Prostate cancer and prostate bed SPECT imaging with ProstaScint: semiquantitative correlation with prostatic biopsy results.

BACKGROUND: ProstaScint (Cytogen Corporation, Princeton, NJ) murine monoclonal antibody imaging is FDA-approved for imaging of prostate cancer patients at high risk for metastatic disease and patients postprostatectomy with a rising serum prostate-specific antigen (PSA) level. ProstaScint is a murine monoclonal antibody which targets prostate-specific membrane antigen (PSMA). PSMA expression is upregulated in primary and metastatic prostate cancer. FDA Cytogen (Princeton, NJ) protocol studies using 111indium-labeled ProstaScint revealed correlation between areas of increased concentration in the prostate and biopsy-proven tumors in patients imaged pretherapy. METHODS: In our study, four transverse, single-photon emission tomography (SPECT) images were isolated and regions of interest were selected and correlated with pretherapy prostate biopsy results. Prostate cancer and normal tissue prostate/muscle background (P/M) ratios were derived, so that postprostatectomy/radiation therapy patients could be evaluated for the presence of residual prostate cancer. Twenty-three pretherapy prostate cancer patients with quadrant/sextant biopsies had SPECT 96-hr 111indium ProstaScint pelvic images. The four transverse 1-cm slices above the midline penile blood pool were chosen, and four to six 27-30-pixel regions of interest were placed over the prostate bed. The background muscle region of interest was placed over the external obturator muscle region. The P/M ratio was calculated and compared to the quadrant/sextant prostatic biopsy result. The same procedure was applied to 17 posttherapy prostate cancer patients with rising PSA. RESULTS: In the 23 pretherapy prostate cancer patients, there was a correlation between the P/M ratio of at least 3.0 in 32 of 35 prostatic cancer biopsy regions, and there was correlation with P/M ratios less than 3.0 in 82 of 89 negative biopsy regions. Seventeen posttherapy patients underwent ProstaScint studies. Six underwent biopsy, with typically one biopsy site per patient. All 6 had P/M ratios greater than 3.0 in the biopsied region. Five out of six biopsies revealed residual prostate cancer. CONCLUSIONS: A prostate/muscle ratio was developed from 111indium ProstaScint regions of interest obtained on 1-cm SPECT transverse slices through the prostate bed in 23 patients preprostatic cancer therapy. A P/M ratio above 3.0 correlated in the majority of positive cases, and a P/M ratio below 3.0 was demonstrated in negative prostatic biopsy cases. The P/M ratio of above 3.0 or below 3.0 also separated those posttherapy prostate cancer patients with rising PSA who had residual prostate carcinoma in the prostate bed.

Preliminary imaging results using In-111 labeled CYT-356 (Prostascint) in the detection of recurrent prostate cancer.

To evaluate whether In-111 capromab pendetide (an antibody conjugate directed to a glycoprotein found primarily on the cell membrane of prostate tissue) radioimmunoscintigraphy can localize residual or metastatic prostatic carcinoma in 15 patients after prostatectomy and lymphadenectomy for prostatic carcinoma with rising serum prostate-specific antigen. One patient with 0.6 ng/ml serum prostate-specific antigen had normal imaging results and 14 patients had scintigraphic evidence of residual prostatic bed or metastatic prostatic carcinoma. Two patients with borderline abnormal bone scans had abnormal activity in the same regions on In-111 capromab pendetide images. All patients had negative radiographic abdominal and pelvic cross-sectional prestudy images, and there were no adverse effects related to In-111 capromab pendetide infusion and little human antimouse antibody response.

A geometric method of measuring the left ventricular ejection fraction on gated Tc-99m sestamibi myocardial imaging.

Geometric measurements of the left ventricular diameters as used in biplane angiocardiography and echocardiography were applied to gated SPECT Tc-99m sestamibi myocardial scintigrams in order to calculate the left ventricular ejection fraction. These measurements take no longer than 5 minutes and require no additional computer software. In a review of 79 examinations, the left ventricular ejection fraction calculated using these measurements correlated well with the echocardiographically estimated ejection fraction (r = 0.78, P < 0.0001). The technique is highly reproducible with an intraobserver correlation of r = 0.94 and interobserver correlation of r = 0.93.

Use of Tc-99m sestamibi infusion for detection of hibernating myocardium. A preliminary report.

