MRI follow-up after free tendon graft reconstruction of the thumb ulnar collateral ligament.

OBJECTIVE: Our aim was to analyse whether MRI is useful in the follow-up of reconstruction of the ulnar collateral ligament (UCL) of the metacarpophalangeal joint of the thumb, to describe normal postoperative findings, and to evaluate different MR sequences. MATERIAL AND METHODS: Our study material consists of 10 patients who, because of a chronic rupture of the ulnar collateral ligament of the thumb, had been operatively treated using a free tendon graft. The patients were, in addition to the clinical examination and radiographs, also imaged using MRI both pre- and postoperatively. The postoperative MRI controls, undertaken at 2, 12 and 24 months were analysed without knowledge of the clinical or radiographic findings. RESULTS: The reconstructed UCL was well visualised on MRI. One graft rupture was diagnosed on MRI and was later operatively confirmed. No increase in osteoarthritis of the metacarpophalangeal (MP) joint of the thumb was seen during the follow-up. The single most informative MR sequence was T2TSE in the coronal plane. CONCLUSION: Magnetic resonance imaging may provide a clinically valuable means of assessing graft integrity in patients with suspected postoperative graft failure after UCL reconstruction, although we do not consider MRI necessary in the routine follow-up of patients with an uneventful recovery.

Effect of clinical audits of radiation use in one hospital district in Finland.

BACKGROUND: A clinical audit is a systematic, independent, and documented process to improve the quality of radiological processes and radiation safety for patients. PURPOSE: To evaluate the effect of an audit process by comparing the results of two consecutive audits at the same units. MATERIAL AND METHODS: Audits were carried out twice at each imaging unit in the southwest hospital district of Finland: first, at the end of 2003, and again in November 2007. Both evaluations were carried out in a similar way: by interviewing personnel and examining documents, independent experts from other hospital districts ensured that diagnostic medical imaging processes at each unit were carried out according to generally accepted standards for good medical radiological procedures. The results of the consecutive audits were compared in order to analyze the effects of the clinical audits. RESULTS: The use of radiation was in accordance with the requirements and standards of good medical procedures at every audited unit during both evaluations. The list of audit criteria was fulfilled satisfactorily on both occasions at all of the audited units, and clearly better during the second run. In the first audit, the auditors made 80 recommendations for improving diagnostic procedures and, in the second audit, 53 recommendations. During the first audit, most of the recommendations (22/80) concerned instructions in the fundamental practice of examining a patient. During the second audit, most recommendations were in the category of radiation doses. CONCLUSION: The clinical audit had a positive impact on the practice of work procedures in radiological departments. Most of the recommendations made after the first audit had been taken into consideration by the time of the second audit.

Visual scoring of atherosclerosis in chest computed tomography: findings among male construction workers.

BACKGROUND: Standard chest computed tomography (CT) examinations may contain valuable and underused information on atherosclerosis. PURPOSE: To study the retrospective scoring of chest atherosclerosis in CT studies performed for reasons other than cardiovascular. MATERIAL AND METHODS: Unenhanced CT images originally used for lung cancer screening of 505 male construction workers were retrospectively analyzed for chest atherosclerotic calcifications (coronary, aortic, and precervical artery origins). Findings were compared between those with a prediagnosed cardiovascular disease or diabetes (n = 180) and disease-free subjects (n = 325). RESULTS: Arterial calcifications (all) occurred among 96.6% of the subjects and coronary calcifications among 91.7%. The average total calcium score of the diseased subjects was 8.34 vs. 5.13 in the disease-free group (P<0.001). All calcification scores increased with age. In multivariable analyses, systolic blood pressure, erythrocyte sedimentation rate, and smoking were generally associated with high scores, while high stature and high diastolic blood pressure were mainly associated with low scores. Nonsignificant positive associations between asbestos exposure and coronary calcifications were found. CONCLUSION: Our scoring method agreed well with preknown cardiovascular risk factors, indicating the method's usability. Chest CT examinations contain valuable information concerning atherosclerosis. This can be used epidemiologically or to reveal occult atherosclerotic disease.

Clinical, radiographic and MRI findings of the temporomandibular joint in patients with different rheumatic diseases.

