Short T1 Inversion Recovery Images Research Articles

Application of Short T1 Inversion Recovery Sequence in Increased Signal Intensity Following Cervical Spondylotic Myelopathy

To compare magnetic resonance (MR) short T1 inversion recovery (STIR) sequence with MR T2-weighted (T2W) sequence for detecting increased signal intensity (ISI) and assessing outcomes of ISI in cervical spondylotic myelopathy (CSM). Data of patients with CSM who showed ISI on MR imaging and had undergone cervical spine surgery were retrospectively reviewed. STIR and T2W images were examined to assess signal intensity ratio (SIR), length and grading of the ISI, maximal spinal cord compression (MSCC), canal narrowing ratio (CNR), and ligamentum flavum hypertrophy (LFH). The patients were divided into good and poor groups based on their outcomes. Chi-square tests and variance analysis were used to assess intergroup differences. Univariate and multivariate logistic regression analyses were performed to identify risk factors for poor outcomes, and receiver operating characteristic curves were plotted to detect prognostic effects. SIR and ISI lengths were significantly different between the STIR and T2 images. In the univariate logistic regression analysis, age, diabetes, SIRT2, SIRSTIR, and ISISTIR grading were significant factors. Accordingly, in the multivariate logistic regression analysis, age, diabetes, SIRT2, and SIRSTIR were included in the model. Among patients with diabetes, we observed a significant difference between SIRT2 and SIRSTIR. The STIR sequence demonstrated superior capability to the T2W sequence in detecting ISI; however, there was no obvious difference in predicted outcomes. STIR sequence has a better prognostic value than T2W sequence in patients with diabetes who have CSM. ISI grading based on the STIR sequence may be a clinically valuable indicator.

Abbreviated Breast MRI: Our Two-Year Initial Experience.

The aim of this study was to retrospectively evaluate and present our two-year experience with abbreviated breast MRI at our academic institution as a screening tool to identify primary breast cancers. Employing eight specialty trained breast radiologists, studies were interpreted using the BI-RADS MRI lexicon in this IRB-approved retrospective study. The protocol utilized T1-weighted, fat-saturated, pre- and post-contrast, short T1 inversion recovery images, and was completed within 10 minutes. Abbreviated breast MRI was offered to asymptomatic women of all breast densities, whose ages ranged from 24 to 90 years. Statistical analysis was performed for comparative data utilizing estimated odds ratios. Of 1338 patients that met inclusion criteria, 83% (1111/1338) were BI-RADS 1 or 2, 9.0% (121/1338) were BI-RADS 3, and 8% (106/1338) were categorized as either BI-RADS 4 or 5 with recommended biopsy. Biopsy of BI-RADS 4 and 5 categorized patients yielded 15 cancers for a positive predictive value (PPV) 2 of 14.2% and a PPV3 of 18.5%, with 76% (81/106) of patients undergoing the recommended biopsy. An additional cancer was detected in a BI-RADS 3 finding. All cancers detected were in women with heterogeneously dense or extremely dense breasts. Therefore, 16 cancers were detected, yielding a cancer detection rate of 12.0 per 1000. Over the next 12 to 24 months, no interval cancers were detected. Abbreviated breast MRI demonstrates a higher cancer detection rate compared with mammography only and may provide a supplemental screening method to detect breast cancers in patients with varying risk factors.

Magnetic resonance imaging of diffusion characteristics following collagenase clostridium histolyticum injection in Dupuytren's contracture.

PurposeWe aimed to evaluate the extent of collagenase clostridium histolyticum (CCH) diffusion in Dupuytren's contracture (DC) for tissues outside of the contracture cord using Magnetic Resonance Imaging (MRI) immediately after CCH injection. Methods: 10 male patients aged 57-79 with DC of the metacarpophalangeal (MCP) joints were examined. Extension deficits were 10-60°(mean, 34.3) and 0-60°(mean, 26.6) in the MCP and proximal interphalangeal (PIP) joints, respectively. CCH injection was performed according to the standard method. MRI was performed within 15min of CCH injection. Results: In all 10 cases, the extended area of high-intensity signal change outside of the cord was observed on short-T1 inversion recovery images (STIRs). Continuity from the insertion site was observed in the area of signal change involving the flexor tendon and neurovascular bundle. The signal change area spanned distally and proximally beyond the injection level. The signal change area expanded along the tendon sheath but no signal changes were observed inside the flexor tendon, suggesting the tendon sheath serves as a protective barrier from the CCH solution. After 1week of injection, the mean decrease in contracture was 32.5°(94.7%) for the MCP joint and 19.8°(74.4%) for the PIP joint. In nine out of 10 cases, the extension deficit was within five degrees of full extension in the affected finger. There was no neurovascular injury or tendon rupture at 3months of observation. Conclusions: MRI indicated the possible leakage of the drug outside of the cord during the early phase after administration, suggesting that CCH could persistently affect healthy tissues until CCH inactivates its enzyme process.

