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Biomedical subjects

Harpreet K Pannu

Publications and source records attributed to Harpreet K Pannu.

At least 19 recordsLinked to original sources
PubMed2006

Beta-blockers for cardiac CT: a primer for the radiologist.

OBJECTIVE: The objective of this article is to describe a protocol for the administration of beta-blockers for cardiac CT. A low and regular heart rate is necessary for optimal visualization of the coronary arteries on CT and can be achieved by the administration of medications. CONCLUSION: Beta-blockers can be safely given, orally or IV, to most patients to lower the heart rate for cardiac CT. A protocol can be implemented and patients can be screened for certain contraindications to allow successful administration of these medications by radiologists.

Adrenergic beta-Antagonists↗
PubMed2006

Coronary CT angiography with 64-MDCT: assessment of vessel visibility.

OBJECTIVE: The objective of our study was to evaluate the image quality of 64-MDCT for coronary angiography. SUBJECTS AND METHODS: Fifty consecutive CT coronary angiograms obtained on a 64-MDCT scanner were independently reviewed by two reviewers. Segments were scored as showing no motion (score of 1), minimal motion (2), moderate motion (3), respiratory motion (4), or vessel blurring (5). Opacification was graded as good (score of 1) or limited (2). Segments < 2 mm were graded as well seen; or as poorly seen or not seen. The scores for motion artifact, opacification, and visibility were combined for overall vessel assessment. Segments with a motion score of 1 or 2 that had good opacification and were well seen were judged to be assessable. RESULTS: A total of 714 segments were analyzed in 50 patients. Seven hundred segments were assessed in all patients (segments 1-3, 11-20, 4, or 27), and a ramus intermedius segment was evaluated in 14 patients. Combining the scores for both reviewers, the average motion score was 1 for 619 segments (86.7%), the average motion score for all segments in an individual patient was 1.14 (range, 1-3.35), and the average opacification score for all segments in a patient was 1.02 (range, 1-1.38). A total of 374 segments were less than 2 mm in diameter. Combining the scores for both reviewers, an average of 36 segments (5.0% of 714) could not be identified by the reviewers, 319.5 segments (85.4%) were well seen, and 18.5 segments (4.9%) were poorly seen. Overall, an average of 637 segments (89.2%) were judged assessable by the reviewers. On a per-patient basis, 10 or more vessel segments were judged assessable in 47 patients (94%). CONCLUSION: On 64-MDCT, 89% of coronary artery segments are assessable. Ten or more vessel segments are assessable in 94% of patients.

Adolescent↗
PubMed2006

Clinically significant abnormal findings on the "nondiagnostic" CT portion of low-amperage-CT attenuation-corrected myocardial perfusion SPECT/CT studies.

UNLABELLED: Attenuation correction is recommended to optimize the performance of cardiac SPECT. The 2.5-mA CT commonly used for this purpose in myocardial perfusion SPECT is generally considered "nondiagnostic" in quality. In other areas of cardiac and hybrid imaging, diagnostically relevant abnormal findings on higher-quality CT studies have been described. The purpose of this study was to establish the frequency and significance of abnormal findings on low-amperage-CT cardiac SPECT/CT scans and to assess whether a systematic review of the nondiagnostic CT findings should be recommended. METHODS: Two hundred consecutive patients who underwent clinical low-amperage-CT attenuation-corrected myocardial perfusion studies acquired on a SPECT/CT system were included in the study. The cardiac CT images were reviewed in consensus by both an experienced CT reader and a nuclear medicine resident less experienced in CT. Abnormal CT findings of varying significance were recorded. RESULTS: Eighty-one patients had no abnormal CT findings. In the remaining 119 patients, 234 abnormalities were detected. Twenty-five major findings (in 21 patients) were seen, and 16 of these had been previously unrecognized. Sixty-four minor and 131 minimal findings were noted. Fourteen findings were labeled as equivocal (i.e., the CT findings were not definite). CONCLUSION: Potentially significant abnormal findings on the nondiagnostic-CT portion of the cardiac SPECT/CT examination were detected in 10.5% of our patients. These data suggest that, in addition to the review of the emission image dataset, low-amperage-CT findings should routinely be assessed for major diagnostic abnormalities.