To evaluate whether a prolonged infusion of Tc-99m sestamibi allows for visualization of viable myocardium in areas of hypoperfused myocardium, 25 patients were prospectively studied. Each patient was imaged four times in two consecutive days in the following manner: day 1:1) immediately after injection of Tl-201 at rest, 2) 1 hour after a bolus injection of Tc-99m sestamibi at rest; and day 2: 1) imaging in the Tl-201 window for 24 hour redistribution, 2) imaging after a 1-hour infusion of Tc-99m sestamibi. The two Tc-99m sestamibi and two Tl-201 studies were evaluated for presence of redistribution. This was present both on the Tl-201 and Tc-99m sestamibi studies (concordant) in 13 cases, and absent on both the Tl-201 and Tc-99m sestamibi studies (concordant) in 9 cases. In two cases redistribution was seen on the Tl-201 images only, and in one case it was seen on the Tc-99m sestamibi images only (discordant). Tc-99m sestamibi infusion may provide information about the presence of viable myocardium which is similar to that provided by Tl-201 24-hour imaging.

MR susceptometry: an external-phantom method for measuring bulk susceptibility from field-echo phase reconstruction maps.

A novel method for estimating the susceptibility of an object by using the magnetic resonance (MR) imaging field distortions in an external-reference water bath next to the object is described. The field measurement was obtained with a phase reconstruction from a gradient-echo acquisition. A field model of an arbitrary object in a static magnetic field was discretely calculated from geometry determined from the magnitude reconstruction. Least-squares estimation yields the susceptibility of the object. Required (and proven) assumptions include validity of superposition, object homogeneity, negligible higher-order field terms, field-model accuracy, geometric-model accuracy, and correlation of gradient-echo phase to field distortion. MR susceptometry estimation of phantoms yielded susceptibility estimates that correlated well with known values (r > .9975). This MR susceptometry method is a first step toward quantitation of iron levels through MR imaging phase information in patients with iron overload.

Use of magnetization transfer for improved contrast on gradient-echo MR images of the cervical spine.

PURPOSE: To evaluate whether magnetization transfer (MT) can improve image contrast on gradient-recalled echo (GRE) magnetic resonance (MR) images of the cervical spine. MATERIALS AND METHODS: Sagittal and axial two-dimensional conventional GRE and MT GRE images were obtained in 103 patients with degenerative disk disease or intrinsic cord lesions. The contrast-to-noise ratios (C/Ns) for the cervical spinal cord and cerebrospinal fluid (CSF) were compared for images obtained at various MT power level and section-select flip angle combinations. Axial three-dimensional GRE images were also obtained with application of MT and C/N evaluated in 10 additional patients. RESULTS: Tailored two-dimensional MT GRE images, obtained with a moderate MT power level and a section-select flip angle similar to the Ernst angle for CSF, provided an average of 2.2-2.4-fold improvement in spinal cord-CSF C/N than conventional GRE images (P < .001). CONCLUSION: The MT GRE images demonstrated superior delineation of disk herniations, foraminal stenosis, and intrinsic cord lesions over conventional GRE and T2-weighted spin-echo images in clinical cervical spine examinations.

Improved contrast of enhancing brain lesions on postgadolinium, T1-weighted spin-echo images with use of magnetization transfer.

PURPOSE: To prove that the contrast of enhancing brain lesions on post-gadolinium T1-weighted spin-echo (SE) images can be statistically significantly improved with magnetization-transfer (MT) indirect saturation. MATERIALS AND METHODS: The contrast-to-noise ratios (C/Ns) of 201 enhancing brain lesions in 110 patients were compared on conventional and MT T1-weighted SE images obtained at 1.5 T after injection of 0.05-0.10 mmol/kg gadopentetate dimeglumine or gadodiamide. RESULTS: The MT T1-weighted SE images showed a 37% reduction in signal intensity of background white matter and thereby provided a 108% improvement in the C/N of enhancing brain lesions over the conventional T1-weighted SE images (P < .001). CONCLUSION: The C/Ns obtained with single-dose gadolinium and the MT T1-weighted SE technique were twice those obtained with the conventional technique and are at least equivalent to reported values obtained with triple-dose gadolinium and conventional T1-weighted SE images.

MR imaging of the juvenile temporomandibular joint: preliminary report.

