Usefulness of cone-beam computed tomography-reformatted epidurography in percutaneous epidural adhesiolysis: A pilot study.

BACKGROUND: Conventional epidurography (CE) is thought to have insufficient usefulness on percutaneous epidural adhesiolysis (PEA). We aimed to evaluate the association between the outcome of PEA and cone-beam computed tomography-reformatted epidurography (CBCT-RE). METHODS: After ethics board approval and written informed consent were obtained, we performed 30 PEA in 26 participants, and evaluated their post-PEA image findings. Two independent radiologists categorized and recorded the occurrence of contrast in the intracanal ventral and extraforaminal regions on CE, and in the dorsal canal (DC), ventral canal (VC), dorsal foramen (DF), and ventral foramen (VF) on CBCT-RE. Reproducibility was assessed using intraclass correlation coefficients (ICCs). Baseline characteristics along with contrast distribution patterns of CE and CBCT-RE were analyzed in terms of their association with symptom relief at 1 month after PEA. RESULTS: The rate of patients with symptoms relief >50% after PEA was 63.3%. The inter-reader agreement was higher for CBCT-RE (ICC = 0.955) than for CE (ICC = 0.793). Participants with contrast coexisting in VC and DF adjacent to the irritated nerve root on CBCT-RE ( p = 0.015) had a significantly better response after PEA than those without contrast at these locations on CBCT-RE, independent of baseline characteristics (adjusted odds ratio: 11.414 [ p = 0.012]). CONCLUSION: CBCT-RE with identifying contrast distribution patterns is useful for predicting outcome of PEA.

Value of CT in targeted CT-guided epidural blood patching: Predictors for successful epidural punctures.

BACKGROUND AND PURPOSE: Differentiating epidural from intrathecal punctures before computed tomography (CT)-guided epidural blood patching (EBP) is subjective, relying on operator experience. This study aimed to investigate CT findings for epidural and intrathecal punctures and identify reliable predictors for successful epidural punctures before targeted CT-guided EBP. MATERIALS AND METHODS: We included 65 patients with low-cerebrospinal fluid (CSF)-pressure headache receiving targeted CT-guided EBP between January 2021 and October 2022 in this retrospective study. We analyzed clinical data, technical information, and CT features before EBP. Fisher's exact test was used for discrete variables, while Mann-Whitney U test was used for continuous variables. Positive (PLR) and negative likelihood ratios (NLR) were calculated to identify predictors for confirming epidural punctures. RESULTS: We confirmed 43 patients as epidural punctures and 22 patients as intrathecal punctures. Before contrast injection, epidural fat at the needle tip in the epidural group was higher than the intrathecal group (37.2 % [16/43] vs. 4.5 % [1/22], p = 0.006). After contrast injection, the "contrast-needle tip connection" sign was mostly observed in the epidural group than the intrathecal group (95.3 % [41/43] vs. 9.1 % [2/22], p < 0.001). Additionally, the epidural group had significantly higher boomerang-shaped contrast morphology than the intrathecal group (65.1 % [28/43] vs. 9.1 % [2/22], p < 0.001). The "contrast-needle tip connection" sign had the highest PLR (10.49) and lowest NLR (0.05). CONCLUSION: Identifying epidural fat at the needle tip, "contrast-needle tip connection" sign, and boomerang-shaped contrast morphology on CT scans are useful for confirming proper placement of the needle tip within the epidural space.

Efficacy and reliability of three-dimensional fusion guidance for fluoroscopic navigation in transarterial embolization for refractory musculoskeletal pain.