Adolescent↗
PubMed2005

Combined PET/CT for detecting recurrent ovarian cancer limited to retroperitoneal lymph nodes.

OBJECTIVE: To evaluate the utility of combined positron emission tomography/computed tomography (PET/CT) for detecting recurrent epithelial ovarian cancer limited to retroperitoneal adenopathy. METHODS: Fourteen patients (median age = 53 years) with rising serum CA125 levels, and negative or equivocal conventional CT imaging > or = 6 months after primary therapy were retrospectively identified as having recurrent disease limited to retroperitoneal lymph nodes by combined PET/CT and underwent surgical reassessment of targeted nodal basins. Fisher's Exact Test was used to measure the ability of PET/CT to predict isolated retroperitoneal nodal disease. RESULTS: The median increase in serum CA125 from baseline nadir was 14 U/ml (range = 2-76 U/ml). There were 29 target nodes in 15 nodal basins identified with increased metabolic uptake on combined PET/CT. Eleven patients (78.6%) had recurrent ovarian cancer in retroperitoneal lymph nodes targeted by PET/CT. Of 143 nodes retrieved, 59 contained recurrent ovarian cancer (median nodal diameter = 2.5 cm, range = 0.8-5.2 cm). For all target nodal basins, the sensitivity, specificity, positive and negative predictive values, and accuracy for recurrent ovarian cancer in dissected lymph nodes were: 40.7% (24/59), 94.0% (79/84), 82.8% (24/29), 69.3% (79/114), and 72.0% (103/143) (P < 0.001). PET/CT failed to identify microscopic disease in 59.3% of pathologically positive nodes. CONCLUSION: Combined PET/CT demonstrates high positive predictive value in identifying recurrent ovarian cancer in retroperitoneal lymph nodes when conventional CT findings are negative or equivocal. The high incidence of occult disease within the target nodal basins suggests that regional lymphadenectomy may be necessary for complete secondary cytoreduction of recurrent disease.

Adult↗
PubMed2005

Optimal contrast agents for vascular imaging on computed tomography: iodixanol versus iohexol.

RATIONALE AND OBJECTIVES: Dimeric nonionic iodinated contrast has a lower osmolality than monomeric nonionic iodinated contrast but is available at lower iodine concentrations. Less dilution of intravascular fluid by influx from the extravascular space is proposed to occur with decreasing osmolality. The purpose of this study was to determine if a dimeric nonionic iso-osmolar contrast agent (iodixanol) gives equal vascular enhancement compared with a monomeric nonionic hyperosmolar contrast agent (iohexol). MATERIALS AND METHODS: A dynamic single-level computed tomography (CT) scan was performed of the abdominal aorta of 12 sedated rabbits using a four-row multidetector CT scanner following injection of 1.5 mL contrast/kg body weight at 2 mL/sec. The rabbits were injected with the dimeric contrast agent iodixanol (Visipaque 320; Amersham Health) or the monomeric contrast agent iohexol (Omnipaque 350; Amersham Health). The order of the type of contrast media injected was randomized for each rabbit, and the interval between injections was 2 weeks. Using the 2.5-mm detectors, four contiguous 3-mm contrast-enhanced scans were obtained at a single level every 5 seconds for 120 seconds (total of 24 scans) with a kVp of 120, mA.s of 110, field of view of 106 mm, and soft tissue reconstruction algorithm. A single level was chosen to measure the attenuation of the abdominal aorta at 5-second intervals. The mean attenuation and standard deviation values were recorded for the whole aorta, for the central half of the vessel, and for the peripheral half of the vessel. A log-log transformation of the data was performed and regression analysis was done on the outcomes of interest (e.g., mean, standard deviation) on time for each region. RESULTS: There was no statistically significant difference in mean attenuation for the whole aorta for iodixanol and iohexol (P = .918) even though the iodine content was 9.3% less with the dimeric iodixanol. The time-attenuation curve of iodixanol paralleled that of iohexol for all time points. The mean attenuation values of the central half of the aorta (P = .354) and peripheral half of the aorta (P = .758) were also not statistically different for the two contrast agents. CONCLUSION: The vascular attenuation provided by a 9.3% lower iodine concentration of iso-osmolar iodixanol is equal to that given by hyperosmolar iohexol. This suggests that there is less intravascular dilution of iso-osmolar contrast. The enhancement across the cross section of the vessel is also similar for both contrast agents. This suggests the vascular studies with iodixanol and iohexol are of equal quality even when a lower dose of iodine is given with iodixanol. It is relevant for patients with borderline or diminished renal function in whom less volume of contrast may be administered.

