpretation. Early and marked signal rise, detected using dynamic imaging technique following contrast administration, is the MRI hallmark of cancer. However, some malignant lesions may enhance slowly or minimally, and a variety of benign lesions may enhance rapidly with marked signal intensity. High resolution techniques generally requiring longer acquisition times are more likely to depict the slowly enhancing malignancies at the cost of a decrease in specificity due to lack of temporal resolution. This disadvantage may be offset by the improved visualization of lesion morphology with high resolution images. This report reviews the methods and results of the leading investigators of breast MRI.

Breast Neoplasms↗
PubMed1996

Studies on the use of non-Rayleigh statistics for ultrasonic tissue characterization.

The research groups at Drexel University and Thomas Jefferson University had proposed the use of non-Rayleigh statistics for tissue characterization. Previous work based on the hypothesis that the envelope of the backscattered echosignal from abnormal regions of the tissue is more likely to be K-distributed than Rayleigh distributed, used the parameter of the K-distribution, M, to distinguish between regions containing benign or malignant masses and normal ones. In this work the B-scan breast images of 19 patients were studied using this approach. Previous studies have also been extended to exploit the existence of non-uniform phase characteristics of the echosignal from scatterers with some regular spacings, such as those in a periodic or quasi-periodic alignment. Computer simulations were carried out to show that the phase statistics deviate significantly from uniform in the range of (0, 2 pi) if the imaging region contained a number of periodically aligned (regular lattice) scatterers along with a collection of randomly distributed scatterers resulting in a quasi-periodic arrangement. This methodology was then applied to B-scan images of the breasts to distinguish between benign and malignant masses. If benign lesions show some sort of quasi-periodic or regular structures in the tissue, they will present non-uniform phase characteristics while more randomly structured malignant masses will have uniform phase characteristics. It is seen that the K-distribution may be used to identify the abnormal regions in the breast images and information on the phase may be used to further separate the abnormal regions into benign and malignant ones.

Breast Neoplasms↗
PubMed1996

Breast imaging.

Explore the source record for details and available documents.

Breast Neoplasms↗
PubMed1996

Ultrasonography.

Explore the source record for details and available documents.

Humans↗
PubMed1995

MR imaging: quality assessment method and ratings at 33 centers.

PURPOSE: To outline a quality assessment method with peer review for magnetic resonance (MR) imaging. MATERIALS AND METHODS: Thirty-three providers in the Philadelphia area were rated on a random sample of 132 brain, 124 cervical spine, and 113 lower extremity MR imaging examinations performed during 1990. Blinded peer review was performed by panels of three subspecialty-trained academic radiologists. Technical performance, completeness, and report appropriateness of each MR imaging examination were evaluated. Aggregated scores were calculated to rate provider performance for each of the three parameters of quality. RESULTS: Two or three panelists assessed technical performance as inadequate in 15 cases, completeness as incomplete in 58 cases, and the interpretative report as inappropriate and affecting treatment in 72 cases. Eleven providers received an unsatisfactory rating on one or more parameters of quality. The association between unsatisfactory ratings and the use of low-field-strength (< or = 0.6-T) imagers was statistically significant (P < .008). CONCLUSION: Substantial deficiencies were identified in the performance of examinations and interpretation of MR images in the Philadelphia area in 1990. These findings indicate the need for a program to monitor quality of MR imaging.

Brain↗
PubMed1995

Distinction between benign and malignant adrenal masses: value of T1-weighted chemical-shift MR imaging.

OBJECTIVE: Accuracy of T1-weighted chemical-shift MR imaging for the differentiation between benign and malignant adrenal masses was blindly assessed among three radiologists. SUBJECTS AND METHODS: MR imaging was performed at 1.5 T in 50 patients with 58 adrenal masses, proved benign (n = 38) or malignant (n = 20) based on surgery or growth (malignant) or stable size (benign) for at least 1 year. In-phase spin-echo sequences or in-phase breath-hold fast multiplanar spoiled gradient-recalled echo (FMPSPGR) sequences with a TE of 4.2 msec were compared with opposed-phase breath-hold FMPSPGR sequences with a TR/TE of 35-155/2.2-2.9 and a 90 degrees flip angle for the detection of lipid in adrenal masses. Three radiologists who were blinded to diagnosis and clinical data independently rated the likelihood of a benign adrenal lesion on a five-point scale of confidence. RESULTS: Mean sensitivity, specificity, and positive predictive value for a definite or probable diagnosis of a benign lesion by the three readers were 87%, 92%, and 95%, respectively. At the highest (definite) confidence of a benign lesion, the mean positive predictive value was 99%, with lower sensitivity (54%). Areas under receiver operating characteristic curves for the three radiologists were .98 (95% confidence interval [CI] = .94-1.00), .96 (CI = .91-1.00), and .95 (CI = .89-1.00). Interobserver variation for the diagnosis of a benign mass was low (kappa = .79). CONCLUSION: Chemical-shift imaging using breath-hold opposed-phase T1-weighted MR images is a reliable and reproducible technique for the diagnosis of most benign adrenal masses at the highest threshold of confidence.