Increased Apparent Diffusion Coefficient Values of Masticatory Muscles on Diffusion-Weighted Magnetic Resonance Imaging in Patients With Temporomandibular Joint Disorder and Unilateral Pain

Myalgia of the masticatory muscles is difficult to evaluate quantitatively. The purpose of the present study was to quantitatively assess myalgia of the masticatory muscles in patients with temporomandibular disorders (TMDs) using the apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging (MRI). Patients who had undergone MRI with clinically diagnosed TMDs according to the criteria of the American Academy of Orofacial Pain and unilateral temporomandibular joint pain from March 2015 to January 2017 were prospectively enrolled. The MRI techniques used included axial diffusion-weighted imaging (DWI) and short T1 inversion recovery imaging through the neck to the skull base. The regions of interest were drawn to completely include the right and left lateral pterygoid muscles, medial pterygoid muscles, and masseter muscles on a slice demonstrating the largest area of each muscle on the ADC map. We compared each masticatory muscle of the pain side with those of the contralateral side without pain. A total of 106 patients with TMD had met the inclusion criteria (18 males, 88 females; mean age, 48.7years; range, 16 to 80). The mean ADC values of the masticatory muscles of the pain side were significantly greater than those of the no-pain sides (P<.01), as were those for the lateral pterygoid muscles (1.35±0.79×10-3mm2/second vs 1.13±0.77×10-3mm2/second), medial pterygoid muscles (1.28±0.46×10-3mm2/second vs 1.05±0.69×10-3mm2/second), masseter muscles (1.33±0.78×10-3mm2/second vs 1.09±0.64×10-3mm2/second). The ADC values of the masticatory muscles on the pain side were significantly greater than those of the contralateral side without pain. Our results suggest that DWI could be used to assess myalgia of the masticatory muscles quantitatively.

Optimal surgical margin for infiltrative soft tissue sarcomas: Assessing the efficacy of excising beyond the infiltration.

Tumor infiltration in soft tissue sarcoma (STS) is known to correlate with an inadequate surgical margin and poor local control. This study aims to determine whether the radiological infiltration (R-inf) in STS cor relates with histological infiltration (H-inf) and to devise methods to determine a resection margin for infiltrative STS. We reviewed the medical records of 145 patients with high-grade STS. We measured the R-inf on short-T1 inversion recovery or gadolinium-enhanced fat-suppressed (GdFS) magnetic resonance imaging. In addition, we assessed H-inf as the infiltrative growth of atypical tumor cells. The local control rate (LCR) was assessed using the Kaplan-Meier method. A statistically significant positive correlation was found between H-inf and R-inf (P < 0.0001). The R-inf obtained from the GdFS images exhibited a stronger correlation with H-inf than that obtained from the short-T1 inversion recovery images. Univariate and multivariate analyses revealed that a positive H-inf significantly correlated with a poor LCR. Moreover, the contaminated margins, which included intrainfiltration margins, significantly correlated with a poor LCR compared with the wide margins. R-inf as assessed by the GdFS images significantly correlates with H-inf, suggesting that we should exercise the infiltrative STS beyond their R-infs detected by the GdFS images.