Background: This study aimed to evaluate the efficacy and reliability of three-dimensional (3D) fusion guidance in roadmapping for fluoroscopic navigation during trans-arterial embolization for refractory musculoskeletal pain (TAE-MSK pain) in the extremities. Methods: The included research patients were divided into two groups: group A-TAE-MSK pain performed without the use of 3D fusion guidance; group B-TAE-MSK pain performed with the use of 3D fusion guidance for fluoroscopic navigation. We compared the procedure time, radiation dose, visual analogue scale for pain scores, and adverse effects (before and 3 months after TAE-MSK pain) among the two groups. In the group B, we determined the reliability of ideal branch angle for pre-operative non-contrast 3D magnetic resonance angiography (MRA) and intra-operative 3D cone beam computed tomography (CBCT) angiography. Results: We recruited 65 patients, including 23 males and 42 females (average age 58.20±12.58 years), with 38 and 27 patients in groups A and B. A total of 247 vessels were defined as target branch vessels. Significant changes were observed in the fluoroscopy time which was 32.31±12.39 and 14.33±3.06 minutes, in group A and group B (P<0.001), respectively; procedure time, which was 46.45±17.06 in group A and 24.67±9.78 in group B (P<0.001); and radiation exposure dose, determined as 0.71±0.64 and 0.34±0.29 mSv (P<0.01) in group A and group B, respectively. Furthermore, the number of target branch vessels, that underwent successful catheterization were 107 (97%) in group B as compared to 96 (70%) in group A, which was also significant (P<0.001). The study also showed that the ideal branch-angle has a similarly high consistency in pre-operative and intra-operative angiography based on the intra-class correlation coefficient (ICC) (0.994; 0.990, respectively). Conclusions: 3D fusion guidance for fluoroscopic navigation not only is a reliable process, but also effectively reduces the operation time and radiation dose of TAE-MSK pain.

The Value of 18F-FDG PET/MRI in Detecting Lumbar Radiculopathy for Selective Percutaneous Endoscopic Discectomy: a Case Report.

Magnetic resonance imaging (MRI) is the most popular imaging modality for investigating intervertebral disc herniation. However, it has a high chance for identifying incidental findings that are morphologically or structurally abnormal but not responsible for patients' symptoms. Although a previous study suggested that 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) may help identify neuroinflammation in lumbar radiculopathy, there is currently no direct evidence obtained from surgery. Here, we describe the case of a 32-year-old man with low back pain and right leg paresthesia for 7 months. MRI demonstrated disc herniation at the L3-L4, L4-L5 and L5-S1 levels, causing bilateral L5 and left S1 root compression. 18F-FDG PET/MRI demonstrated increased 18F-FDG uptake at the right L5 root, which was compatible with the patient's symptoms. Transforaminal percutaneous endoscopic lumbar discectomy (PELD) was performed. Intraoperative images revealed a swollen nerve root at the right L5 after removal of the herniated disc. After surgery, the patient experienced immediate pain relief and had no recurrence at the 6-month follow-up. When performing PELD in patients with multilevel radiculopathy identified on MRI, the use of 18F-FDG PET/MRI can help in accurate localization of the symptomatic roots and minimize surgical incision and soft-tissue injury.

Shared alterations in hippocampal structural covariance in subjective cognitive decline and migraine.

Introduction: Subjective cognitive decline (SCD) and migraine are often comorbid. Hippocampal structural abnormalities have been observed in individuals with both SCD and migraine. Given the known structural and functional heterogeneity along the long axis (anterior to posterior) of the hippocampus, we aimed to identify altered patterns of structural covariance within hippocampal subdivisions associated with SCD and migraine comorbidities. Methods: A seed-based structural covariance network analysis was applied to examine large-scale anatomical network changes of the anterior and posterior hippocampus in individuals with SCD, migraine and healthy controls. Conjunction analyses were used to identify shared network-level alterations in the hippocampal subdivisions in individuals with both SCD and migraine. Results: Altered structural covariance integrity of the anterior and posterior hippocampus was observed in the temporal, frontal, occipital, cingulate, precentral, and postcentral areas in individuals with SCD and migraine compared with healthy controls. Conjunction analysis revealed that, in both SCD and migraine, altered structural covariance integrity was shared between the anterior hippocampus and inferior temporal gyri and between the posterior hippocampus and precentral gyrus. Additionally, the structural covariance integrity of the posterior hippocampus-cerebellum axis was associated with the duration of SCD. Conclusion: This study highlighted the specific role of hippocampal subdivisions and specific structural covariance alterations within these subdivisions in the pathophysiology of SCD and migraine. These network-level changes in structural covariance may serve as potential imaging signatures for individuals who have both SCD and migraine.

The Role of Power Doppler Ultrasonography in Caudal Epidural Injection.