Adrenal Gland Neoplasms↗
PubMed1994

Staging of prostate cancer: results of Radiology Diagnostic Oncology Group project comparison of three MR imaging techniques.

PURPOSE: To assess accuracy of three different magnetic resonance (MR) imaging techniques, including the endorectal coil, in staging prostate cancer. MATERIALS AND METHODS: MR imaging was performed in 213 patients with prostate cancer with a conventional body coil, with fat suppression and a body coil, and with an endorectal coil. Radiologists identified tumor invasion into periprostatic tissues, neurovascular bundles, and seminal vesicles. Each technique was evaluated separately, and in a subset of 74 patients the three techniques were evaluated together. Images obtained with the two body-coil techniques were read in combination with images obtained with the endorectal coil (combination A) and alone (combination B). RESULTS: Overall accuracy for conventional body-coil, fat-suppressed body-coil, and endorectal-coil MR was 61%, 64%, and 54%, respectively. Overall group accuracy for combinations A and B was 57% and 61%. Considerable interreader variability was found for combination A. CONCLUSION: No technique was highly accurate for staging early prostate cancer. Individual radiologists did achieve a high degree of staging accuracy with the endorectal-coil and body-coil combination.

Humans↗
PubMed1994

The specificity of contrast-enhanced breast MR imaging.

The sensitivity of contrast-enhanced breast MR imaging for malignancy is close to 100%, an improvement over traditional methods of cancer detection. The reported specificity of breast MR imaging, however, ranges from approximately 37% to 97%. This range of values is the result of differences in technique and diagnostic criteria. The variation in biologic activity and vascularity of benign and malignant lesions, as well as normal tissue, also complicates MR imaging diagnosis. A review of breast MR imaging research with an emphasis on specificity issues is also presented.

Breast↗
PubMed1992

Current utilization and future techniques of breast ultrasound.

The role of breast sonography has been well defined as a supplement to clinical examination and mammography, but investigative attempts at refining and expanding that role continue. Several recent articles correlate pathologic results with either subjective or objective B-mode findings. The results of these investigations corroborate the conclusions of previous studies, particularly the conclusion that sonography has value in the differentiation of cystic from solid masses. Interest in Doppler ultrasound increased as color flow imaging became widely available, and recent work suggests potential for diagnostic differentiation of solid masses using Doppler technique.

Breast Neoplasms↗
PubMed1990

Magnetic resonance imaging of the prostate and bladder.

Prostate carcinoma is the most common cancer in men and the second most lethal malignancy among the American male population. Nevertheless, it is potentially curable if detected early and treated appropriately. Treatment options vary depending on the extent (stage) of the cancer. MRI has no role as a screening method for prostatic carcinoma because it is expensive, time consuming, and unable to differentiate benign from malignant disease, but it can detect early prostatic cancers in patients with known tumor and can accurately stage these tumors. MRI is becoming the imaging modality of choice for local staging of prostate cancer and is rapidly replacing CT and ultrasonography for this purpose. Treatment protocols for bladder carcinoma also depend on the stage of the tumor. Clinical staging of bladder cancer has been limited. MRI is as good as or better than CT in bladder tumor staging when extravesical tumor involvement is present. MRI also has the potential to become useful in determining the depth of wall invasion in tumors confined to the bladder.

Female↗
PubMedDate not supplied

MR portography: preliminary comparison with CT portography and conventional MR imaging.

Magnetic resonance (MR) imaging with arterial portography (MRAP) was compared with computed tomography with arterial portography (CTAP) and conventional MR imaging for preoperative evaluation of hepatic masses in eight patients (nine studies). Twenty contiguous, 10-mm-thick-section CTAP images were obtained. MR imaging included T1- and T2-weighted spin-echo and fast multiplanar SPGR (spoiled gradient-recalled acquisition in the steady state) techniques. For MRAP, 0.1 mmol/kg gadopentetate dimeglumine was injected into the superior mesenteric artery. Portographic-phase, 8-mm-thick-section, axial SPGR images were first obtained, followed by "systemic phase" SPGR images. Lesions were seen best on the portographic-phase MRAP images and were less conspicuous on the systemic-phase MRAP, CTAP and conventional MR images. Of 19 visualized lesions, 18 were seen with MRAP; however; five subcentimeter lesions seen with MRAP were not seen with conventional MR imaging or CTAP. Systemic recirculation of iodinated contrast material from the bolus and from previous angiography is a potential limitation of CTAP. For both CTAP and MRAP, optimal results are expected if all images are obtained during a single breath hold, within seconds of the onset of contrast agent administration.

Contrast Media↗
PubMedDate not supplied

MRI of benign and malignant hepatic lobar atrophy.

We assessed the magnetic resonance imaging (MRI) features of hepatic lobar atrophy. Two of us reviewed MRIs of the liver in eight patients with benign or malignant forms of lobar atrophy. All atrophic lobes showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images compared with the remainder of the liver, and all showed greater enhancement compared to the nonatrophic lobe. Atrophic lobes have suggestive MRI findings and are similar for both benign and malignant etiologies.

Adult↗