A low-cost, full-function picture archiving and communication system using standard PC hardware and the traditional 4-over-4 display format.

OBJECTIVE: With a 12-year background of our completely digital nuclear medicine picture archiving and communication system (PACS), we have recently implemented a novel PACS, OpenPACS, which can be used for interpretation and display of CT, MR imaging, sonography, nuclear medicine, and computed and digital radiography studies. OpenPACS uses low-cost standard PC hardware and software that is widely available and is readily serviced and maintained. The OpenPACS application program is available over the Internet. CT or MR imaging slices from one or multiple studies can be presented simultaneously or in cine mode on a wall-sized multimonitor display. The assembly, with a total resolution of 6400 x 4800 pixels, resembles a traditional array of eight standard X-ray viewboxes. A wireless mouse is used to vary attenuation and other display parameters. Multiple backup and redundancy are provided. Currently, six CT and six MR imaging scanners of different vendors are networked to OpenPACS, which is also networked to our nuclear medicine PACS. CONCLUSION: After only a brief introduction, radiologists rapidly become familiar with the system because it is based on the use of standard Windows icons and procedures and offers a display that resembles a standard X-ray film presentation.

Multiplanar CT pancreatography and distal cholangiography with minimum intensity projections.

PURPOSE: To develop a technique of projectional computed tomographic (CT) cholangiopancreatography (CTCP). MATERIALS AND METHODS: Sixty-one patients underwent CT for suspected biliary or pancreatic abnormalities. The axial CT and CTCP techniques included spiral scanning during the portal venous phase and thick-slab minimum intensity projections. Visualization of pancreatic and extrahepatic bile ducts (divided in five duct segments per patient) was graded blindly on a scale of 1-5 by a consensus of two radiologists. Two hundred seventy-seven duct segments were used to compare axial CT and CTCP in the depiction of duct segments and dilatation; 109 segments were used to compare CTCP with ERCP. RESULTS: Fifty-six of 277 duct segments were not visualized on axial CT images; 15 segments were not visualized on CTCP images (P < .001). There was no statistically significant difference between the number of segments missed with ERCP and the number missed with CTCP: nine and three of 109 segments, respectively. Duct visualization was equal on axial CT and CTCP images in 35 of 109 duct segments and was superior on CTCP images in all but one of the remaining segments (P < .001). Duct visualization on CTCP images was equal to that on ERCP images in 35 segments, superior in nine, and significantly inferior in 66 (P < .001). CONCLUSION: CTCP improves CT depiction of pancreatic and bile ducts with a quality that approaches that of ERCP.

Rectal tumor stage: correlation of endorectal MR imaging and pathologic findings.

PURPOSE: To develop magnetic resonance (MR) imaging criteria for staging rectal cancer. MATERIALS AND METHODS: Thirty-six patients with rectal tumors underwent MR imaging with an endorectal surface coil. MR images were compared with specimens from the resected tumor. RESULTS: Rectal wall layers were reliably demonstrated. The MR imaging-determined tumor stage agreed with pathologic findings in 81% of cases. A retrospective review found the integrity of the rectal wall layers at the lesion center an accurate criterion for interpreting the local extent of the lesion. Lymph nodes as small as 2 mm were demonstrated. Although sensitive for demonstrating perirectal adenopathy, MR imaging had a specificity of only 72% for N1 disease. CONCLUSION: Endorectal surface coil MR imaging shows promise for staging rectal lesions. Additional studies are necessary to further establish criteria for interpreting the images.

MR imaging with spatial modulation of magnetization in the evaluation of chronic central pulmonary thromboemboli.