Background and Objectives: Although the ultrasound-guided technique is used in caudal epidural injections, severe complications can happen if ultrasound cannot identify the occurrence of intravascular injection. To determine intraepidural and intravascular injection during caudal epidural injections, we used power Doppler ultrasonography (PDU) when injecting medications into the epidural space. Materials and Methods: This is a retrospective study that enrolled a total of 277 patients with refractory low back pain or degenerative disc from January 2019 to December 2019. The injectate flow of caudal epidural injections was examined with the assistance of PDU and confirmed by fluoroscopy. Four flow patterns were identified by PDU in our study: the "Earthworm sign," the "Patch sign," the "Tubular sign" and the "Absent flow sign." The accuracy of PDU in identifying intraepidural and intravascular injections was determined by fluoroscopy images recorded during each injection. Results: We evaluated 277 patients (mean age, 68.6 ± 13.2 years; 106 men). The "Patch sign" showed a sensitivity of 88.76% and a specificity of 80% in predicting epidural injection without intravascular injection. The "Earthworm sign" demonstrated a sensitivity of 70% and a specificity of 100% in detecting intravascular injection. The "Tubular sign" showed a specificity of 100% and a sensitivity of 9.4% in predicting successful epidural injection. The absence of a flow signal showed a sensitivity of 1.87% and a specificity of 90% in predicting successful epidural injection. Conclusions: Ultrasound-guided caudal epidural injection can accurately determine intraepidural and intravascular injections with the assistance of PDU and is thus a good alternative technique to fluoroscopy-guided caudal epidural injection.

Case Report: Nerve Root Entrapment Due to Epidural Fibrosis in a Patient With Failed Back Surgery Syndrome: Value of 2-18F-Fluorodeoxyglucose Simultaneous Positron Emission Tomography-Magnetic Resonance Imaging.

Failed back surgery syndrome (FBSS) is a highly prevalent condition in patients after spine surgery. Although magnetic resonance imaging (MRI) is the gold standard for the diagnosis of epidural fibrosis, it is sometimes difficult to determine if epidural fibrosis contributes to radiculopathy. Herein, we share our experience in locating radiculopathy lesions using simultaneous positron emission tomography (PET)/MRI. 2-[18F]-FDG (18F-fluorodeoxyglucose) simultaneous PET/MRI maps of body glucose metabolism detected using PET can be used to correlate anatomical details provided by MRI to offer a very clear picture of neural inflammation due to extensive epidural fibrosis. More applications of 2-[18F]-FDG simultaneous PET/MRI in low back pain and other musculoskeletal diseases should be further investigated in the future.

Utility of magnetic resonance spectroscopy and diffusion-weighted imaging for detecting changes in the femoral head in divers with hip pain at risk for dysbaric osteonecrosis.

BACKGROUND: Ischemia before the development of dysbaric osteonecrosis (DON) in femoral heads has never been investigated. We assessed whether quantitative magnetic resonance spectroscopy (MRS) and diffusion weighted imaging (DWI) could detect dysbaric changes in divers with hip pain. METHODS: This IRB-approved exploratory study recruited 17 divers [9 with hip pain (Group 1); 8 asymptomatic (Group 2)] with normal findings on radiographs and conventional magnetic resonance imaging scans were age-, gender- and body-mass-index matched to 17 non-divers as controls (Group 1C, 2C). Apparent diffusion coefficients (ADCs) and MRS spectra were obtained from regions/voxels of interest on the femoral heads of all subjects. LCModel was used to determine water content, lipid composition, and the unsaturation index in bone marrow. Mann-Whitney non-parametric test was used to compare results of quantitative MRS and ADCs of ipsilateral femoral heads between divers and controls. RESULTS: MRS of the ipsilateral femoral heads revealed higher water (peak: 4.7 ppm) content, lower total lipid fraction (TLF), and higher unsaturation index (UI) of lipids in Group 1 than in Group 2 (water: P=0.040; UI: P=0.022) and Group 1C (water: P=0.027; TLF: P=0.039; UI: P=0.009). In contrast, femoral head ADCs were comparable between divers and controls. Five out of nine symptomatic divers were contacted for follow-up MRS and DWI studies, and the mean difference in water content in the femoral heads of patients with osteonecrosis was also higher than that in patients with symptom relief (osteonecrosis: 0.077±0.130 vs. symptom relief: 0.003±0.010). CONCLUSIONS: Dysbaric change in the femoral heads of divers with hip pain can be detected using quantitative MRS, which reveals increases in water content and UI of lipids, and a decrease in TLF.

Median Nerve Injury in Ultrasound-Guided Hydrodissection and Corticosteroid Injections for Carpal Tunnel Syndrome.