Animals↗
PubMed2005

Anatomic relationship between the vaginal apex and the bony architecture of the pelvis: a magnetic resonance imaging evaluation.

OBJECTIVE: This study was undertaken to define anatomic relationships between the vaginal apex and the ischial spines and sacrum for nulliparous women with normal support. STUDY DESIGN: We retrospectively evaluated the magnetic resonance images of 11 consecutive women who underwent pelvic imaging at Johns Hopkins. Coordinates were recorded for the posterior fornix, sacrum, ischial spines, and cervical vaginal junctions. We calculated vector distances with means, SDs, and 95% CIs. Intraclass correlation coefficients tested interobserver reliability and the Wilcoxon signed rank test compared right- and left-sided measurements. RESULTS: Mean age was 30.4 +/- 9.1 years. The cervical vaginal junction was 1.6 +/- 0.5 cm superior, 1.1 +/- 0.5 cm anterior, and 4.7 +/- 0.4 cm medial to the ipsilateral ischial spine. The posterior fornix was 1.0 +/- 1.0 cm anterior and 5.3 +/- 0.8 cm inferior to the second sacral vertebra. There was excellent interobserver reliability (interclass correlation coefficients = 0.997, P < .001) and no detectable difference between sides. CONCLUSION: Consistent relationships exist between the vaginal apex and ischial spines and sacrum, which may be useful in reconstructive pelvic surgery.

Adult↗
PubMed2005

MDCT evaluation of the coronary arteries, 2004: how we do it--data acquisition, postprocessing, display, and interpretation.

OBJECTIVE: Cardiac CT is rapidly becoming part of clinical practice. The objective of this article is to discuss and illustrate the current practice of coronary artery MDCT, including data acquisition, postprocessing, image display, and interpretation. The practice described reflects our experience with a series of patients referred in routine clinical practice. CONCLUSION: The reader should gain an insight into the current clinical application of coronary artery CT.

Contrast Media↗
PubMed2004

Perineal descent and levator ani hernia: a dynamic magnetic resonance imaging study.

PURPOSE: Patients with symptomatic pelvic organ prolapse often have multifocal pelvic floor defects that are not always evident of physical examination. In this study, dynamic magnetic resonance imaging of symptomatic patients with pelvic floor prolapse demonstrated unsuspected levator ani hernia. This study was designed to identify any specific symptoms and/or physical findings associated with these hernias. METHODS: Eighty consecutive patients with pelvic organ prolapse, fecal and/or urinary incontinence, or chronic constipation received standardized questionnaires, physical examination, and dynamic magnetic resonance imaging. Fisher's exact test was used to compare symptoms and examination findings between patients with or without levator ani hernia. RESULTS: Twelve patients (15 percent) were found to have unilateral (n = 8) or bilateral (n = 4) levator ani hernias on dynamic magnetic resonance imaging. No one specific symptom was directly associated with the presence of a levator ani hernia. Furthermore, levator ani hernias were not found more frequently in patients with previous pelvic floor surgery. Perineal descent on physical examination was associated with the finding of a levator ani hernia in nine patients (P = 0.02). Although not statistically significant, there was a trend toward a lower incidence of levator ani hernia in females using estrogen replacement therapy (P = 0.06). CONCLUSIONS: Patients with symptomatic pelvic organ prolapse and perineal descent on physical examination may have a levator ani hernia. Although the significance of levator ani hernia needs to be determined, the recurrence rate after the surgical management of pelvic organ prolapse remains unacceptably high, and ongoing investigation of all associated abnormalities is warranted.