The aim of this study was to investigate the condition of the temporomandibular joint (TMJ) in patients with different rheumatic diseases, and report correlations between the clinical, radiographic and magnetic resonance imaging (MRI) findings. The 67 patients were divided into four groups: 16 with rheumatoid arthritis (RA), 15 with mixed connective tissue disease (MCTD), 18 with ankylosing spondylitis (AS) and 18 with spondyloarthropathy (SPA). They were clinically examined, and panoramic tomography, lateral panoramic radiography and MRI of the TMJ were performed. MRI showed reduced articular cartilage in 25% (4/16) of RA, 0% (0/15) of MCTD, 17% (3/18) of AS and 17% (3/18) of SPA patients. Condylar changes included erosion, osteophytes and abnormal shape. Disc alterations included perforation, abnormal anterior position and decreased movement. These abnormalities were most frequent in RA patients, and least frequent in MCTD and SPA patients. Crepitation and reduced maximum opening of the mouth correlated with abnormalities of the disc and articular cartilage as shown by MRI. Severe condylar erosion in panoramic tomograms significantly correlated with MRI findings of condylar erosion (P<0.01), diminished thickness of condylar cartilage, abnormal condylar shape, and abnormal shape of the temporal surface of the TMJ (P< or =0.001). The presence of crepitation, limited mandibular movement and/or pain on movement of the jaw often indicated structural damage to the TMJ. Panoramic radiographs provide an alternative method to MRI but, to obtain a more detailed anatomic picture, MRI is recommended for patients with acute unexplained pain or as part of preoperative work up. A panoramic recording is not indicated when MRI is planned.

Magnetic resonance imaging findings in Finnish Spitz dogs with focal epilepsy.

Eleven Finnish Spitz dogs with focal seizures and 3 healthy controls were evaluated. General clinical and neurological examinations, blood examination, urinalysis, cerebrospinal fluid examination, electroencephalography (EEG), and magnetic resonance imaging (MRI) of the brain were performed on all dogs. On EEG examination, focal epileptic activity was found in 7 of 11 dogs (64%), and generalized epileptic activity was observed in 4 of 11 dogs (36%). MRI (performed with 1.5 T equipment) detected changes in 1 epileptic dog. Mild contrast enhancement after gadolinium injection was identified in this dog's right parietal cortex. However, no such changes were observed in repeated magnetic resonance images. Special emphasis was given to seizure history to determine any correlations between seizure intervals and MRI findings. Our results indicate that Finnish Spitz dogs with focal seizures suffer from focal idiopathic epilepsy and have nondetectable findings on MRI or pathology. MRI showed poor sensitivity in detecting epileptogenic areas in our patients with focal seizures. Reversible MRI changes in 1 dog could have been caused by seizures.

Bronchoalveolar lavage fluid findings following radiotherapy for non-small cell lung cancer.

PURPOSE: To evaluate the diagnostic potential of bronchoalveolar lavage fluid analysis in radiation-induced lung injury. METHODS AND MATERIALS: Thirty patients with inoperable non-small cell lung cancer received either high-dose hyperfractionated radiotherapy or radiotherapy and interferon, a potential radiosensitizer, or radiotherapy and N-acetylcysteine, a potential radioprotector. Bronchoalveolar lavages were performed before and immediately after radiotherapy, and thereafter 6-8 weeks and 3 months after radiotherapy. Total and differential cell counts were measured from the bronchoalveolar lavage fluid samples. Urea measured in serum and in bronchoalveolar lavage fluid was used to calculate epithelial lining fluid. The concentrations of protein and phosphatidylcholine, the major surfactant phospholipid, in epithelial lining fluid were measured. The extent of radiation-induced lung injury was assessed from computed tomographies performed before radiotherapy, and 6-8 weeks and 3 months after radiotherapy. RESULTS: More patients in the interferon-arm developed radiation pneumonitis than did patients in the other groups, but no significant differences in alveolar fluid indices were noted between the groups. When all the patients were studied together, radiation was shown to have induced a significant relative increase of lymphocytes in bronchoalveolar lavage fluid 6-8 weeks and 3 months after the end of radiotherapy. The concentration of phosphatidylcholine in epithelial lining fluid decreased significantly 6-8 weeks and 3 months after treatment. The increase in protein concentration in epithelial lining fluid reached a statistically significant level 6-8 weeks after radiotherapy. CONCLUSION: Analysis of bronchoalveolar lavage fluid predicts the degree of radiation pneumonitis; however, radiology remains to be "the gold standard."

Procollagen-III in serum, plasminogen activation and fibronectin in bronchoalveolar lavage fluid during and following irradiation of human lung.