PURPOSE: Permanent nerve damage after corticosteroid injection has been suggested when symptoms of median nerve injury (MNI) are irreversible. We assess the outcomes of MNI and their association with ultrasonography (US)-guided hydrodissection and the following corticosteroid injection for symptomatic carpal tunnel syndrome (CTS). METHODS: US-guided hydrodissection and the following corticosteroid injections were administered to 126 CTS patients. Occurrence of MNI, clinical data, and post-hydrodissection findings were evaluated. Post-hydrodissection findings included vascular injury during hydrodissection, altered echogenicity, reduced flattening ratio, and increased cross-sectional area of the MN at the inlet of the carpal tunnel (MN-CSA-Inlet) on ultrasonography after hydrodissection. The relevance of MNI with respect to these clinical data and findings was determined. The outcome was rated using Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scores. RESULTS: Nine patients suffered MNI (incidence, 7.1 %) but improved significantly at follow-up. Clinical data and vascular injury during hydrodissection, altered echogenicity, and reduced flattening ratio after hydrodissection were unrelated to prolonged transient MNI (p > 0.05). MNI was significantly associated with increased CSA (p = 0.005). A CSA increase > 2 mm2 after hydrodissection yielded the greatest performance (0.979) for MNI in the receiver operating characteristic analysis. Decreases in BCTQ scores after injection did not differ significantly between groups with and without MNI (p > 0.05). CONCLUSION: MNI during hydrodissection may be reversible. MNI is indicated by an increase in MN-CSA-inlet immediately after hydrodissection.

Shared Patterns of Brain Functional Connectivity for the Comorbidity between Migraine and Insomnia.

Migraine is commonly comorbid with insomnia; both disorders are linked to functional disturbance of the default mode network (DMN). Evidence suggests that DMN could be segregated into multiple subnetworks with specific roles that underline different cognitive processes. However, the relative contributions of DMN subnetworks in the comorbidity of migraine and insomnia remain largely unknown. This study sought to identify altered functional connectivity (FC) profiles of DMN subnetworks in the comorbidity of migraine and insomnia. Direct group comparisons with healthy controls, followed by conjunction analyses, were used to identify shared FC alterations of DMN subnetworks. The shared FC changes of the DMN subnetworks in the migraine and insomnia groups were identified in the dorsomedial prefrontal and posteromedial cortex subnetworks. These shared FC changes were primarily associated with motor and somatosensory systems, and consistently found in patients with comorbid migraine and insomnia. Additionally, the magnitude of FC between the posteromedial cortex and postcentral gyrus correlated with insomnia duration in patients with comorbid migraine and insomnia. Our findings point to specific FC alterations of the DMN subnetwork in migraine and insomnia. The shared patterns of FC disturbance may be associated with the underlying mechanisms of the comorbidity of the two disorders.

Fried egg sign: A typical ultrasonography feature of neurolymphomatosis.

Neurolymphomatosis (NL) is a rare condition caused by non-Hodgkin's lymphoma or leukemia. We present a case of NL and describe ultrasound features, including the "fried egg sign" in which there is a clear demarcation between an avascular echogenic core and a hypoechoic vascularized peripheral zone that may help to distinguish NL from primary nerve sheath tumors.

Hypoperfusion of the infrapatellar fat pad and its relationship to MRI T2* relaxation time changes in a 5/6 nephrectomy model.

The purpose of present study was to longitudinally investigate the alterations in infrapatellar fat pad (IPFP) vascularity in 5/6 nephrectomized rats by using dynamic contrast enhanced (DCE) MRI and IPFP degeneration by using MRI T2* relaxation time. Twelve male Sprague-Dawley rats were assigned to a control group and a 5/6 nephrectomy CKD group. The right knees of all rats were longitudinally scanned by 4.7 T MRI, and serial changes in the IPFP were assessed at 0, 8, 16, 30, and 44 weeks by DCE-MRI (parameters A, kel and kep) and MRI T2* mapping. After MRI measurements, knee specimens were obtained and evaluated histologically. The CKD group had IPFPs with lower blood volume A and lower permeability kep values from 16 weeks (p < 0.05), lower venous washout kel value from 30 weeks (p < 0.001), and significantly higher T2* values reflecting adipocyte degeneration beginning at 16 weeks (p < 0.05). The histopathological results confirmed the MRI findings. Hypoperfusion and adipocytes degeneration related to CKD were demonstrated in a rodent 5/6 nephrectomy model. DCE parameters and MRI T2* can serve as imaging biomarkers of fat pad degeneration during CKD progression.

