DTPA Uptake Research Articles

New Multi-Parameters Combination of Technetium-99m-Diethylene-Triamine-Pentaacetate Orbital Single-Photon Emission Computed Tomography/Computed Tomography for the Evaluation of Graves’ Orbitopathy Activity

ABSTRACT Purpose This study investigates the new combined parameters of 99mTc-DTPA orbital single-photon emission computed tomography/computed tomography (SPECT/CT) for the evaluation of Graves’ orbitopathy (GO) activity. Methods A retrospective analysis was performed on 41 patients. All the patients undergone the 99mTc-DTPA orbital SPECT/CT and were categorized into active and inactive group based on the standard combined by the clinical active score (CAS), magnet resonance imaging (MRI) and/or follow-up results. Quantitative parameters of lacrimal gland (LG) including the protruding degree of lacrimal gland herniation (LGH) and uptake ratios (URs) of region of interest (ROI) drawn on lacrimal gland and occipital bone. SPECT/CT reading results were based on visual analysis. Parameters were compared between the two groups and the diagnostic value on discrimination of GO activity was also evaluated. Results All parameters of SPECT/CT for active GO groups were significantly higher than those of the inactive groups (p<.05). There were notable linear positive correlations between the assumption standard and readings as well as combination models 2 and 3 (r = .794, r = .772, r = .760, respectively). ROC analysis indicated that model 2 provided the highest diagnostic performance, exhibiting an area under the curve (AUC) of .947, a sensitivity of 92.7%, and a specificity of 88.6%. Conclusions The combined use of SPECT/CT reading results and DTPA uptake parameters of LG offers a more objective and precise evaluation of active GO. This study further recommends 99mTc-DTPA SPECT/CT might be serving as a supplementary beneficial approach for CAS in evaluating GO activity.

Incidental Detection of Ilium Langerhans Cell Histiocytosis on 99mTc-DTPA Renal Dynamic Scintigraphy.

We report the case of a 24-year-old man who underwent 99mTc-DTPA scintigraphy for the evaluation the renal function. This scan incidentally showed an abnormal uptake of 99mTc-DTPA in the left lower abdominal region. SPECT/CT fusion images showed osteolytic bone destruction in the left ilium associated with soft tissue mass and elevated DTPA uptake. Biopsy pathology of the ilium lesion demonstrated Langerhans cell histiocytosis.

The Role of Tc-99m DTPA Renal Dynamic Scintigraphy in Retroperitoneal Liposarcoma

Purpose Technetium-99m diethylene triamine pentaacetic acid (Tc-99m DTPA) renal dynamic scintigraphy is a widely used imaging technique that evaluates renal function of patients with extrarenal abnormalities, but its clinical value in potentially offering us information on proliferation of liposarcoma has not yet been reported. Methods We retrospectively reviewed 7 patients with histopathologically confirmed retroperitoneal liposarcoma who underwent Tc-99m DTPA renal dynamic scintigraphy. The clinical data, histopathological findings, Glomerular Filtration Rate (GFR), and Tc-99m DTPA uptake were recorded. Results Dedifferentiated liposarcoma and well-differentiated liposarcoma showed dissimilar degrees of Tc-99m DTPA uptake, an observation that correlated with Ki-67 expression (p < 0.01). 4 of the 7 patients were diagnosed with dedifferentiated liposarcoma, showing a moderate uptake of Tc-99m DTPA and greater than 20% Ki-67 expression on histological slides. Meanwhile, the remaining 3 patients, diagnosed with well-differentiated liposarcoma, showed no uptake of Tc-99m DTPA and Ki-67 expression of less than 5%. Conclusions This study suggests that Tc-99m DTPA renal dynamic scintigraphy provides diagnostic value in patients with retroperitoneal liposarcoma, not only in evaluating renal function but also in visualizing lesion-related radionuclide uptake, which may potentially offer further clinical insights into tumor proliferation and provide prognostic value for clinical outcomes in patients with retroperitoneal liposarcoma.