In the search for predictors of late radiation-induced lung injury we studied procollagen type III peptide concentration (P-III-P) in serum as well as fibronectin and plasminogen activation in bronchoalveolar lavage (BAL) fluid during and following irradiation of human lung. The patients received either high-dose hemithorax irradiation for pleural mesothelioma (11 patients) or high-dose irradiation with individually shaped fields for non-small cell lung cancer (12 patients). The severity of radiation fibrosis was assessed clinically from CT scans 6 months and 12 months after treatment. Four scores were used: severe, moderate, mild, or normal. Radiological lung injury varied from "severe" (9 patients) to near absence of injury-"normal" (6 patients). Serum levels of P-III-P, when measured weekly during the 5-week period of radiotherapy or at several time-points after treatment, did not show consistent changes, nor did the levels correlate with the score for radiation fibrosis as assessed by CT scanning. Changes in fibronectin levels or in markers of plasminogen activation in BAL fluid did not correlate with the development of late lung injury. The levels of BAL fluid plasmin and plasminogen activator as assessed zymographically, but not the free net enzyme values, showed a tendency to be elevated in patients with severe radiation-induced lung injury, suggesting a possible role for inhibitors of the plasminogen activation cascade in the process of radiation-induced lung injury.

Natural alpha-interferon in combination with hyperfractionated radiotherapy in the treatment of non-small cell lung cancer.

Our previous study in patients with small-cell lung cancer indicated that natural alpha interferon might be a radiosensitiser. In this study we considered 20 patients with inoperable non-small cell lung cancer, who were randomly assigned to receive either hyperfractionation radiotherapy alone, 1.25 Gy twice a day (6 hr interval), 60 Gy/48F/32d; or the same radiotherapy concurrently with alpha interferon. Patients in the radiotherapy+alpha interferon arm received 3 x 10(6) IU natural alpha interferon intramuscularly and 1.5 x 10(6) IU inhaled via a dosimeter-equipped jet nebulizer 30 min before each radiotherapy session. Tumor response and radiation-induced lung injury were assessed by serial chest radiographs, computerized tomography scans and lung function studies, during a 1 year follow-up period. No patient in either arm achieved complete response. On the other hand, five patients in the radiotherapy arm and six in the radiotherapy+interferon arm experienced partial response, and the corresponding figures for stable disease were three and one. Combined treatment with radiotherapy and inhaled and intramuscular interferon proved feasible but laborious, for both patients and staff. Pneumonitis and/or oesophagitis in the radiotherapy+interferon arm were moderate to severe, and only two patients tolerated the treatment without any modifications. No treatment modifications were necessary in the radiotherapy arm. The early deaths in the radiotherapy+interferon arm may have been treatment-related. The optimal way to combine interferon and radiotherapy to further evaluate its role as a radiosensitiser needs further studies in larger series.

Multimodality treatment programs for malignant pleural mesothelioma using high-dose hemithorax irradiation.

The characteristic of malignant pleural mesothelioma is a tumor that grows by plate-like extension over the pleura, and invades adjacent tissues and organs. Radical surgical removal of the tumor is generally not possible, and most treatment regimens involve combined chemotherapy and radiotherapy, as well as debulking surgery. We have prospectively evaluated five locally-aggressive multi-modality treatment programs, using different hemithorax irradiation schedules and chemotherapy regimens. One hundred patients with confirmed malignant pleural mesothelioma entered the study between 1977 and 1989. The treatment programs, which can consecutively, were: I, 20 Gy (10 x 2 Gy) to the hemithorax + CYVADIC (cyclophosphamide 500 mg/m2 d 1, vincristine 1 mg/m2 d 1 and 5, adriamycin 40 mg/m2 d 1 and dacarbazine 200 mg/m2 d 1 and 5, several cycles before and after irradiation); II, 55 Gy (25 x 2.2 Gy) to the hemithorax + 15 Gy (6 x 2.5 Gy) to the tumor + CYVADIC (2 cycles before, 1 cycle during, and 2 cycles after irradiation); III, Mitoxantrone (14 mg/m2 q 28 d, < or = 6 cycles) followed by 70 Gy (56 x 1.25 Gy, twice a day); IV, 4-Epirubicin (110-130 mg/m2 q 28 d, < or = 6 cycles) followed by 35 Gy (28 x 1.25 Gy twice a day) to the hemithorax + 36 Gy (9 x 4 Gy every 2 days) to the tumor; V, Etoposide (150 mg/m2 1, 3, 5 q 28 d) followed by 38.5 Gy (11 x 3.5 Gy) to the hemithorax. A new system for evaluating tumor response in pleural mesothelioma was applied. None of the combined treatment programs prevented local invasive growth or the spread of mesothelioma outside the hemithorax. The median survival time was slightly increased from 8 to 12 months for those patients who completed the protocol treatments, but progressive disease was the invariable outcome. Radiation pneumonitis and fibrosis were severe and compatible with results of total loss of lung function on the irradiated side. We conclude that data relating to therapeutic responses and treatment programs in malignant mesothelioma should be better correlated internationally, if the problems associated with the evaluation of treatment and the management of patients with mesothelioma are to be improved.