Diffusion tensor imaging findings of the median nerve before and after carpal tunnel corticosteroid injection in patients with carpal tunnel syndrome: a preliminary study.

BACKGROUND: Corticosteroid injections are a popular technique for carpal tunnel syndrome (CTS) treatment and are believed to provide rapid symptom relief. PURPOSE: To use magnetic resonance diffusion tensor imaging (MR-DTI) to determine the association between diffusion values of the median nerve (MN) at several anatomic locations and symptom relief in patients with CTS following corticosteroid injection. MATERIAL AND METHODS: MR-DTI was performed on 15 wrists of 12 patients with CTS before and two weeks after ultrasound-guided corticosteroid injections. We recorded the patients' clinical data including sex, age, side of injection, satisfaction, and symptom relief. Satisfaction and symptom relief were rated using a Likert scale and the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scale. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the MN at the levels of the distal radioulnar joint (DRUJ), pisiform bone, and hamate bone were determined. RESULTS: All patients had ≥50% satisfaction on the injection side. In comparison with baseline values, post-injection ADC was significantly lower ( P = 0.001) but FA was not significantly higher ( P = 0.11) at the pisiform bone level on the injected wrists. At the DRUJ and hamate bone levels, no obvious inter-scan change in FA and ADC ( P > 0.05) was observed. The decrease in ADC at the pisiform bone level strongly correlated with the decrease in BCTQ scores (r = 0.628; P = 0.012). CONCLUSION: Symptom relief in patients with CTS receiving corticosteroid injection is related to the change in ADC of the median nerve at the level of the pisiform bone, as determined using MR-DTI.

Ultrasound-Guided Corticosteroid Injection in Patients with Carpal Tunnel Syndrome: Efficacy of Intra-Epineurial Injection.

PURPOSE: To identify the ultrasound (US) findings of intra-epineurial corticosteroid injection during US-guided hydrodissection in patients with carpal tunnel syndrome (CTS), and to determine their clinical relevance in relation to treatment outcomes. MATERIALS AND METHODS: We performed 101 US-guided hydrodissections and corticosteroid injections in 101 patients with CTS, and evaluated their pre- and post-injection US findings. We categorized these injections into two groups based on the occurrence of intra-epineurial injection. We also recorded clinical data including sex, age, side of injection, BMI, and the duration of pre-injection CTS-related discomfort. The outcomes were measured using the Likert satisfaction scale and Boston Carpal Tunnel Questionnaire (BCTQ) scores. The clinical data, cross-sectional area of the median nerve (CSA-MN) at the inlet of the carpal tunnel measured on US images, and the symptom relief for the patients receiving intra-epineurial and extra-epineurial injection were compared. RESULTS: The intra-epineurial injection rate was 38.6 % in the 101 US-guided injections. The clinical data, pre-injection CSA-MN at the inlet of the carpal tunnel, and pre-injection BCTQ scores showed no significant intergroup differences (p > 0.05). The group with intra-epineurial injections had significantly decreased CSA-MN (difference in means, 2.5 mm2; p < 0.0001), greater patient satisfaction (p = 0.002), and lower BCTQ scores (p < 0.05) than the group with extra-epineurial injections. CONCLUSION: We characterized the US findings of intra-epineurial corticosteroid injection during US-guided hydrodissection. Intra-epineurial injection provided a more meaningfully reduction in edema of the MN, greater patient satisfaction, and greater symptom relief than extra-epineurial injection.

Assessment of factors that could affect the success of US-guided contrast injection for hip MR arthrography.

BACKGROUND: To retrospectively evaluate the association between possible influencing factors and failed first attempts to inject a contrast agent intra-articularly under ultrasound (US)-guidance for direct magnetic resonance (MR) arthrography of the hip joint. METHODS: Ninety consecutive patients (38 women and 52 men; mean age, 42 years) undergoing US-guided hip MR arthrography (3 bilaterally) were retrospectively included in this study. The potential influencing factors were sex, age, body mass index (BMI), side of injection, target site, trajectory of the needle, additional use of needle tip rotation, failed first-attempt, and capsule elongation at the site of needle insertion. RESULTS: First-attempt failure was significantly associated with reduced capsule elongation at the target site and no additional use of needle tip rotation (OR 10.708; 95% CI 1.847-62.059; OR 3.518; 95% CI 1.120-11.047). Capsule elongation (sufficient for needle bevel insertion) was significantly larger at the femoral head-neck junction (5.2 ± 1.5 mm) than at the femoral head (2.9 ± 1.3 mm) (p < 0.001). CONCLUSION: Less capsular elongation of the femoral head and no additional use of needle tip rotation to reduce the difficulty in contrast material delivery can increase the first-attempt failure rate in patients undergoing US-guided hip arthrography.