Evaluation of inflammatory activity in thyroid associated ophthalmopathy by SPECT/CT with 99mTc-DTPA

To evaluate the inflammatory activity in thyroid associated ophthalmopathy (TAO) by 99mTc-diethylene triamine pentaaceticacid (99mTc-DTPA) orbital single-photon emission computed tomography (SPECT)/CT. Methods: A total of 48 patients were enrolled from Xiangya Hospital of Central South University between October 2016 and March 2017. According to clinical active score (CAS), 93 eyes were divided into a TAO active group (n=72) and a TAO inactive group (n=21). All patients underwent 99mTc-DTPA orbital SPECT/CT examination, and the DTPA uptake in extraocular muscle belly was supposed to be positive. The results of 99mTc-DTPA orbital SPECT/CT examination were compared with those of CAS score evaluation. Results: The uptake rate (UR) of 99mTc-DTPA in the TAO active group was higher than that in the TAO inactive group (P<0.01). There was a linear positive correlation between UR and its CAS scores in all patients (r=0.767, P<0.01). Five cases (7 eyes) showed inconsistent results between 99mTc-DTPA orbital SPECT/CT examination and CAS score. Among the 7 eyes, 6 eyes showed myocarditis lesions in 99mTc-DTPA orbital SPECT/CT examination while its CAS was no more than 3; meanwhile, there was 1 eye with CAS>3, but 99mTc-DTPA orbital SPECT/CT examination showed negative myocarditis lesions. Conclusion: 99mTc-DTPA orbital SPECT/CT is consistent with the CAS score in evaluation of the disease activity of TAO; 99mTc-DTPA orbital SPECT/CT may be more objective and accurate to evaluate TAO than CAS.

Rapid response to and long-term effectiveness of anti-CD20 antibody in conventional therapy resistant Graves’ orbitopathy: A five-year follow-up study

The aim of this investigations was to study the effectiveness of anti-CD20 antibody therapy in Graves’ orbitopathy (GO) resistant to glucocorticoids. Five patients were entered in the study. The protocol required no improvement of orbital status after a recent course of glucocorticoids. Activity of GO was confirmed by three independent techniques: clinical activity score (CAS), 99mTc-labeled diethylene triamine pentaacetic acid (99mTc DTPA) single photon emission computed tomography and magnetic resonance imaging. Rituximab (RTX) was given as weekly infusions of 375 mg/m2 body surface area for four weeks. The mean follow-up period was 67 (range 58–81) months. Improvement of GO has been observed in all patients: CAS before therapy was 6.5 ± 1.7 and decreased to 3.4 ± 1.6 by one month (p < 0.05) and remained unchanged (3.2 ± 1.7) at 12 months. No further CAS change, in either direction, was detected during the yearly follow-up visits. The mean DTPA uptake before therapy was 16.52 ± 4.51 MBq/cm3 and decreased to 11.97 ± 2.36 MBq/cm3 at one year (p < 0.002). The mean of T2 relaxation times before and one year after therapy were 96.91 ± 17.61 ms and 84.29 ± 9.41 ms, respectively (p < 0.001). The mean serum TSH receptor antibody (TRAb) levels before therapy, at the one month and one year control visits were 7.4 ± 3.4 U/L, 5.6 ± 4.5 U/L and 1.7 ± 1.5 U/L, respectively (p < 0.004). No correlation between changes of TRAb and activity parameters has been found. Anti-CD20 treatment seems to influence positively the clinical course of GO, and this effect seems to be stable for five years. To our knowledge, this is the longest published follow-up of RTX treatment in GO.