Paraspinal muscle involvement in herpes zoster-induced abdominal wall pseudohernia revealed by electrophysiological and radiological studies

Segmental zoster paresis is an uncommon complication of herpes zoster, and abdominal wall pseudohernia is rare. Previous reports have emphasized the involvement of anterior rami of spinal nerves, while the involvement of posterior rami has been less frequently reported. We aimed to elucidate the involvement of posterior rami of spinal nerves in abdominal wall pseudohernia. Four patients with a diagnosis of abdominal wall pseudohernia underwent needle electromyography (nEMG) and magnetic resonance imaging (MRI). In three patients, nEMG of affected paraspinal muscles showed denervation potentials, and MRI showed hyperintensity of these muscles on short T1 inversion recovery imaging. These results suggested involvement of paraspinal muscles, and indicated that posterior rami of spinal nerves are also often affected in abdominal wall pseudohernia. MRI as well as nEMG could be useful for evaluating paraspinal muscle involvement and for the diagnosis.

Basic principles of magnetic resonance imaging for beginner oral and maxillofacial radiologists

The basic principles and diagnostic methods of magnetic resonance imaging (MRI) for beginning surgeons are described in this review. MRI is an important technique that is essential for diagnoses in the maxillofacial area. It is a scanning method that obtains tomographic images of the human body using a magnetic field. In contrast to computed tomography, it does not utilize X-rays and, therefore, represents a noninvasive test that lacks radiation exposure. It is particularly effective for soft-tissue diagnoses. MRI involves imaging protons in vivo. Protons emit a signal when a radio frequency pulse is applied in a magnetic field; the MRI device then forms an image from these signals. The basic images produced are T1- and T2-weighted images; comparison of these images is the first step of MRI-based diagnosis. Short-T1 inversion recovery images, which eliminate the signal from fat, are also useful for diagnosis. Gadolinium is used as a contrast agent for MRI. Taking sequential images at fixed intervals while injecting the contrast agent and then graphing the contrast effect along the time axis produces a time–signal intensity curve, which is useful for identifying features such as malignant neoplasms based on the graph pattern.

The Correlation between Intraoperative Microelectrode Recording and 3-Tesla MRI in Patients Undergoing ANT-DBS for Refractory Epilepsy

Background: Deep brain stimulation (DBS) of the anterior nucleus of the thalamus) (ANT) has been suggested as a treatment option in refractory epilepsy. The targeting of ANT is especially challenging due to its poor visualization in commonly used MRI sequences, lack of easily observable symptom relief during surgery and high degree of anatomical variation between individuals. Objectives: To study whether intraoperative microelectrode recording (MER), a method widely used in movement disorder surgery, provides clinically relevant information during the ANT-DBS implantation procedure. Methods: A total of 186 MER samples from 5 patients and 10 thalami obtained from ANT-DBS surgery for refractory epilepsy were analyzed with respect to the signal characteristics and location in 3-tesla (3T) MRI STIR (short T1 inversion recovery) images. The location of each MER sample was calculated relative to visible borders of the ANT after correction of the sample locations according to the position of the final DBS electrode in postoperative CT-MRI fusion images. Results: We found that the lateral aspect of the ANT lacked spiking activity consistent with the presence of white matter. The spike frequency in samples correlating with location at the ANT showed significantly lower spike frequency compared to samples correlating with location at the ventral anterior nucleus (median 3.0 and 7.0 spikes/2 s; p < 0.05), but spike bursts were morphologically similar in appearance. Trajectories entering the dorsomedial nucleus according to 3T MRI STIR images showed a yet different firing pattern with more low-amplitude regular activity. Conclusions: Our data suggest that MER provides clinically relevant information during implantation surgery by demonstrating both nucleus-specific neuronal firing patterns and white matter laminae between different nuclear groups.

Sialolithiasis in two areas of the upper lip

Minor salivary gland sialolithiasis occurs in ~1 % of all sialolithiasis cases. We report a case of sialolithiasis considered to have occurred in the minor salivary gland in two areas of the upper lip, with special emphasis on the findings from image examinations. A 33-year-old male complained of a painless mass on the left upper lip. At the first examination, there was a nodular, hard swelling that involved the left cuspid area of the upper lip. Although a panoramic radiograph revealed no abnormality, an intraoral radiograph showed a small radiopaque body with a laminar pattern. Computed tomography images indicated that a calcified body was present in two areas of the upper lip. On magnetic resonance imaging, the lesion was observed as a lower-signal area than the surrounding soft tissue. The mass had a high signal in the central area in the T2 and short T1 inversion recovery images. The sonogram showed a hypoechoic mass with an echogenic structure in the central area. An excisional biopsy of the left upper lip was performed under local anesthesia. A well-demarcated mass with a calcified body was enucleated. The histopathologic diagnosis was sialoadenitis with sialolithiasis. Most cases of minor salivary gland sialolithiasis are solitary, with multiple sialolithiasis being extremely rare. Sonograms are useful in the diagnosis of minor salivary gland sialolithiasis. Careful imaging examination is necessary to identify multiple lesions and select appropriate treatments.