Different imaging methods in the assessment of radiation-induced lung injury following hemithorax irradiation for pleural mesothelioma.

We have characterized the radiation-induced lung injury on serial chest X-rays, CTs and ultralow field MRs and evaluated the clinical value and cost/benefit ratio of the different imaging methods in 30 patients receiving high-dose hemithorax irradiation for pleural mesothelioma. Lung injury was severe in all patients, but non-specific and essentially as described in text-books. CT provided no clinically relevant, cost effective diagnostic advantage over conventional X-rays in the detection of early or late radiation-induced lung injury, but it was necessary for the evaluation of the disease status of mesothelioma. The possible advantage of MR over CT could not be evaluated and needs further studies. Optimal time-points for imaging CTs or MRs to detect early radiation-induced lung injury following high dose hemithorax irradiation were during the latter part of treatment or very shortly after the end of irradiation. Late injury or irreversible fibrosis developed rapidly after 6 months and was clearly documented by chest X-rays. We recommend serial chest X-rays at 1-2, 6 and 12 months following radiotherapy as a cost-effective method for the detection of radiation-induced lung injury with additional CTs to document the stage of mesothelioma, when needed.

N-acetylcysteine in combination with radiotherapy in the treatment of non-small cell lung cancer: a feasibility study.

N-Acetylcysteine (NAC) is a free radical scavenger and could therefore act as a radioprotector. To test the feasibility of administering NAC in combination with radiotherapy, we studied 10 patients with inoperable non-small cell lung cancer who were receiving hyperfractionated radiotherapy (RT) of 1.25 Gy B.I.D. (6-h interval) up to a total dose of 60 Gy/48 fractions/32 days. They were given NAC concomitantly with RT: 100 mg/kg i.v. 30 min before the first RT session followed by 30 mg/kg as an i.v. infusion over 7 h; and 600 mg inhaled 30 min before and after each RT session. The patients were assessed by serial CT scans and lung function studies during a 1-year follow-up period. The treatment regime was feasible, but expensive in time and resources. Normal tissue reactions and tumour responses were similar to those in a control group.

High-resolution CT in long-term follow-up after lung transplantation.

OBJECTIVE: Our aim was to evaluate the development of changes on high-resolution CT (HRCT) associated with chronic pulmonary rejection. MATERIALS AND METHODS: Repeated HRCT examinations were performed 140 times on 13 consecutive lung transplant recipients during a mean observation period of 26 months. The postoperative time interval to the first detection of each chronic change on CT was calculated and compared with the onset of chronic rejection. Bronchiolitis obliterans syndrome (BOS) or the histologic diagnosis of obliterative bronchiolitis was assessed by the published criteria of the International Society for Heart and Lung Transplantation. RESULTS: BOS developed in eight patients, on an average, within 11.6 (+/-5.0) months. Histologic diagnosis was available from five patients. On HRCT, among the first identifiable chronic changes were volume contraction, decreased peripheral vascular and bronchial markings, and thickening of septal lines, all of which appeared between 7 (+/-5.0) and 11 (+/-6.8) months postoperatively. The mean interval for appearance of bronchodilatation was 12.5 (+/-8.7) months. Hyperlucency and mosaic phenomenon were identified, on an average, 16 (+/-6.3) and 21 (+/-7.3) months after transplantation. CONCLUSION: On radiologic monitoring of lung recipients with HRCT, in addition to bronchodilatation. a special attention should be paid to the early chronic changes, including diminution of peripheral bronchovascular markings, thickening of septal lines, and volume reduction, which usually precede the establishment of the diagnosis of chronic rejection, whereas hyperlucency and mosaic phenomenon usually appear during more advanced BOS.

Evaluation of the clinical TNM staging system for malignant pleural mesothelioma: an assessment in 88 patients.