Improved measurement of the glomerular filtration rate from Tc-99m DTPA scintigraphy in patients following nephrectomy

ObjectiveWe aimed to improve Tc-99m DTPA glomerular filtration rate (GFR) scintigraphy (Gates’ method) in a prospective study using Cr-51 EDTA GFR test as a gold standard.MethodsFifty-seven Tc-99m DTPA GFR scintigrams in 45 subjects (male/female = 33:12, age = 45.9 ± 17.6 years, 14 healthy volunteers and 31 nephrectomised patients) were compared using Cr-51 EDTA GFR tests. Using the %renal uptake of Tc-99m DTPA and Cr-51 EDTA GFR, a revised equation for GFR was established through linear regression analysis.ResultsThe revised equation for improved GFR was GFR(mL/min) = (%renal uptake × 11.7773) − 0.7354. Gates’ original GFRs (70.1 ± 20.5 mL/min/1.73 m2) were significantly lower than Cr-51 EDTA GFRs (97.0 ± 31.9 mL/min/1.73 m2; P < 0.0001), but the improved GFRs (98.0 ± 26.3 mL/min/1.73 m2) were not different from (P = 0.7360) and had a significant correlation with (r = 0.73, P < 0.0001) the Cr-51 EDTA GFRs. The revised GFR equation effectively demonstrated perioperative GFR changes in kidneys that were operated on and the contralateral kidneys at 3 and 6 months post-partial nephrectomy (n = 25).ConclusionsGFR measurement using Tc-99m DTPA scintigraphy could be significantly improved by a revised equation derived from the comparison with Cr-51 EDTA GFR.Key Points• Measurement of glomerular filtration rate is difficult following nephrectomy.• Measurements can be significantly improved by new renal sctintigraphic methods.• This helps physicians to measure kidney function of patients following nephrectomy.• Management of renal tumour patients should become more effective.

The impact of 99mTc-DTPA orbital SPECT in patient selection for external radiation therapy in Graves’ ophthalmopathy

In Graves' ophthalmopathy (GO), there is a demand to differentiate the immunologically active disease state, when immunosuppressive therapy is necessary, from the inactive state, when the patient would not benefit from it. We measured the inflammatory activity in the retrobulbar region using Tc-diethylene triamine pentaacetic acid (DTPA) SPECT before and after external radiation to determine whether this method is suitable for predicting the effectiveness of this therapy. Thirty-two patients with suspected active GO were involved in this retrospective study. The initial image, DTPA uptake value (UV) and its change after therapy were assessed to monitor the effect of the therapy and investigate whether a pretreatment scan is capable of predicting the outcome. Depending on the change in DTPA UV after radiotherapy, three patient groups were formed: decreased, increased or minimally changed (less than 1×10 injected dose (ID)/ml). The initial DTPA UVs of these groups were significantly different (P<0.001). Improvement was observed mainly in patients with higher initial values. When comparing the groups with low (<12×10 ID/ml) versus high (≥12×10 ID/ml) initial uptake, an unexpected increase was observed in the first group after therapy (mean: +2.89±2.66×10 ID/ml), whereas the average change in the DTPA UV was negative in the latter group as anticipated (-2.24±4.47×10 ID/ml, P<0.00001). We found that in GO patients a high DTPA UV may predict the response to orbital radiation therapy. DTPA orbital SPECT may be a suitable technique for the selection of GO patients for radiation therapy.

Uptake of Gd-EOB-DTPA by hepatocellular carcinoma: Radiologic–pathologic correlation with special reference to bile production