Adult↗
PubMed2004

3-dimensional magnetic resonance imaging modeling of the pelvic floor musculature in classic bladder exstrophy before pelvic osteotomy.

PURPOSE: We provide a 3-dimensional (3D) model of the pelvic floor musculature in patients with classic bladder exstrophy using magnetic resonance imaging (MRI). MATERIALS AND METHODS: Five male infants 1 day to 12 months old underwent MRI of the pelvis, which was compared to pelvic MRI of 1 male infant without pelvic floor abnormalities. Of the patients 3 were studied before primary closure and 2 before reclosure. None of the patients had a prior pelvic osteotomy. While the entire pelvic floor was imaged, special attention was paid to the contours of the levator ani muscle group which were drawn on T1-weighted axial and coronal images. The overlap of contours in these 2 planes was used to construct a 3D model of this muscle group. The diastasis of the pubic symphysis was also measured for all patients on a plain pelvic radiograph. RESULTS: The levator ani muscle group conformed to an elliptical dome shape in the control. For the patients the 3D shape was somewhat irregular with an apparent kink in the ellipse. The elliptical shape of the group was described by a shape factor, s, which equals the ratio of the maximum height-to-the length of the base of the ellipse. The shape factor was equal to 0.176 in the control compared to a mean of 0.448 for the patients. There was no relationship between diastasis of the pubic symphysis and the extent of disproportionate curvature of the levator group. CONCLUSIONS: To our knowledge this is the first qualitative description of the pelvic floor anatomy in bladder exstrophy using MRI. Our model gives further insights into the true pelvic floor anatomy in exstrophy cases and is the first to suggest that abnormalities in the pelvic floor may not correlate with abnormalities of the bony pelvis.

Bladder Exstrophy↗
PubMed2003

Computer-assisted detection of pulmonary nodules: preliminary observations using a prototype system with multidetector-row CT data sets.

The continued revolution in multidetector-row CT (MDCT) scanning increases the quality of lung imaging but at the cost of a greater burden of data for review and interpretation. This article discusses our preliminary experience with prototype software for lung nodule detection and characterization using MDCT data sets. We discuss the potential role of computer-assisted detection (CAD) as applied to the automatic detection of lung nodules. We also review the process of CAD, outline its potential results, and explore how it may fit into existing radiology practice. Finally, we discuss MDCT data-acquisition parameters and how they may affect the performance of CAD.

Algorithms↗
PubMed2003

Evaluation of cervical cancer by computed tomography: current status.

In the evaluation of cervical cancer, computed tomography (CT) is used primarily to stage advanced tumors and evaluate for recurrence. Because of reports that CT imaging lacks sensitivity and specificity in the detection of primary tumors and metastatic lesions, its use in these applications has been limited, but recent improvements in CT technology may have increased its accuracy and may broaden its use. At the Second International Conference on Cervical Cancer, held April 11-14, 2002, the limitations of single-detector row CT scanners were compared with the capabilities of new CT technology. Improvements include the introduction of multidetector-row CT scanners, which can produce thinner tissue slices. This technology is needed for detection of parametrial extension, pelvic side-wall disease, extension into the pelvic viscera, lymphadenopathy, local tumor recurrence, and distant metastatic disease. New technology reduces the thickness of each slice to 1-3 mm, improving spatial resolution and making multiplanar imaging possible, which previously was feasible only with magnetic resonance imaging. Studies are needed to assess the use of the improved CT technology in evaluating cervical cancer.