Thirty-two children were evaluated by means of medical history and physical examination for signs and symptoms of internal derangement (ID) of the temporomandibular joint (TMJ) and mandibular dysfunction. These children also underwent magnetic resonance (MR) imaging of the TMJs. The study was double blind. At clinical examination, 19 patients (59%) had at least one positive finding of ID of the TMJ and/or mandibular dysfunction. MR images of the TMJ obtained in 60 of the 64 TMJs demonstrated 57 normal joints (95%) and three abnormal joints (5%). Two of these three joints had a mild anterior-lateral disk displacement, and one joint had an anterior dislocated disk. There were no false-positive MR examinations. MR imaging failed to depict abnormalities in 16 patients who had positive findings at history and/or physical examination. Although MR imaging may fail to depict ID of the TMJ in some patients, clinical techniques commonly used in population surveys probably overstate the prevalence of ID of the TMJ in children.

Atypical appearance of lipomatous tumors on MR images: high signal intensity with fat-suppression STIR sequences.

Lipomatous tumors generally have signal characteristics that allow them to be diagnosed with great accuracy by means of magnetic resonance imaging. These tumors usually have signal intensities similar to those of subcutaneous fat on both T1- and T2-weighted spin-echo images. Previous reports have not, to the authors' knowledge, described the appearance of lipomatous tumors on images obtained with a short-inversion-time inversion-recovery (STIR) sequence, which can be used to suppress signal from fat. Three lipomatous tumors (two liposarcomas and one lipoma) with signal characteristics unlike those of normal subcutaneous fat at all pulse sequences are presented.

Incidental detection of urinary tract abnormalities with skeletal scintigraphy.

Urinary tract abnormalities are detected as incidental findings in 15% of skeletal scintigraphic studies. Several scintigraphic patterns denote these abnormalities. Bilateral diffuse increased uptake is found in patients who have undergone chemotherapy and those with hyperparathyroidism, hypercalcemia, and sickle cell disease. Bilateral diffuse decreased uptake occurs in patients with end-stage renal disease, extensive metastatic disease to the bone, and various hematologic disorders. Focal increased activity is associated with postoperative changes and effects from radiation therapy. Focal decreased uptake is caused by space-occupying lesions such as abscesses, cysts, and neoplasms. Abnormal size, shape, and position associated with abnormalities of the kidney and bladder can also be seen. Although these scintigraphic patterns are seldom suggestive of a definitive diagnosis, they are highly specific for urinary tract disease.

Generation of parametric images during routine Tc-99m PYP inhalation/Tc-99m MAA perfusion lung scintigraphy. Technical note.

A simple technique is described for generating ventilation/perfusion ratio and perfusion/ventilation ratio images from the posterior Tc-99m PYP aerosol inhalation and Tc-99m MAA perfusion images obtained during routine lung scintigraphy. These images highlight areas of ventilation/perfusion incongruence--mismatch or reverse mismatch--that may sometimes be difficult to detect on conventional images.

Diagnosis of ruptured intracranial dermoid cyst: value MR over CT.

The CT and MR findings of seven patients with pathologically proved ruptured dermoid cysts were reviewed to analyze the MR characteristics and to see if MR evaluation had significant advantages over CT. In six cases, both CT and MR identified fatty material in the CSF spaces. Hemorrhage complicated preoperative diagnosis in one case. Patterns of extraaxial fat distribution were as follows: intraventricular fat/CSF levels (three patients), generalized subarachnoid spread (six patients), and localized subarachnoid spread with sulcal widening (one patient). There was no correlation between fat distribution and clinical symptoms. MR showed the vascular involvement better than CT did in five of seven cases, and showed extension of the cysts into the skull base in two cases. Signal intensity of the solid mass was low on T1-weighted MR images and inhomogeneously high on T2-weighted images, which correlated pathologically with the presence of crystal cholesterol, hair, sebaceous glands, and epithelial cells in all cases. On MR, brain parenchyma showed little edema or other reaction to the masses, which were typically large. The value of MR over CT in the examination of ruptured dermoid cysts is the conspicuity of the extent of subarachnoid spread, involvement of the extraaxial structures, and evidence of vascular compromise, which can obviate angiography. MR had no advantage over CT in making the initial diagnosis of ruptured dermoid, but it would be the preferred preoperative study.

Improvement in CT pelvimetry.

When computed tomographic (CT) digital radiography is used for pelvimetry, measurement error may occur. Geometric distortion in the lateral direction of the CT digital radiograph can lead to an error in any measurement of the transverse pelvic inlet. The authors measured the magnitude of this error on two scanners and present a general method for correction of this potential error. The authors also showed that an additional dose reduction is possible if the patient is imaged in the posteroanterior rather than anteroposterior projection.

Scintigraphic measurement of oropharyngeal transit in man.