Transient osteoporosis of the hip, complete resolution after treatment with alendronate as observed by MRI description of eight cases and review of the literature

Transient osteoporosis of the hip (TOH), also referred to as transient bone marrow edema syndrome, is most common in middle-aged men and often after trivial trauma or sport-related injuries. Diagnosis is usually made by eliminating other possible causes of hip pain. Magnetic resonance imaging (MRI) plays an important role in diagnosis and demonstrates a typical pattern of bone marrow edema (BME) in the form of diffuse low signal on T1-weighted images and high signal on T2 fat-suppressed or short T1 inversion recovery images. No consensus exists about the management of TOH, as it may progress to avascular necrosis. We describe eight cases of TOH treated with alendronate resulting in improvement of pain and function and complete resolution of BME on MRI. The literature is reviewed regarding TOH and the relationship with bone marrow edema syndrome, avascular necrosis of the hip, and regional migratory osteoporosis. To our knowledge, this is the first report describing the improvement of this condition after of alendronate with documented radiological improvement on follow-up MRI.

Parapharyngeal ectopic thyroid mimicking deep lobe parotid tumour along with multinodular thyroid goitre—a very rare presentation

Parapharyngeal ectopic thyroid tissue is a rare entity.1 The presence of such tissue in close approximation to other head and neck structures can pose a diagnostic dilemma as we found in our case. A 74-year-old lady presented with a 1 year history of painless gradually increasing mass in the right parotid gland region. 5 years previously she had been diagnosed with multinodular thyroid goitre. The MRI scan of the right parotid gland revealed a 4 × 3.8 × 2.5 cm mass situated predominantly within the deep lobe. This showed low-signal intensity on T1 weighted and high-signal intensity on T2 weighted and short T1 inversion recovery images (Figures 1, ​,22 and ​and3).3). These features were consistent with a radiological diagnosis of pleomorphic adenoma arising from the deep lobe of the right parotid gland and hence no fine needle aspiration was undertaken. A thyroid goitre was also noted on the scan, which coincided with her history. A total parotidectomy procedure was planned. During the surgery, the deep lobe was found to be of normal appearance and texture; therefore only superficial parotidectomy was carried out with the deep lobe left in situ. The MRI scan was repeated following surgery. The mass remained difficult to separate from the residual deep lobe of the parotid gland (Figures 4 and ​and5).5). The differential diagnosis was modified to include neurogenic tumours and paragangliomas in the parapharyngeal location based on the surgical findings. Formal excision of the parapharyngeal mass was undertaken through a transcervical approach. The mass was found to be soft, well encapsulated and lobulated lying lateral to the internal jugular vein and behind the deep lobe of the parotid gland. Surgery was uneventful. Histopathology revealed colloid filled follicles of varying sizes compatible with thyroid parenchyma. A diagnosis of ectopic thyroid was made. No papillary features were seen. Post-operatively, routine thyroid function tests were carried out and all were found to be within normal range. Imaging plays an important role in differentiating deep lobe parotid tumours from other parapharyngeal masses.2 The demonstration of a fat plane between the deep lobe of the parotid gland and the tumour is indicative of tumour originating de novo in the parapharyngeal space. Figure 1 T1 axial MRI image showing low signal mass within the deep lobe of right parotid gland. (a) Right parotid gland; (b) mass appears to be within the deep lobe; (c) left parotid gland Figure 2 T2 axial MRI image showing high signal mass within the deep lobe of right parotid gland Figure 3 Coronal short T1 inversion recovery MRI image showing the thyroid goitre along with the parotid mass. (a) Mass within the deep lobe; (b) multinodular thyroid goitre Figure 4 T1 axial MRI image following superficial parotidectomy revealing the mass to be still within the deep lobe of right parotid gland. (a) Residual parotid gland after superficial parotidectomy; (b) mass difficult to separate from parotid gland Figure 5 T2 axial MRI image following superficial parotidectomy revealing the mass to be still within the deep lobe of right parotid gland Sometimes, a mass can be so large as to compress and efface the fat planes. This makes it very difficult to distinguish between a deep lobe tumour and a parapharyngeal mass. It is important to consider parapharyngeal tumour or masses in the differential diagnosis of deep lobe parotid tumours and include ectopic thyroid as one of the parapharyngeal masses.