The aim of this study was to reveal the relationship between intratumoral uptake of gadoliniumethoxylbenzyldiethylenetriaminepentaacetic acid (Gd-EOB-DTPA) of hepatocellular carcinoma (HCC) in the hepatobiliary phase and pathological features. Sixty HCC nodules were confirmed at pathology in 56 patients who had undergone dynamic MRI. T1-weighted 3D gradient echo sequences before and 20 min (hepatobiliary phase) after the injection of Gd-EOB-DTPA were performed. Uptake of Gd-EOB-DTPA was defined as an increase in signal intensity in the hepatobiliary phase compared with the precontrast scan. All surgical specimens were fixed with formalin and then digitally photographed. The relationship between Gd-EOB-DTPA uptake and histological findings, including a macroscopic greenish area, was examined. MR images showed uptake of Gd-EOB-DTPA in twenty-two nodules. Histological findings indicated twenty-six nodules contained a greenish area. There is a significant correlation between HCC showing Gd-EOB-DTPA uptake and the presence of a greenish area (p<0.001). On a nodule-by-nodule basis, more than two-thirds of the area of Gd-EOB DTPA uptake coincides with the greenish part in only 12 of 22 lesions (54.5%). More than two-thirds of the greenish area coincided with that of Gd-EOB-DTPA uptake in only 10 of 26 cases (38.5%). The area of Gd-EOB-DTPA uptake does not always match the greenish part, but HCC with uptake of Gd-EOB-DTPA significantly correlated with green HCC.

Retrobulbar 99mTc-Diethylenetriamine-Pentaacetic-Acid Uptake May Predict the Effectiveness of Immunosuppressive Therapy in Graves' Ophthalmopathy

In Graves' ophthalmopathy (GO), only patients with immunologically active disease respond to immunosuppressive therapy. Previous studies and theoretical considerations suggest that elevated orbital (99m)Tc-diethylenetriamine-pentaacetic-acid (DTPA) single photon emission computed tomography (SPECT) reflects inflammatory disease activity. We studied whether corticosteroid treatment causes a substantial decrease in DTPA uptake in GO, a result consistent with successful immunosuppressive treatment of GO and referred to as a favorable treatment outcome. One hundred fourteen orbits in 57 patients with active GO (CAS >or= 4) were entered into the study. All patients received corticosteroid treatment. Orbital DTPA uptakes were numerically quantified for the entire orbit as well as the anterior and posterior segments separately. DTPA SPECT was performed before, and 2 to 9 months after the initiation of immunosuppressive treatment. The normal range for DTPA uptake was established in 34 orbits of 17 patients who were being worked up for Raynaud's phenomenon and had no thyroid disease. The mean DTPA uptake of the 114 orbits of GO patients was higher prior to corticosteroid therapy than after this treatment (11.03 +/- 4.26 MBq/cm(3) and 9.84 +/- 3.51 MBq/cm(3), respectively, p < 0.001) but a substantial decline in DTPA uptake was seen in only 39.5% of GO patients. The positive predictive value of an initial DTPA >12.28 MBq/cm(3) for a substantial decline in DTPA uptake (favorable treatment outcome) was 76%, while a negative predictive value of a pretreatment DTPA <or=12.28 MBq/cm(3) was 78%. Corticosteriod treatment is associated with a decline in DTPA uptake in a fraction of GO patients. GO patients with a DTPA uptake above 12.28 MBq/cm(3) are more likely to have a favorable response to corticosteroid therapy while patients with lower values are less likely to have this potentially favorable response. An elevated DTPA uptake may identify patients who are most likely to benefit from immunosuppressive treatment.

Effects of short-term pH fluctuations on cadmium, nickel, lead, and zinc availability to ryegrass in a sewage sludge-amended field

In this field experiment, sewage sludge was applied at 0, 5, 10, and 50 t ha −1, and the availability of Cd, Ni, Pb, and Zn was assessed both by ryegrass uptake and by DTPA extractions. The aim was to investigate the role of important soil parameters, particularly pH, on heavy metal availability. It was found that metal uptake and extractability increased significantly in the 50 t ha −1 treatment. In the 16th week of the experiment there was a significant, although temporary, increase in DTPA-extractable Cd, Ni, and Zn concentrations. Metal concentrations in ryegrass were also significantly elevated in week 20 compared to the subsequent cuttings. These fluctuations in both DTPA and ryegrass uptake occurred only at 50 t ha −1 and were probably induced by a sudden pH decrease measured in the same treatment in week 16. This suggests that soils which have received high applications of sewage sludge may be prone to fluctuations in metal availability.