There is no universally-recognised method for staging malignant mesothelioma, although the use of computed tomograph (CT) scanning has improved the staging of non-invasive disease. The International Union against Cancer has recently proposed using the Tumour Node Metastases (TNM) staging system for mesothelioma, but in clinical practice it is difficult to assess tumour and nodal involvement due to the unique plate-like growth pattern of this tumour. In order to evaluate TNM staging we analysed pre-operative CT scans from 88 patients with histologically-confirmed malignant pleural mesothelioma, all from the same institution. The median age of the patients was 56 years (range 38-79). There were 70 men and 18 women, and 33 had tumours with epithelial histology. The median survival time was 10 months (range 0.2-110), from the date of histological confirmation of mesothelioma. The same radiologist analysed all the CT scans according to the TNM staging system. Actuarial survival curves were constructed by the Kaplan-Meier method. Survival curves for the different TNM categories were compared using the log-rank test. Node evaluation could not be completed in eight cases because the tumour had encompassed the hilum and mediastinum. In multivariate analysis, significant differences in prognosis correlated with the different T categories (P < 0.01), and the different TNM stages (P < 0.05), but not the N categories or the M categories. Larger studies are needed to assess the importance of TNM staging in the selection of treatment and as a prognostic factor for malignant mesothelioma.

The clinical importance of magnetic resonance imaging versus computed tomography in malignant pleural mesothelioma.

There is no standard therapy for malignant pleural mesothelioma (MPM), but recent reports have shown that extensive surgery combined with chemo- and radiotherapy prolongs the survival of selected patients with early stage disease. This emphasises the need for accurate staging procedures at diagnosis and reliable imaging methods to assess response to treatment. Computed tomography (CT) of the chest has been the standard imaging method for these purposes for the last decade, but it is limited in its ability to demonstrate accurately the platelike growth pattern of MPM within the thorax due to the partial volume effect on curved surfaces. In order to define the value of magnetic resonance imaging (MRI) in the imaging of MPM, we have compared the findings from 26 parallel paired CT and MRI scans of mesothelioma patients at various stages of the disease. MRI showed tumour spread into the interlobar fissures, tumour invasion of the diaphragm and through the diaphragm, and invasion of bony structures better than CT. Invasion of the chest wall and mediastinal soft tissue and tumour growth into the lung parenchyma were equally well seen on both imaging methods. CT was better for detecting the inactive pleural calcifications. MRI is a sensitive detector of the characteristic growth pattern and extension of MPM and we recommend its use more widely for the clinical management of MPM especially when evaluating tumour resectability and in research protocols when an accurate evaluation of disease extent is essential.

Contrast absorption and pancreatic inflammation following experimental ERCP.

The effect of saline and contrast agents intraductally injected into the pancreatic duct in sufficient volume to cause acinarization was studied in normal rats and in rats with acute pancreatitis. The effect of pancreatic inflammation on the disappearance of injected contrast material was investigated by injecting meglumine diatrizoate and 125I into the pancreatic duct. The activity appeared quickly in the venous blood of normal rats (peak activity at 5 minutes after injection). In rats with sodium taurocholate-induced pancreatitis, the appearance of activity in the blood was retarded. Ninety-two percent of the rats demonstrated pancreatic atrophy or pancreatitis histologically four days following acinarization of intraductally injected saline or metrizamide, meglumine diatrizoate, or meglumine sodium diatrizoate.

The diagnostic potential of contrast enhancement pharmacokinetics.

Diastizoate concentrations in the blood and twelve tissues and organs of 20 rats were measured at 40 seconds, and 2, 5, 15 and 60 minutes after bolus intravenous administration of 125 I-labeled diatrizoate and 131 I-labeled albumin. Contrast enhancement (HU) and distribution volumes(%) were calculated from this data, and the results are presented graphically. The tissues can be separated into two groups according to the rapidity of extravascular contrast medium uptake. The liver appeared to concentrate the contrast medium. Curves of local contrast enhancement with time could be constructed by a CT scanner from the data of several consecutive scans and are of potential importance in the differential diagnosis of lesions detected on CT. Repeat postcontrast CT scans could be used to detect and characterize lesions which raise a diagnostic problem. The potential diagnostic advantages of calculating percent distribution volumes from CT scans are demonstrated and discussed.

Contrast enhancement pharmacokinetics of six ionic and nonionic contrast media.