A New approach towards improved visualization of myocardial edema using T2‐weighted imaging: A cardiovascular magnetic resonance (CMR) study

To compare T2-weighted cardiovascular magnetic resonance (CMR) imaging with AASPIR (asymmetric adiabatic spectral inversion recovery) and STIR (short T1 inversion recovery) for myocardial signal intensity, image quality, and fat suppression. Forty consecutive patients (47 ± 16 years old) referred by cardiologists for CMR-based myocardial tissue characterization were scanned with both STIR and AASPIR T2-weighted imaging approaches. Signal intensity of left ventricular myocardium was normalized to a region of interest generating a signal-to-noise ratio (SNR). In six patients with regional edema on STIR the contrast-to-noise ratio (CNR) was assessed. Two independent observers used a scoring system to evaluate image quality and artifact suppression. Six healthy volunteers (three males, 32 ± 7 years) were recruited to compare fat suppression between AASPIR and STIR. SNR of AASPIR was greater than STIR for basal (128 ± 44 vs. 83 ± 40, P < 0.001), mid- (144 ± 65 vs. 96 ± 39, P < 0.01), and apical (145 ± 59 vs. 105 ± 35, P < 0.05) myocardium. Improved image quality and greater suppression of artifacts was demonstrated with AASPIR. In patients with regional edema, CNR increased by 49% with AASPIR, while SNR of pericardial fat did not differ (44 ± 39 vs. 33 ± 30, P > 0.05). Our findings support the implementation of an AASPIR-based approach for T2-weighted imaging due to improved pericardial fat suppression, image quality, and artifact suppression with greater CNR and SNR.

Hibernoma: MRI features in eight consecutive cases

To describe the preoperative magnetic resonance imaging findings of eight histologically-proven cases of hibernoma. The site, size, and signal characteristics of eight consecutive hibernomas were retrospectively assessed on T1-weighted spin-echo and short T1 inversion recovery (STIR)/fat-saturated T2-weighted fast spin echo magnetic resonance images. Four patients also had gadolinium-enhanced fat-saturated T1-weighted spin echo imaging. Patient age and sex, and duration of symptoms were recorded. Three female and five male patients with an average age 36 years (range 16-53 years) were included. Seven lesions occurred in the thigh, four in the anterior compartment and three in the posterior compartment. One lesion occurred superficial to the scapula. All cases demonstrated common magnetic resonance imaging findings of a well-defined, heterogeneous mass, slightly or clearly hypo-intense to subcutaneous fat on T1-weighted spin-echo images, with prominent thin low signal bands throughout the tumour. The lesions failed to fully suppress on STIR or fat-saturated T2-weighted images. Only one of the four contrast-enhanced studies demonstrated increased vascularity in the tumour. The MRI findings of a lesion that is diffusely slightly hypointense to surrounding subcutaneous fat, should prompt the operator to consider hibernoma in the differential diagnosis.

Magic Angle Imaging of the Achilles Tendon in Patients with Chronic Tendonopathy

AIMS: To assess the Achilles tendon in patients with chronic tendonopathy using magnetic resonance (MR) magic angle imaging, and to compare the appearances and uptake of contrast medium in abnormal tendons with those in normal tendons. MATERIAL AND METHODS: Eight patients with chronic Achilles tendonopathy and five normal controls were examined with the long axis of the tendon placed at 55° and at 0° to the main magnetic field. Conventional two-dimensional (2D) multi-slice images were obtained and T1 values were calculated before, and for up to 1 h after the administration of intravenous gadodiamide. Both the unenhanced appearance and the pattern of enhancement in the tendon were compared. RESULTS: In the patients with tendonopathy, high signal intensity areas were evident on the short T1 inversion recovery (STIR) images obtained at 55° in all tendons. Contrast medium enhancement was seen in six tendons and was most obvious on the images obtained at the magic angle. This was initially focal and then spread more diffusely within the tendon. After contrast medium administration, T1 values were significantly reduced in the tendonopathy group compared with normal controls ( p<0.01). On the late post-contrast medium images obtained at 55°, enhancement was evident in most of the tendon and correlated well with high signal intensity seen on STIR images. CONCLUSION: The use of magic angle MR imaging improved the demonstration of signal changes in the Achilles tendon in chronic tendonopathy. The STIR images obtained at the magic angle showed more obvious signal change than those obtained at 0°. The changes due to enhancement were much more evident on images obtained at 55° than at 0°. The uptake of contrast medium was greater in the patients than in normal controls.