Female↗
PubMed2003

Architectural differences in the bony pelvis of women with and without pelvic floor disorders.

OBJECTIVE: To investigate the hypothesis that the architecture of the bony pelvis differs between women with and without pelvic floor disorders. METHODS: We designed a case-control study of women who had undergone magnetic resonance imaging (MRI) of the pelvis at our institution. Records were reviewed to identify women with and without pelvic floor disorders (urinary or anal incontinence, other symptoms of urinary tract dysfunction, or pelvic organ prolapse). Pelvimetry techniques were standardized. Relevant measures included transverse diameter of the inlet, angle of the pubic arch, intertuberous diameter, interspinous diameter, sacrococcygeal length, depth of sacral curvature, anteroposterior conjugate, obstetrical conjugate, and anteroposterior outlet. Multiple logistic regression analysis was used to identify women with pelvic floor disorders as a function of their pelvic dimensions, controlling for potentially confounding variables. RESULTS: Subjects included 59 women with pelvic floor disorders and 39 women without pelvic floor disorders. Women with pelvic floor disorders had a wider transverse inlet, wider intertuberous diameter, wider interspinous diameter, greater sacrococcygeal length, deeper sacral curvature, and narrower anteroposterior outlet. When controlling for the confounding effects of age, race, and parity, we found that a wider transverse inlet (odds ratio 3.425) and a shorter obstetrical conjugate (odds ratio 0.233) were significantly associated with pelvic floor disorders. CONCLUSION: A wide transverse inlet and narrow obstetrical conjugate are associated with pelvic floor disorders. We speculate that these features of bony pelvic architecture may predispose the patient to neuromuscular and connective tissue injuries, leading to the development of pelvic floor disorders.

Adult↗
PubMed2003

Dynamic MR imaging of female organ prolapse.

MR imaging is a viable technique for evaluating pelvic organ prolapse. Dynamic imaging with adequate increase in abdominal pressure is necessary for a successful study. Rectal contrast for patient defecation is easy to administer and also allows for the diagnosis of rectal abnormalities. Additional work is needed on the soft tissue changes of prolapse and grading criteria for MR.

Female↗
PubMed2003

Clinically occult recurrent ovarian cancer: patient selection for secondary cytoreductive surgery using combined PET/CT.

OBJECTIVE: The aim of this study was to evaluate the utility of combined positron emission tomography/computed tomography (PET/CT) for identifying ovarian cancer tumor masses > or =1 cm in patients with clinically occult recurrent disease by conventional CT imaging. METHODS: Twenty-two patients with epithelial ovarian cancer, rising serum CA125 levels, and negative or equivocal conventional CT imaging > or =6 months after primary therapy underwent combined PET/CT imaging followed by surgical reassessment. Fisher's exact test was used to measure the ability of PET/CT to predict macroscopic disease > or =1 cm. RESULTS: The median patient age was 55 years, and 91% of patients had FIGO Stage IIIC/IV disease. The median increase in serum CA125 was 24 U/ml (range 10 to 330 U/ml). Conventional CT was reported as negative (n = 15) or equivocal (n = 7) in all cases. Eighteen patients were ultimately found to harbor recurrent ovarian cancer measuring > or =1 cm at the time of surgery, with a median maximal tumor diameter of 2.3 cm (range 1.5 to 3.2 cm). The overall patient-based accuracy of PET/CT in detecting recurrent disease > or =1 cm was 81.8%, with a sensitivity of 83.3% and positive predictive value of 93.8% (P = 0.046). Of patients with recurrent ovarian cancer > or =1 cm, complete cytoreduction to no gross residual tumor was accomplished in 72.2%. CONCLUSION: PET/CT imaging demonstrates high sensitivity and positive predictive value in identifying potentially resectable, macroscopic recurrent ovarian cancer among patients with biochemical evidence of recurrence and negative or equivocal conventional CT findings. In appropriately selected patients, early identification of macroscopic recurrent disease may facilitate complete surgical cytoreduction.