Scintigraphic studies of the oropharyngeal transit of a liquid bolus were performed in 15 healthy controls, 12 patients with symptoms of oral-pharyngeal dysphagia, and 13 patients with neuromuscular disease, who did not have dysphagia. Gamma camera imaging of the head, neck, and upper thorax was undertaken, in the lateral projection, during the swallowing of the radiolabeled bolus of water. Inspection of summed images permitted the selection of regions of interest (ROI) to represent the mouth, pharynx, and upper esophagus. Transit times between each ROI were calculated and compared. Significant prolongation of bolus transit time between the mouth and esophagus was present in both patients with and without dysphagia (0.59 +/- 0.38 sec and 0.33 +/- 0.7 sec; mean +/- SD, respectively) compared with controls (0.26 +/- 0.04 sec P less than 0.001, P less than 0.01, respectively, Mann-Whitney U test). Repeat studies in 25 individuals indicated that the transit measurements were more reproducible between swallows in normal subjects than in patients with symptoms. Deglutitive scintigraphy provides a noninvasive technique for the quantitative study of swallowing and its disorders.

Nonosseous accumulation of bone-seeking radiopharmaceuticals.

Bone scintigrams are usually obtained for evaluation of skeletal abnormalities; soft-tissue abnormalities are often an unexpected finding. However, the recognition of specific conditions with extraskeletal accumulation of bone-seeking radiopharmaceuticals greatly enhances the diagnostic value of the study. Several examples of abnormal nonosseous uptake in both neoplastic and nonneoplastic processes involving the brain, lung, heart, breast, bowel, liver, spleen, skeletal muscle, kidney, and bladder are presented. Examples of artifactual uptake in the soft tissues are also described. Causes for nonosseous accumulation are discussed.

Dermal grafts of the temporomandibular joint: postoperative appearance on MR images.

Complications may follow meniscectomy and placement of an allogenic implant in temporomandibular joint (TMJ) dysfunction. To characterize the anatomy of autogenous dermal grafts for repair and repositioning of the meniscus, the authors performed T1-weighted magnetic resonance (MR) imaging of 20 TMJs in 10 patients 6-23 months after surgery that was considered successful. MR imaging did not enable detection of the dermal grafts. Comparison of preoperative and postoperative MR images revealed little, if any, change in meniscal position. MR images of 20 menisci revealed anterior displacement (n = 11), normal position (n = 4), focal areas of increased signal intensity (n = 4), fragmentation (n = 2), and suboptimal visualization (n = 5). MR images of 20 condyles revealed normal features (n = 11), erosions (n = 2), early avascular necrosis (AVN) or subchondral cysts (n = 2), AVN (n = 3), an osteophyte (n = 1), and loss of bone (n = 2). One TMJ demonstrated increased soft tissue in the bilaminar zone.

A prospective study of femoral versus subclavian vein catheterization during cardiac arrest.

Femoral vein catheterization has advantages over subclavian vein catheterization during cardiac arrest in that there is minimal interference to ongoing CPR. In addition, risks of subclavian catheterization are not a factor in femoral vein catheterization. Few studies have compared the success rate for catheterization of one site with that of the other during cardiac arrest. We conducted a prospective study to compare the success and complication rates for femoral with those of subclavian vein catheterization. Ninety-four patients undergoing CPR had either femoral or subclavian vein catheters placed during the course of the arrest. Catheter placement was verified by injection of radiopaque contrast material. We found that the success rate for femoral catheterization was 77% compared with a success rate of 94% for subclavian vein catheterization (P less than .05). There were no instances of pneumothorax with subclavian vein catheterization. There was no apparent learning curve leading to an increased success rate during the course of the study. We conclude that femoral vein catheterization should not be used except in those instances where attempts at peripheral and central venous cannulation are unsuccessful.

Magnetic resonance imaging of a third trimester abdominal pregnancy.

Abdominal pregnancies are rare, representing 1% of all ectopic pregnancies. Early and accurate diagnosis is essential in order to avoid the serious complications associated with the condition, including catastrophic hemorrhage secondary to placental separation. The clinical presentation of abdominal pregnancy is extremely variable and physical examination by itself may be insufficient for diagnosis. Ultrasound (US) is currently the imaging method of choice for establishing gestational location, but sonographic interpretation may be difficult due to gas within the gastrointestinal tract and distorted pelvic anatomy. The use of magnetic resonance imaging (MRI) in obstetric diagnosis, including abdominal pregnancy, has been described. We report a case of an abdominal pregnancy of 32 wk gestation diagnosed by MRI.