MRI of the shoulder.

Shoulder imaging is one of the major applications in musculoskeletal MRI. In order to analyze the images it is important to keep informed about anatomical and pathological findings and publications. In this article MRI technique, anatomy and pathology is reviewed. Technical considerations about MR sequences and examination strategy are only shortly discussed with emphasis on turbo spin echo and short T1 inversion recovery imaging. Basic anatomy as well as recent findings, including macroscopic aspects of the supraspinatus fat pad, composition of the supraspinatus muscle belly, and variability of the glenohumeral ligaments or coracoid ligament, are presented. Basic pathological conditions are described in detail, e. g. instability particularly problems in differentiating the various subtypes of labral pathology. Rotator cuff diseases are elucidated with emphasis on some rarer entities such as subscapularis calcifying tendinitis, coracoid impingement, chronic bursitis producing the double-line sign, prominent coraco-acromial ligament and the impingement due to an inflamed os acromiale.

Frequency-Selective Fat Suppression MR Imaging

Our objectives were to further characterize an artifact related to the localized failure of the frequency-selective (FATSAT) fat suppression magnetic resonance (MR) imaging technique. We constructed two phantoms simulating human orbital anatomy and imaged them on a 1.5-T MR scanner using (FATSAT) and short T1 inversion recovery (STIR) techniques of fat suppression. The first phantom resembled orbit structural configurations; it was imaged in coronal and axial planes and in varying orientations with respect to the main magnetic field (Z axis) to study the features of the artifact and to reproduce the asymmetry seen in clinical cases. We designed the second phantom to enable quantification of the change in artifact size with change in orientation. We imaged the orbits of a normal human volunteer in similar planes and orientations, and compared the results to clinical cases demonstrating the artifact and true orbital disease. The artifact identified with localized failure of FATSAT fat suppression manifested as regions of hyperintensity maximal at fat-air interfaces, with gradual fading of the increased signal with distance from the interfaces. The artifact was most prominent when the interfaces were perpendicular to the axis of the main magnetic field (Z axis). The regions of increased brightness obscured normal orbital structures but were not associated with alterations in the geometry of these structures. Changes in orientation of the interfaces with respect to the Z axis, both in the phantoms and normal volunteer, reproduced the asymmetry of fat suppression failure seen in clinical cases. The relationship of size of the artifact to change in orientation was non-linear. The artifact was not seen on STIR images. We concluded that failure of FATSAT fat suppression may mimic orbital disease, particularly if asymmetric. As predicted by the Maxwell electromagnetism equation, slight variations in orientation of the fat-air interface to the Z axis may produce large asymmetries in fat suppression failure in the orbit. Confirmation may require either comparison with additional pulse sequences [T1-weighted spin echo (T1W SE) or STIR] or repositioning the patient's head to check for persistence of the finding with varying orientations.

Magnetic Resonance Imaging of Femoral Marrow in Patients With Myelodysplastic Syndromes or Leukemia

We evaluated magnetic resonance imaging (MRI) of femoral marrow in 85 untreated adult patients with myelodysplastic syndromes (MDS) (N = 27), aplastic anemia (N = 9), and leukemia (N = 49). Images of femoral marrow were obtained using a T1-weighted spin-echo (SE) method and a short T1 inversion recovery (STIR) technique. In patients with MDS, the change in MRI pattern from a fatty or nodular pattern to a uniform pattern correlated with disease progression. Evolution to acute leukemia in MDS patients was associated with a higher signal intensity on STIR images (lower signal intensity on T1-weighted SE images) and an extended area of involvement. The femoral marrow in patients with de novo acute myeloid leukemia (AML) showed increased signal and varied patterns (scattered to uniform) on STIR images. However, the faint pattern (grade 4a) was characteristic of M2 AML. In patients with chronic myelogenous leukemia (CML) in the chronic phase, increased leukemic mass was represented by replacement of the femoral marrow with a region of abnormal signal intensity. The extent of involved areas in these CML patients correlated with the spleen size. This study indicates that MRI of femoral marrow is an important tool for the accurate diagnosis and management of patients with MDS and leukemia that may function as an adjunct to bone marrow aspiration and biopsy.