CA-125 Antigen↗
PubMed2003

Current concepts in multi-detector row CT evaluation of the coronary arteries: principles, techniques, and anatomy.

Cardiac imaging is becoming a practical application of mechanical computed tomography (CT) with the availability of four, eight, and 16 detector row scanners. The role of imaging is progressing from simple determination of the presence of arterial calcifications on nonenhanced scans to demonstration of vascular stenoses on coronary CT angiograms. Optimization of the imaging technique and knowledge of coronary artery anatomy are both important for the development of CT of the heart. Technical factors such as a slow heart rate, a short scanning time, subcentimeter spatial resolution, high temporal resolution, and reconstruction of multiple image data sets at various intervals in the cardiac cycle result in optimal visualization of the coronary arteries. Axial, thin-slab maximum intensity projection, and volume-rendered images are used to display the normal anatomy and anomalies of the coronary arteries. The challenges of CT angiography of the coronary arteries have been partially met and will likely be overcome with continued evolution of the technology.

Artifacts↗
PubMed2003

Uptake in supraclavicular area fat ("USA-Fat"): description on 18F-FDG PET/CT.

UNLABELLED: The supraclavicular region is a common site for lymph node metastases. A commonly reported type of nonmalignant (18)F-FDG uptake on PET imaging in the supraclavicular region is "muscle uptake" purportedly due to muscle contraction in tense patients during the (18)F-FDG uptake phase. PET/CT offers the unique opportunity to correlate PET findings with CT anatomy in the supraclavicular region. METHODS: Images from the first 359 consecutive clinical whole-body studies (in 347 patients) using (18)F-FDG and a PET/CT scanner (with CT attenuation correction and ordered-subsets expectation maximization [OSEM] reconstruction) were retrospectively reviewed. The supraclavicular region was evaluated for the presence of abnormal uptake on PET images, and the corresponding CT findings were assessed. Three distinct patterns of abnormal (18)F-FDG uptake were noted: pattern A (uptake localizing to supraclavicular area fat [USA-fat], i.e., without corresponding lymph node or muscle uptake on CT), pattern B (uptake localizing to muscle on CT), and pattern C (uptake localizing to lymph nodes or soft-tissue masses on CT). RESULTS: Forty-nine patients (14.1%) (32 female, 17 male; mean age, 51.4 +/- 15.6 y; age range, 12-77 y) showed abnormal (18)F-FDG uptake in the supraclavicular region. Twenty patients (5.8%) had muscle uptake (group B); 15 (4.3%) had definite abnormal lymph nodes (group C). However, 14 patients (4.0%) had USA-fat (group A) and foci of very low Hounsfield units on CT. These foci were also present on (68)Ge attenuation-corrected images (when obtained) and non-attenuation-corrected images. Uptake in USA-fat was typically bilateral and symmetric, intense, more often multifocal than linear, and located in fat on PET/CT. Age was not significantly different for group C versus the 2 other groups. Intensity; mean standardized uptake value, lean (SUV(L MEAN)); or maximum standardized uptake value, lean (SUV(L MAX)), did not allow differentiation between patterns A and C (P > 0.05). Standardized uptake values (SUV(L MAX), 3.1; SUV(L MEAN), 2.1) were significantly lower in group B than in the 2 other groups (P < 0.005). CONCLUSION: So-called muscle uptake in the supraclavicular region may be caused in a significant proportion of cases by an unrelated process we call the USA-fat finding, with (18)F-FDG uptake in tissues of low-Hounsfield (fat) density. This finding most likely reflects an underlying nonpathologic process that we hypothesize to be in foci of brown fat. This intense supraclavicular uptake should be recognized and should not be misinterpreted as a malignant metastatic process or as muscle uptake.

Adipose Tissue↗