Quantitative magnetic resonance imaging of articular

Magnetic resonance imaging of articular cartilage has recently been recognized as a tool for the characterization of cartilage morphology, biochemistry and function. In this paper advancements in cartilage imaging, computation of cartilage volume and thickness, and measurement of relaxation times (T2 and T1Rho) are presented. In addition, the delayed uptake of Gadolinium DTPA as a marker of proteoglycan depletion is also reviewed. The cross-sectional and longitudinal studies using these imaging techniques show promise for cartilage assessment and for the study of osteoarthritis.

Prospective evaluation of malignant middle cerebral artery infarction with blood–brain barrier imaging using Tc-99m DTPA SPECT

Background: Malignant middle cerebral artery (MMCA) infarction is associated with severe brain edema which may lead to a rapid deterioration of consciousness, increase of intracranial pressure, brain midline shift and finally, herniation. We examined the correlation between the degree of the blood–brain barrier (BBB) permeability and MMCA. Methods: Twenty-five consecutive patients (17 men and 8 women, mean age 62.1 ± 10.1) were included in the study. Each patient had a daily clinical examination, and the neurological deficits were scored using NIHSS score. A CT without contrast material was performed in all patients. 99mTc-DTPA SPECT was performed at 36 h after the stroke. A quantitative index of BBB breakdown (disruption index) was calculated. Results: The mean volume of stroke was 138 ± 87 cm 3. The mean DTPA disruption index was 6.6 ± 4.6 (range 1.0–21.0). The mean NIHSS score was 14 ± 4 ( p = 0.2). Five of 25 patients had brain herniation as evidenced on brain CT. The volume of stroke was only marginally elevated in patients with herniation ( p = 0.062). All patients showed significant, inverse correlation between NIHSS score and DTPA uptake ( r = − 0.43, p = 0.033). There was a significant correlation between the extent of DTPA distribution (more than one vascular territory) and the occurrence of herniation ( p < 0.001). Conclusions: DTPA-SPECT imaging is a reliable complementary predictive tool in patients with an MCA stroke. The specific pattern found on DTPA SPECT, compatible with diffuse BBB disruption, may be of value in predicting “malignant MCA.”

In vivo imaging of apoptosis in patients with acute stroke: Correlation with blood–brain barrier permeability

Background: We wished to determine the ability of radiolabeled annexin V to concentrate at sites of ischemic injury in patients with acute cerebral stroke. Secondly, we sought to correlate annexin V imaging in these patients with the degree of blood–brain barrier (BBB) breakdown. Methods: Twelve patients with acute stroke had a complete neurological examination, including the National Institutes of Health (NIH) stroke scale and the Glasgow Coma Score (GCS). A non-contrast CT scan was performed on all patients. A SPECT of the brain was obtained 2 h after injection of annexin V. The integrity of the BBB was evaluated in seven patients using Tc-99m-DTPA brain SPECT. Results: All patients had an infarct in the MCA territory. Eight patients had abnormal increased annexin V activity, which was more common in patients with cortical strokes ( P = 0.01). The concentration of annexin had no correlation to the volume of stroke, but it was significantly and inversely related to the GCS on admission ( r = −0.7, P = 0.02). Foci of apoptosis were noted contralateral to the affected hemisphere as well. All seven patients who underwent DTPA SPECT showed breakdown of the BBB. DTPA uptake was significantly and positively associated with NIH score ( r = 0.80, P = 0.01) and inversely associated with GCS ( r = −0.89, P = −0.03). Conclusion: This study shows that it is possible to identify in vivo regions of ischemic neuronal injury using radiolabeled annexin V in patients with acute stroke. Annexin imaging can play a major role in the selection of therapy in the initial period following stroke in adults.