Kernspintomographische Differenzierung osteoporotisch- und tumorbedingter Wirbelkörperfrakturen

42 patients with known malignancy and vertebral compressions underwent MRI. Sagittal T1-weighted spin-echo images pre and post Gd-DTPA, out of phase long TR gradient-echo images (GE) and short T1 inversion recovery images (STIR) were obtained at 1.0 T. The results were confirmed by histology (6/42) or clinical data (28/42) and follow up MRI studies (8/42). In 39 of 42 cases a correct differentiation between osteoporotic and tumorous vertebral compression fractures was possible by quantification and correlation of SE and GE signal intensities. Gd-DTPA did not improve differential diagnosis, since both tumour infiltration and bone marrow oedema in acute compression fracture showed comparable enhancement. STIR-sequences were most sensitive for pathology but unspecific due to a comparable amount of water in tumour tissue and bone marrow oedema. Susceptibility-induced signal reduction in GE images and morphologic criteria proved to be most reliable for differentiation of benign and tumour-related fractures. In the rare cases of single and nearly complete vertebral compressions with complete loss of bone marrow, differentiation with MRI was not possible.

Spin-Echo and STIR MR Imaging of Sports-Related Muscle Injuries at 1.5 T

Seventy patients with clinically diagnosed athletic muscle injuries of varying severity were studied with MR imaging at 1.5 T. Twenty underwent follow-up MR studies. In all cases, SE T1-weighted and double-echo T2-weighted pulse sequences were used. These were supplemented by short T1 inversion recovery (STIR) sequence in 36 cases. Muscle injuries were more readily seen with STIR images than with SE T2-weighted images. In both initial assessment and follow-up of tears, the use of the STIR technique allowed the greatest lesion/muscle contrast. Short TR, short TE SE images provided anatomic detail and were an adjunct to T2-dependent SE images in the evaluation of organized hematomas (11 cases). Follow-up MR studies in 20 patients at variable time intervals allowed demonstration of regression of the tear in 11 cases, fibrous scar formation in 5 cases, and recurrence of the tear in 4 cases. Evolution of hematomas into scar and into cyst was demonstrated in three and two cases, respectively. Owing to the additive effect of T1 and T2 mechanisms, the STIR sequence is well suited for initial evaluation and can replace T2-weighted images in the follow-up of muscle trauma.

Early and late bone-marrow changes after irradiation: MR evaluation.

Knowledge of the chronologic evolution of bone-marrow changes during and after radiation therapy is essential in differentiating normal postradiation changes from other marrow abnormalities. The appearance of the lumbar vertebral bone marrow was studied on 55 serial spin-echo and short-T1 inversion-recovery (STIR) MR images obtained in 14 patients receiving radiation therapy for Hodgkin disease, seminoma, or prostate carcinoma. Images were obtained before, at weekly intervals during, and at various monthly intervals up to 14 months after a 3- to 6-week course of fractionated paravertebral lymph-node irradiation of 1500-5000 rad (15-50 Gy). During the first 2 weeks of therapy, there was no definite change in the appearance of the marrow on spin-echo images; however, there was an increase in signal intensity on the STIR images, apparently reflecting early marrow edema and necrosis. Between weeks 3 and 6, the marrow showed an increasingly heterogenous signal and prominence of the signal from central marrow fat, shown best on T1-weighted images. Late marrow patterns (6 weeks to 14 months after therapy) varied and consisted of either homogenous fatty replacement or a band pattern of peripheral intermediate signal intensity, possibly representing hematopoietic marrow surrounding the central marrow fat. No focal marrow lesions or soft-tissue edema were identified during the course of radiation therapy; their presence should raise the possibility of the presence of a pathologic process other than radiation change. These data suggest that MR can detect radiation-induced marrow changes as early as 2 weeks after starting therapy, and that there are at least two distinct types of late marrow MR patterns.