PURPOSE: To assess the diagnostic value of magnetic resonance (MR) imaging with SPAMM (spatial modulation of magnetization) in the identification of chronic central pulmonary thromboemboli. MATERIALS AND METHODS: Twelve patients with pulmonary hypertension and five healthy volunteers were prospectively studied with a 1.5-T MR imaging system. The SPAMM technique was integrated into a conventional cardiac-synchronized spin-echo (SE) sequence. Six of the 12 patients had central thromboemboli. RESULTS: In the healthy subjects, intravascular stripes in the central pulmonary arteries disappeared as a result of flow within 100 msec after the R wave. Areas of persistent stripes were identified in seven of eight central pulmonary arteries with thromboemboli. Conversely, in the 16 central pulmonary arteries without clot, intraluminal stripes disappeared despite the presence of flow-related signal (sensitivity = 88%, specificity = 100%, accuracy = 96%). CONCLUSION: SPAMM appears to be a simple and effective technique for differentiating central pulmonary arterial thromboemboli from flow-related signal frequently observed with pulmonary hypertension.

Magnetic resonance imaging in cervical carcinoma: diagnosis, staging, and follow-up.

Clinicians have long looked for an imaging modality that can provide accurate and useful information on cervical carcinoma. In the past 10 years, magnetic resonance imaging (MRI) has come to play an important role in evaluating patients with this disease before treatment and in monitoring them afterward. Before treatment, MRI can accurately depict tumor size (volume) and extension. MRI thus has the potential to supplant the traditional clinical International Federation of Gynecology and Obstetrics (FIGO) staging system for this disease, which is based on clinical findings and is inherently subjective. Promising areas of research include endorectal, endovaginal, and phased-array coils.

Hepatic abscesses: MR imaging findings.

PURPOSE: To determine magnetic resonance (MR) imaging features that characterize hepatic abscesses. MATERIALS AND METHODS: Clinical records and MR studies of 18 patients with proved hepatic abscesses were evaluated. The abscesses were pyogenic in 15 patients, fungal in two patients, and amebic in one patient. RESULTS: A total of 122 lesions were identified. Most were round (n = 114) with sharp borders (n = 99), hypointense on T1-weighted images (n = 73), and very hyperintense on T2-weighted images (n = 88). After injection of gadopentetate dimeglumine in 43 lesions, all 43 enhanced with sharp margins and 37 showed rim enhancement. All abscesses followed up diminished in size (50 of 50), and perilesional edema resolved before the central cavity did. CONCLUSION: MR imaging findings seen in hepatic abscesses include high signal intensity on T2-weighted images (72%) and perilesional edema (43 of 122 [35%]). Rim enhancement (86%) and increased conspicuity (35 of 43 [81%]) were found after injection of gadopentetate dimeglumine.

The effect of dietary protein depletion on hepatic 5-fluorouracil metabolism.

BACKGROUND: Protein calorie malnutrition, which is highly prevalent in tumor-bearing hosts, increases toxicity to 5-fluorouracil (5-FU), but the mechanisms are unclear. This study investigated the effects of protein depletion on 5-FU in vivo hepatic metabolism using F19-nuclear magnetic resonance spectroscopy (19F-NMRS). METHODS: Rats received normal (21.5%) or low (2.5%) protein diet for 25 days. 5-FU was injected intraperitoneally, and hepatic fluorine spectra were obtained. Parallel experiments were conducted to determine serum 5-FU pharmacokinetics using high-performance liquid chromatography (HPLC) and to measure hepatic dihydropyrimidine dehydrogenase (DPD) activity. RESULTS: The mean time of initial detection of fluoro-beta-alanine and the mean duration of the 5-FU signal in the liver were significantly prolonged in the low-protein group. 5-FU clearance and hepatic DPD activity were significantly lower in the low-protein group. Low-protein animals demonstrated increased toxicity, with diarrhea, weight loss, leukopenia (P < 0.001), and an 85% mortality, compared with regular diet animals, who had mild diarrhea and weight loss but no leukopenia and a 12% mortality. CONCLUSION: Protein depletion results in increased toxicity to 5-FU, which is associated with a significantly decreased rate of hepatic metabolism and clearance of 5-FU and a significant decrease in hepatic DPD activity. 19F-NMRS can noninvasively identify these alterations of 5-FU metabolism in vivo and may serve as a useful guide to determining chemotherapy dosage adjustments to reduce toxicity.