The contrast enhancement of six contrast media (CM) was compared in 13 tissues of the rat after rapid intravenous bolus injection. The rats were sacrificed at 0 and 40 seconds and 2, 5, and 15 minutes after contrast injection. 125I labeled diatrizoate, metrizamide, ioxaglate, iohexol, iopamidol, and a nonionic dimer, iodecol, were each injected at a dose of 612 mg iodine per kg body weight, and iodine concentration (IC) and contrast enhancement were calculated from radioactivity measurements. Higher blood IC values were obtained with the nonionic CM; similar enhancement patterns were seen in the spleen, heart, lungs, and brain. Renal IC was directly related to the number of iodine atoms per ion or molecule of CM. In consequence, renal IC was inversely related to the CM osmolality, but no such correlation was seen with the blood IC. Metrizamide produced the greatest IC in the organs of the gastrointestinal tract. There was no apparent correlation of IC with molecular structure of physicochemical parameters of the CM in any of the other tissues studied.

Does dilution of contrast media affect contrast enhancement? An experimental study in rats.

The effect of contrast media (CM) dilution on contrast enhancement was studied using CM representing four structurally different molecular types at osmolalities ranging from 135 to 1340 mosm/kg. Diatrizoate (ionic monomer), iopamidol (nonionic monomer), ioxaglate (ionic dimer), and iodecol (nonionic dimer) were each given at a dose of 500 mgI/kg and at concentrations of both 300 and 150 mgI/mL. Contrast media concentrations were measured using iodine 125I. Tissue blood volumes were determined using human serum albumin labeled with 131I. For each of the four CM at each of the two concentrations and after each of five time intervals following injection (0, 15, 40, 120, and 300 seconds), five rats were killed (total = 200 rats). Blood and 14 other tissues were studied. Dilution of the CM did not lead to any lower iodine tissue concentrations, iodine distribution volumes, plasma volumes, or hematocrit. The authors conclude that lowering CM osmolality by dilution with water should improve tolerance without affecting CT contrast enhancement.

Contrast media-induced renal morphologic lesions during experimental hemorrhagic necrotizing pancreatitis.

RATIONALE AND OBJECTIVES: Contrast media-induced renal morphologic changes were studied in rats. Hemorrhagic pancreatitis was induced as a means of sensitizing the animals to the effects of contrast media. METHODS: The histologically verified hemorrhagic pancreatitis was induced in Wistar rats (n = 66) by injecting 6% sodium taurocholate into the pancreatic duct. After 2 hours, the animals received intravenously 1.0 or 3.0 g iodine/kg of high-osmolal osmolal diatrizoate, low-osmolal iopromide or iohexol, iso-osmolal iotrolan or 0.2 or 0.6 g/kg of high-osmolal magnetic resonance contrast agent, gadolinium-DTPA (Gd-DTPA). Control animals received physiologic saline. The kidneys were fixed by perfusion 2 hours later, and the morphologic changes were reviewed by two independent observers blinded to the injected agent. RESULTS: The smaller dose of iohexol and the larger dose of all the contrast media induced a statistically significant (P < .001 or .01) cytoplasmic vacuolization in the proximal convoluted tubule (PCT) cells. The nonionic, low- and iso-osmolal contrast media caused as much or even significantly more vacuolization than diatrizoate. CONCLUSIONS: Hemorrhagic pancreatitis potentiates the contrast media-induced renal morphologic changes, which depend on the type and dose of the injected contrast media.

Comparative pharmacokinetics of gadolinium DTPA and gadolinium chloride.

An intravenous injection of 153Gd-labeled gadolinium-DTPA or gadolinium chloride was given to 60 rats, which were killed either 15, 40, 120, 300, 900, or 3600 seconds later. Tissue concentrations of gadolinium in the blood, liver, spleen, stomach, pancreas, renal cortex, renal medulla, lungs, heart, adrenals, gluteal muscle, fat, skin, thymus, brain, thyroid, and parathyroids were measured. Five animals were killed at each time interval with gadolinium-DTPA, and at each of the latter four time intervals (15 and 40 seconds excluded) with gadolinium chloride. The pharmacokinetics of gadolinium-DTPA and chloride differ markedly in terms of tissue concentration, distribution volumes, and the time course of these parameters. Gadolinium, when injected as a chloride, evidently forms insoluble carbonate and phosphate precipitates in the blood, which are taken up by the reticuloendothelial system. The distribution of gadolinium-DTPA on dynamic MRI should closely parallel the distribution of iodinated contrast media on dynamic computed tomography.