Knee subchondral bone perfusion and its relationship to marrow fat and trabeculation on multi-parametric MRI and micro-CT in experimental CKD.

The pathogenesis of chronic kidney disease (CKD) is multifactorial. In the progression of CKD arthropathy, arteriosclerosis may alter the knee subchondral bone marrow by altering blood flow through the bone vasculature. Herein, multi-parametric MRI assessment, including dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), magnetic resonance spectroscopy (MRS), MRI T2*, contrast enhanced MR angiography (CE-MRA), and micro-CT were applied in a rodent nephrectomy model to: 1) investigate the blood perfusion of subchondral bone marrow and its relationship to fat water content and trabeculation pattern in CKD and 2) demonstrate the feasibility of using multi-parametric MRI parameters as imaging biomarkers to evaluate the disease's progression. Two groups of rats in our study underwent either 1) no intervention or 2) 5/6 nephrectomy. We found that in the CKD group, perfusion amplitude A and elimination constant k el values were significantly decreased, and vascular permeability k ep was significantly increased. MRS showed that fat fraction (FF) was significantly lower, water fraction (WF) was significantly higher in the CKD group. Micro-CT showed a significant loss of trabecular bone. Knee subchondral bone marrow perfusion deficiency in experimental CKD may be associated with decreased fat content, increased water content, and sparse trabeculation.

Localized Langerhans cell histiocytosis masquerading as Brodie's abscess in a 2-year-old child: a case report.

Langerhans cell histiocytosis (LCH), formerly known as histiocytosis X, refers to a spectrum of diseases characterized by idiopathic proliferation of histiocytes that produce either focal (localized LCH) or systemic manifestations (Hand-Schüller-Christian disease and Letterer-Siwe disease). Localized LCH accounts for approximately 60-70 % of all LCH cases. Osseous involvement is the most common manifestation and typically involves the flat bones, along with lesions of the skull, pelvis, and ribs. Localized LCH in bone shows a wide spectrum of clinical manifestations and radiologic features that may mimic those of infections as well as benign and malignant tumors. The diagnostic imaging findings of localized LCH are also diverse and challenging. The penumbra sign is a common and characteristic magnetic resonance imaging (MRI) feature of Brodie's abscess, but is rarely seen in localized LCH. In this report, we describe a case of localized LCH misdiagnosed as Brodie's abscess in a 2-year-old child based on clinical symptoms, laboratory findings, and pre-diagnostic MRI findings (penumbra sign). Therefore, the penumbra sign is not sufficient to clearly establish the diagnosis of Brodie's abscess, and the differential diagnosis of localized LCH should be considered when a child with an osteolytic lesion presents with a penumbra sign.

Change in T2* relaxation time of Hoffa fat pad correlates with histologic change in a rat anterior cruciate ligament transection model.

The Hoffa fat pad (infrapatellar fat pad) is a source of post-traumatic anterior knee pain, and Hoffa disease is a syndrome leading to chronic inflammation of the fat pad. Herein, change in T2* relaxation time of the fat pad was measured in a rodent anterior cruciate ligament transection (ACLX) model in order to (i) examine the causal relationship of anterior cruciate ligament (ACL) deficiency and Hoffa disease and (ii) demonstrate the feasibility of using T2* as an imaging biomarker to monitor disease progression. Three groups of male Sprague Dawley rats (n = 6 each group), received either (i) no intervention; (ii) sham surgery at the right knee; or (iii) right ACLX. T2* relaxation time was measured and histology was examined in the Hoffa fat pad after surgery. At 13 and 18 weeks after surgery, T2* values were significantly higher in the right fat pad than the left (p < 0.001) and significantly higher in the ACLX group than the control and sham groups (p < 0.001). Histology showed fibrosis and degeneration of adipocytes in the right knees of the ACLX group. We conclude that ACL deficiency and Hoffa disease are causally related and that MRI T2* value can serve as an imaging biomarker of Hoffa disease progression.