Incidental DTPA and DMSA uptake during renal scanning in unknown bone metastases

We report a patient with DTPA and DMSA uptake on unsuspected bone metastases. He had severe pain due to grade 3 hydronephrosis of his left kidney. When Tc-99m DTPA and DMSA renal scanning were performed for preoperative evaluation, abnormal radiopharmaceutical uptake on the iliac area was noted. Pancreatic adenocarcinoma metastases to bone were subsequently defined. This patient is a very demonstrative case in respect of having all DTPA, DMSA and HDP uptakes in bone metastases. The type of the tumor has to be added to the list of extrarenal uptake of DTPA and DMSA as a rare cause.

Hypoactive Area Detected During Tc-99m DTPA Renal Scintigraphy: An Unusual Appearance

Tc 99m DTPA renal scintigraphy was applied for the evaluation of renal function of a 45 years old man who had been diagnosed to have end stage renal failure and was treated with continuous ambulatory peritoneal dialysis. Renal scintigraphy revealed findings of chronic renal failure. Furthermore, absence of radiotracer uptake area was observed on the lateral side of the spleen. No pathological invention was determined on this area but liquid collection was observed in both abdominal ultrasonographic examinations. This appearance seemed to belong to collection of dialysate fluid given during peritoneal dialysis. Figure 1 Figure 1: Renal perfusion was delayed and decreased in renographic flow images (10 mCi Tc99m-DTPA – 128x128 matrixes, 1 sec/frame, total 60 frames) at both kidneys. In addition, suspicious decreased uptake appearance was observed on the lateral side of spleen in delayed perfusion images. Figure 2 Figure 2: Severe function loss was observed in both kidneys and background activity was found to be high in renal function images (128x128 matrix, 1dak/frame, total 24 frame). Decreased uptake area was observed on the lateral side of the spleen. In addition, increased perfusion area was observed at inferolateral neighborhood of left kidney, compared to other areas of abdomen. Hypoactive Area Detected During Tc-99m DTPA Renal Scintigraphy: An Unusual Appearance 2 of 4 Figure 3 Figure 3: Region of interests and curves of Tc 99m DTPA renal scintigraphy were shown in the figure. GFR was calculated to be 5ml/min in the left kidney and 7ml/ min in the right kidney. The diagnosis of bilateral renal failure was supported when function images and renogram were evaluated together. In the laboratory examination of the samples from the patient, creatinine clearance and urea clearance were found to be 9 ml/min and 6 ml/min respectively. The mean GFR was calculated as 7,5 ml/min. Figure 4 Figure 4: The illustration of initial 10 images was composed. By this way, decreased uptake area on the lateral side of spleen became more distinct. Furthermore, by this way, hypervascular area observed on inferior neighborhood of left kidney became more distinguishable. Figure 5 Figure 5: The illustration of abdominal ultrasonography. In abdominal ultrasonographic examination; parenchymal echo was found to be grade 3 increased and grade 1-2 pelvic ecstasies were observed in both kidneys. Anechoic free liquid appearance was shown on the perisplenic area. Bowel loops and omentum were shifted to the midline because of prevalent free anechoic liquid in abdomen. No pathological invention was determined in hypervascular area on renal scintigraphy. Variable pathological decreased uptake aspects may be seen on renal scintigraphy as abscess, cyst, lymphocele and tumor etc (1,2,3). Therefore, abdominal ultrasonography must be performed to patient for differential diagnosis. For this reason, this appearance was thought to be depending on the shift of bowel loops and omentum. Abnormal DTPA uptake, a decrease or an increase, may be observed during the renal scintigraphy in many diseases. There are many factors to be considered on differential diagnosis. If there is a decreased uptake, causes of perisplenic fluid collection such as peritoneal dialysis, cirrhosis, hepatic tumors, etc must be kept in mind. In addition, it should be known that hypervascular appearance in the scintigraphic evaluation of the abdomen might due to shift of bowel loops and omentum to the midline due free collection.

The effects of pentoxifylline on renal function and free radical production in unilateral ureteral obstruction.