Current role of MR imaging in the staging of adenocarcinoma of the prostate.

Surgical cure of adenocarcinoma of the prostate (ACP) is possible in over 80% of cases when the disease is confined to the gland capsule. The endorectal probe for magnetic resonance (MR) imaging has increased resolution of the prostate gland and capsule, which has improved the sensitivity and specificity for staging ACP (.65 sensitivity, .69 specificity for body coil; .87 sensitivity, .85 specificity for the endorectal coil). Normal glandular regions in the peripheral zone and central zone have significantly higher citrate levels than ACP and fibromuscular and fibrous benign prostatic hyperplasia at proton spectroscopy. ACP has a higher phosphomonoester-phosphocreatine ratio than normal glandular tissue at phosphorus spectroscopy. The combination of endorectal coil MR imaging for local spread, and body coil MR imaging for advanced disease, makes MR imaging the premier imaging modality for the preoperative staging of ACP.

First principles of fast spin echo.

Fast spin echo (FSE), a variant of the rapid acquisition with refocused echoes pulse sequence, is now being widely considered as an alternative to conventional spin echo for proton density and T2-weighted imaging. Although the medical experience with this sequence is relatively limited, relevant aspects of the technique have been well understood in the context of spectroscopic applications for many years. This article attempts to portray the subject in an appropriate historical context. Such a viewpoint promotes a deeper understanding of the artifacts, determinants of contrast, and future evolution of FSE. Hopefully, this may not only be of benefit in the design of optimal clinical imaging protocols for current state of the art but may also be of use in fashioning the criteria by which new developments in this field may be judged.

Magnetic resonance angiography of the pelvis and lower extremities. Works in progress.

Two-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) of the lower extremities has recently been rediscovered as a technique that can be used to find small vessels in the foot and leg for surgical revascularization in patients with severe peripheral vascular disease. The purpose of this article is to acquaint the reader with some of the common problems that may be encountered in this imaging technique and to show their derivations and solutions were applicable. In addition, the authors show receiver operator curve analysis of one radiologist's ability to determine the location and patency of arteries using this technique to be outstanding (AZ, 0.9737). This represents a promising new technique for imaging the arterial system in patients with severe peripheral vascular disease.

Evaluation of soft palate function with MRI: application to the cleft palate patient.

Magnetic resonance imaging was employed to evaluate soft palate function in four normal volunteers and four patients with surgically repaired cleft palate, using a GE Signa clinical scanner at 1.5 T and a custom designed receive coil with a sensitivity profile encompassing from the nasopharynx to the larynx. Midsagittal images were obtained using spoiled gradient recalled acquisition at steady state while the subject phonated the following sounds: (a) MMM, (b) SSS, (c) DAH, and (d) EEE. An image at rest with normal breathing was also obtained. The soft palate and its relationship to the airway and the posterior pharyngeal wall were clearly visualized in all cases. Phonation of the prescribed sounds demonstrated the normal range of soft palate motion. The images also depicted the ability of the soft palate to divert airflow to the nasopharynx. Interpretation of functional MRI may be of value in evaluation of surgical results, guidance of speech therapy, and surgical planning in the cleft palate patient. This noninvasive alternative to conventional methods of visualization provides advantages in resolution, repeatability, and patient comfort.

Mucinous carcinomas involving the prostate: atypical findings at MR imaging.

The magnetic resonance (MR) imaging findings in four patients with mucinous tumors involving the prostate are presented. The MR appearance of these tumors differed from that of typical prostatic adenocarcinomas in that the signal intensity on T2-weighted images approximated or exceeded that of the uninvolved peripheral zone. The unusual appearance of mucinous prostate tumors may present problems in diagnosis and staging with MR imaging.

The seminal tract in patients with ejaculatory dysfunction: MR imaging with an endorectal surface coil.

Twenty-six patients with signs and symptoms of ejaculatory dysfunction (hemospermia, hypospermia, oligospermia, or painful ejaculation) were examined with high-resolution MR imaging with an endorectal surface coil. Findings were abnormal in 15 patients. Abnormalities detected included four cases of müllerian cysts, three cases of wolffian cysts, one case of anaplastic prostatic carcinoma, and various noncystic abnormalities of the seminal vesicles and ejaculatory ducts, including ejaculatory duct obstruction and seminal vesiculitis. In all cases, depiction of both the normal and abnormal anatomy of the entire seminal tract, including the vas deferens, seminal vesicles, and ejaculatory ducts, was excellent. This depiction of the detailed anatomy of the prostatic cysts made it possible to suggest specific diagnoses. Our results show the value of MR imaging with an endorectal surface coil in the examination of patients with ejaculatory dysfunction.

Human exposure to 4.0-Tesla magnetic fields in a whole-body scanner.

Details are given for the design, construction, properties, and performance of a large, highly homogeneous magnet designed to permit whole-body magnetic resonance imaging and spectroscopy at 4 T. The magnet has an inductance of 1289 H and a stored energy of 33.4 MJ at rated field. The health of a group of 11 volunteers who had varying degrees of exposure to this field was followed over a 12-month period and no change that could be associated with this exposure was detected. A mild level of sensory experiences, apparently associated with motion within the field of the magnet, was reported by some of the volunteers during some of their exposures. A questionnaire regarding sensory effects associated with magnetic resonance scanners and possibly caused by the static magnetic field of these instruments, was given to nine respondents who had experience within both 1.5-T scanners and this 4-T scanner and to another group of 24 respondents who had experience only within 1.5-T scanners. For the sensations of vertigo, nausea, and metallic taste there was statistically significant (p less than 0.05) evidence for a field-dependent effect that was greater at 4 T. In addition, there was evidence for motion-induced magnetophosphenes caused by motion of the eyes within the static field. These results indicate the practicality of experimental whole-body body scanners operating at 4 T and the possibility of mild sensory effects in humans associated with motion within a static magnetic field. The results also indicate the likelihood of a wide margin of safety for the exposure of noncompromised patients to the static fields of conventional magnetic resonance scanners operated at 1.5 to 2 T and below.

Evaluation of gynecologic malignancy by magnetic resonance imaging.

Currently, MR imaging has demonstrated the greatest accuracy and has potentially the greatest clinical utility for the staging of cervical carcinoma. Endometrial carcinoma also can be staged by MR imaging with reasonable accuracy, although the clinical indications for preoperative endometrial carcinoma staging are less clear. MR imaging has unparalleled capacity for the tissue characterization of adnexal disease and has demonstrated utility for diagnosis of common adnexal masses such as pedunculated leiomyoma, endometrioma, and ovarian dermoid. Its use in the evaluation or staging of ovarian, vaginal, and vulvar carcinoma has not been evaluated fully. MR imaging can demonstrate complications of radiation therapy and surgery and can distinguish most recurrent carcinomas from postradiation fibrosis. New techniques such as arrayed use of surface coils, endoluminal surface coils, fast spin-echo acquisitions, and contrast agents show promise for contributing to the already rapid pace of technologic advancement in the field of MR imaging of the female pelvis.

Magnetic resonance imaging of abscesses using lipid-coated iron oxide particles.