There is an ongoing discussion about ureteral obstruction-related renal dysfunction. In this study, we aimed to test the effect of pentoxifylline (PTX) on both kidneys in unilateral ureteral obstruction (UUO), and to determine its interaction of with prostaglandin E2 (PGE2), and diclofenac sodium (DIS). A sham operation was performed in group 1. Placebo, PTX, DIS, and PTX+DIS were administrated to groups 2, 3, 4 and 5, respectively. The left ureter was ligated in all groups except group 1. At 24 h, technetium 99m diethylenetriamine penta-acetic acid scintigraphy was performed to determine renal function. Additionally, the tissue levels of thiobarbituric acid reactive substances (TBARS) and PGE2 in both kidneys were measured to determine cytotoxic and cytoprotective mechanisms. When the ipsilateral kidneys were evaluated: (1) UUO significantly reduced DTPA uptake and none of the medications used prevented the reduction, (2) UUO significantly increased TBARS production, and only PTX prevented the increase, (3) UUO caused a significant increase in PGE2 production, and only DIS significantly decreased this. When the contralateral kidneys were evaluated: (1) UUO significantly increased DTPA uptake but DIS and PTX+DIS prevented this, (2) UUO significantly elevated TBARS levels and DIS and PTX+DIS caused an additional elevation, (3) UUO significantly increased PGE2 production, and only DIS prevented this. In conclusion, UUO caused ipsilateral renal hypofunction and contralateral hyperfunction, which are related to increased TBARS and PGE2 levels. PTX markedly decreased free radical activity in the ipsilateral kidney. While PTX showed a placebo effect, DIS prevented the compensatory contralateral renal response through increased TBARS and decreased PGE2 levels. The beneficial effect of PTX on the ipsilateral kidney, and the hazardous effect of DIS on the contralateral kidney may be explained by more complex interactions among TBARS, PGE2, PTX, DIS and UUO-related renal dysfunction.

Effect of region of interest selection and uptake measurement on glomerular filtration rate measured by 99mTc-DTPA scintigraphy in dogs.

Determinations of different methods of measurement of uptake of 99mTc-DTPA using scintigraphy of glomerular filtration rate (GFR) were made from 29 studies on 10 healthy beagle dogs. GFR was measured by calculating the percentage dose uptake (integral method) and rate of uptake (slope method) of 99mTc-DTPA using manual kidney regions of interest (ROI) and automatic kidney and background ROIs at different time periods of the uptake phase. These results were compared using linear regression analysis to the GFR obtained from 99mTc-DTPA plasma clearance using multiple blood samples. The best correlation coefficient between percentage DTPA uptake and GFR by DTPA clearance (r = 0.84, P < 0.001) was derived from time intervals between 30s-120s with a perirenal background ROI at 1 or 2 pixels out from the kidney ROI using automatic kidney ROI at 20% threshold. With the slope method, the best correlation coefficient (r = 0.85, P < 0.001) was obtained from time intervals between 30s-peak with the background ROI at 2 pixels out from the kidney ROI using automatic ROI at 35% threshold. The offset was higher, and the correlation varied more with different ROIs and the method was unreliable at time intervals extending beyond the peak radioactivity. Manual kidney ROIs with automatic background ROIs had slightly lower correlations. With DTPA renography both integral and slope uptake method with automatic kidney and background ROIs are accurate methods to estimate the GFR, but that the integral method is much more stable to variations in ROI size and the duration of the uptake phase of the renogram.

Noninvasive assessment of the functional neovasculature in 9L-glioma growing in rat brain by dynamic 1H magnetic resonance imaging of gadolinium uptake.