RATIONALE AND OBJECTIVES: The authors investigated whether iron oxide particles can be used as a magnetic resonance imaging (MRI) contrast agent to image abscesses in a two-stage experimental design. METHODS: Human buffy coat was incubated with iron oxide particles of different sizes and coatings. Smears of the incubation mixture were made on a glass slide and stained for iron. The percentage of iron oxide uptake was determined by counting 100 neutrophils and monocytes and scoring the number of cells that contain iron. Subcutaneous abscesses were created in the flanks of 18 Sprague-Dawley rats by injecting them with 0.1 mL of turpentine. Iron oxide was given intravenously, and the animals were imaged by MRI (1.5 T) 12 to 24 hours later. Different iron oxide coatings and doses were compared. RESULTS: The four different types of coating (constant fragment [Fc] of IgG, bovine serum albumin [BSA], lipid [Ferrosome], and dextran) had an uptake of 72% +/- 5.3%, 61% +/- 6.2%, 30.5% +/- 6.8%, and 5% +/- 2.5%, respectively. Comparison of two particle sizes (mean, 90 versus 35 nm) showed the large particles to have higher uptake (61% +/- 6.2%) compared with the small particles (6% +/- 1.8%) (P less than .001). Post-contrast imaging of the rats showed a hypointense ring around the abscess only in the animals injected with the lipid-coated agent. The effect was discernible within 12 hours after contrast injection and at a dose of 25 mumols iron/kg. Histologic sections showed phagocytic cells with iron granules in the periphery of the abscess. No hypointense ring on MRI or iron granules on histologic sections was seen around the abscess of the control animals or those injected with BSA-iron oxide or Fc-iron oxide. CONCLUSIONS: Lipid-coated iron oxide particles can be used to image abscesses by virtue of their phagocytosis into surrounding inflammatory cells. Positive uptake of these particles by human phagocytes in vitro suggests that similar results may be applicable in humans.

Pulmonary MR angiography utilizing phased-array surface coils.

Magnetic resonance angiography of the pulmonary vasculature was evaluated in 12 subjects using breath-hold gradient echo scans and surface coils at 1.5 T. Flow-compensated GRASS, spoiled GRASS (SPGR), and WARP-SPGR sequences were utilized. Comparisons were made among flip angles of 10-60 degrees, slice thicknesses of 3-10 mm, and body coil as well as Helmholtz pair and phased-array multiple coils. With 30-40 contiguous slices encompassing the lung, intrathoracic vasculature was segmented using a UNIX/X-windows based package dubbed VIDA. Three-dimensional anatomy was visualized by a brightest voxel projection algorithm, following reduction of chest wall pixel intensities by an operator-interactive module. Both SPGR (30 degrees flip angle, 4 mm slice thickness) and WARPSPGR (15 degrees flip angle, 5 mm slice thickness) in combination with phased-array multiple coils provided the most satisfactory images, based upon observations by three radiologists and signal-to-noise ratio measurements. The MR angiograms visualized vessels as distal as sixth to seventh order branches. The technique was successfully applied to three patients with pulmonary embolism. The results of this study demonstrate that the pulmonary vascular tree can be imaged by MR angiography combining a high resolution technique utilizing phased-array multiple coils, fast gradient echo sequences with breath-holding, and postprocessing of the volumetric image data. The technique is attractive since it is noninvasive and provides a full three-dimensional portrayal of the pulmonary vasculature.

MR imaging of the pelvis with an endorectal-external multicoil array.

Magnetic resonance (MR) images of the pelvis obtained with an endorectal coil have improved resolution relative to that of body coil images; however, they have limited spatial coverage. The sensitivity profile can be improved by using the endorectal coil combined with an external anterior coil as part of a multicoil array. If each coil is connected to a separate receiver, the individual images can be combined to provide an optimal signal-to-noise ratio (S/N). The authors have investigated a 5-inch (12.7-cm) surface coil or a two-coil array as the anterior coil. In both of these configurations, the S/N is improved relative to that of the endorectal coil alone at distances greater than 3 cm from the endorectal coil. The anterior two-coil array provides more lateral coverage. The improved spatial coverage available with this technique expands potential clinical applications of endorectal MR imaging.