Pathophysiologic parameters of the functional neovasculature and the blood-brain barrier of 9L-glioma in rat brain were measured noninvasively by dynamic 1H magnetic resonance imaging studies of gadolinium (Gd)-DTPA uptake. Changes of apparent [Gd-DTPA] uptake in time (CT[t]) were analyzed in a slice through the center of 10 9L-gliomas using fast T1 measurements. The distribution of the contrast agent was spatially correlated with the distribution of perfused microvessels as determined by immunohistochemical analysis. This method permits a distinction between perfused and nonperfused microvessels with a disrupted blood-brain barrier. In transverse slices of the whole tumor, a spatial correlation was observed between CT maps and the two-dimensional distribution of perfused microvessels. In the next step, Gd-DTPA uptake rates were spatially related to the perfused microvessel density (Np) or vascular surface area (Sp). In tumor voxels with perfused microvessels, a linear correlation was found between Gd-DTPA uptake rate constants (k values) and Np or Sp. No correlation was observed between k values and the total microvessel density. These are the first data that show a relation between Gd-DTPA uptake rates and parameters of the functional neovasculature in 9L-glioma growing in rat brain. Now that Gd-DTPA uptake studies can be related to parameters of the functional neovasculature, they may be used more efficiently as a prognostic tool before or during therapy.

Ammonia concentration in the renal veins in unilateral renal artery stenosis with hypertension.

We measured blood ammonia in pre-angioplasty samples from the renal veins, aorta and inferior vena cava of 15 patients with hypertension due to unilateral renal artery stenosis confirmed by arteriography. Patients with renal insufficiency or small kidneys were excluded. Mean ammonia values were microgram/dl: vein of affected kidney, 106.00 +/- 12.75; vein of unaffected kidney, 75.65 +/- 23.10; aorta 61.04 +/- 15.00; vena cava, 62.44 +/- 19.65. The value for the affected kidney was significantly higher than the other three values (p < 0.001). Mean +/- SD DTPA uptake (%) was 42.8 +/- 2.21 in the affected kidney and 56.53 +/- 3.64 in the unaffected kidney. This difference did not correlate significantly with that of the ammonia concentrations tau = -0.292).

Dynamic Contrast-Enhanced Magnetic Resonance Imaging of the Breast Combined with Pharmacokinetic Analysis of Gadolinium-DTPA Uptake in the Diagnosis of Local Recurrence of Early Stage Breast Carcinoma

This study was designed to assess the efficacy of dynamic contrast-enhanced magnetic resonance imaging (MRI) of the breast combined with pharmacokinetic analysis of gadolinium (Gd)-DTPA uptake in the diagnosis of local recurrence of early stage breast carcinoma. Fifty women treated with breast-conserving surgery and radiotherapy underwent breast MRI. Dynamic magnetic resonance data obtained at four preselected slice locations were analyzed to examine Gd-DTPA uptake based on a pharmacokinetic model using three parameters: wash-in rate, wash-out rate, and amplitude of uptake. Synthetic images were produced from the above parameters and their derivatives--maximum uptake and reciprocal of half the time to maximum. For each region of interest (ROI), median parameter values were calculated. The mean pixel signal intensity of each ROI was plotted against time, and an enhancement index was determined. Sixty ROIs were selected: 49 lesions were benign, and 11, malignant. Significant differences between benign and malignant lesions were found for the enhancement index (P < 0.0001), maximum uptake (P < 0.0001), amplitude of uptake (P < 0.0001), wash-in rate (P = 0.03), wash-out rate (P = 0.01), and the reciprocal of half the time to maximum (P = 0.0005). The respective sensitivities and specificities were as follows: for the enhancement index, 1.00 and 0.96; for maximum uptake, 1.00 and 0.96; for amplitude of uptake, 0.91 and 0.94; for wash-in rate 0.82 and 0.47; for wash-out rate 0.91 and 0.59; and for the reciprocal of half the time to maximum, 1.00 and 0.51. Dynamic scanning proved essential for the detection and differential diagnosis of local tumor recurrence. Pharmacokinetic analysis of Gd-DTPA uptake can be used to produce parametric images that retain the spatial resolution of the original images while providing additional information about lesion permeability and vascularity, and helping to avoid the observer variability associated with ROI analysis.